DE112014001483T5 - Three-dimensional coordinate scanner and operating procedures - Google Patents

Abstract

The invention relates to a contactless optical three-dimensional measuring device, comprising: a first projector, a first camera, a second projector and a second camera; an electrically coupled to the first projector, the first camera, the second projector and the second camera processor; and a computer-readable medium that, when executed by the processor, causes the first digital signal to be detected at a first time and the second digital signal to be detected at a second time other than the first time, and three-dimensional coordinates of a first point determined on the surface based at least in part on the first digital signal and the first distance and determines three-dimensional coordinates of a second point on the surface based at least partially on the second digital signal and the second distance.

Description

Background of the invention

The subject matter disclosed herein relates to a three-dimensional coordinate scanner, and more particularly to a triangulation scanner having multiple modalities of data acquisition.

The detection of three-dimensional coordinates of an object or an environment is known. You can use different methods such as runtime or triangulation methods. Runtime systems such as a laser tracker, a total station, or a runtime scanner can direct a beam of light, such as a laser beam, at a retroreflector target or at a point on the surface of the object. An absolute distance meter is used to determine the distance to the target or point based on the amount of time the light takes to travel to the target or point and back. By moving the laser beam or the target over the surface of the object, the coordinates of the object can be determined. Runtime systems have advantages in that they have relatively high accuracy, but in some cases they may be slower than some other systems because they usually need to measure each point on the surface individually.

In contrast, a scanner that uses triangulation to measure three-dimensional coordinates projects either a light pattern in a line (eg, a laser line from a laser line probe) or an area-covering light pattern (eg, structured light) onto the surface , A camera is coupled in fixed relation to the projector, for example, by attaching a camera and the projector to a common frame. The light emitted by the projector is reflected off the surface and captured by the camera. Since the camera and the projector are arranged in a fixed relationship, the distance to the object can be determined according to the principles of trigonometry. Compared to coordinate measuring machines that use probe probes, triangulation systems offer advantages in that they quickly capture coordinate data over a wide range. The resulting detection of three-dimensional coordinate values provided by the triangulation system is referred to herein as "point cloud data" or simply as a "point cloud".

A number of problems can interfere with the acquisition of high accuracy point cloud data when using a laser scanner. These problems include, but are not limited to: variations in the light level captured across the image plane of the camera due to deviations in the reflectance of the object surface or deviations in the angle of incidence of the surface relative to the projected light; low resolution near an edge such. B. edges of holes; and, for example, a multipath fault. In some cases, the operator may not notice a problem or be unable to eliminate the problem. In these cases, missing or incorrect point cloud data is the result.

Accordingly, while existing scanners are suitable for their intended purpose, there is still a need for improvement and, more particularly, for providing a scanner that can adapt to undesirable conditions and provide improved data point detection.

Brief description of the invention

According to one aspect of the invention, a contactless optical three-dimensional measuring device is provided. The non-contact optical three-dimensional measuring apparatus comprises: an assembly including a projector, a first camera, and a second camera, wherein the projector, the first camera, and the second camera are fixed to each other with a first distance between the projector and the first camera and a second distance between the projector and the second camera, the projector having a light source, wherein the projector is configured to emit on a surface of an object a first light having any one of a plurality of spatially varying patterns, the first camera a first lens and a first photosensitive array, wherein the first camera is configured to capture a first portion of the first light reflected from the surface and responsively generate a first digital signal, the first camera having a first field of view; first field of vision a first sight is second region of the first camera, the second camera having a second lens and a second photosensitive array, wherein the second camera is configured to capture a second portion of the first light reflected from the surface and in response to generate a second digital signal the second camera has a second field of view, the second field of view being a second field of view of the second camera, the second field of view being different from the first field of view; an electrically coupled to the projector, the first camera and the second camera processor; and a computer-readable medium that, when executed by the processor, causes the first digital signal to be detected at a first time and the second digital signal to be detected at a second time other than the first time, and three-dimensional coordinates of a first point on the Determines surface based at least partially on the first digital signal and the first distance and determines three-dimensional coordinates of a second point on the surface based at least partially on the second digital signal and the second distance.

According to one aspect of the invention, a method for determining three-dimensional coordinates on a surface of an object is provided. The method comprises: providing an assembly comprising a projector, a first camera and a second camera, wherein the projector, the first camera and the second camera are fixed to each other, wherein a first distance between the projector and the first camera and a second space between the projector and the second camera, the projector having a light source, wherein the projector is configured to emit on the surface a first light having any of a plurality of spatially varying patterns, the first camera having a first lens and a first photosensitive array, wherein the first camera is configured to capture a first portion of the first light reflected from the surface, the first camera having a first field of view, the first field of view being a first viewing angle range of the first camera; Camera a second lens and a second phot The second camera is configured to capture a second portion of the first light reflected from the surface, the second camera having a second field of view, the second field of view being a second viewing angle range of the second camera, the second field of view of first field of view is different; Providing a processor electrically coupled to the projector, the first camera, and the second camera; Emitting the first light with one of the plurality of spatially varying patterns selected first pattern in a first operation from the projector to the surface; Capturing a first image of the surface with the first camera in the first process and in response sending a first digital signal to the processor; Determining a first set of three-dimensional coordinates of first points on the surface, wherein the first set is based, at least in part, on the first pattern, the first digital signal, and the first distance; Performing a diagnostic method to evaluate the quality of the first sentence; Determining a second pattern of the first light selected from the plurality of spatially varying patterns, wherein the second pattern is based, at least in part, on results of the diagnostic method; Emitting the first light with the second pattern in a second process from the projector onto the surface; Taking a second image of the surface with the second camera in the second process and in response sending a second digital signal to the processor; and determining a second set of three-dimensional coordinates of second points on the surface, the second set based at least in part on the second pattern, the second digital signal, and the second distance.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

Brief description of the drawings

The subject matter contemplated as being the invention is particularly pointed out and clearly claimed in the claims at the end of the specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings. Show it:

1 a schematic plan view of a scanner according to an embodiment of the invention;

2 : A flow chart illustrating a procedure for operating the scanner from 1 shows;

3 a schematic plan view of a scanner according to another embodiment of the invention;

4 : A flow chart illustrating a procedure for operating the scanner from 3 shows;

5A a schematic view of elements in a laser scanner according to an embodiment;

5B FIG. 3 is a flowchart showing a method of operating a scanner according to an embodiment; FIG.

6 a schematic plan view of a scanner according to another embodiment of the invention;

7 FIG. 3 is a flowchart showing a method of operating the scanner according to an embodiment; FIG.

8A and 8B Fig. 3: perspective views of a scanner used in conjunction with a remote probe device according to an embodiment of the invention;

9 : A flow chart illustrating a procedure for operating the scanner from 5 shows;

10 a schematic plan view of a scanner according to an embodiment;

11 : A flow chart illustrating a procedure for operating the scanner from 10 shows; and

12 FIG. 3 is a flowchart showing a diagnostic method according to an embodiment. FIG.

The detailed description explains embodiments of the invention together with the advantages and features by way of example with reference to the drawings.

Detailed description of the invention

Embodiments of the present invention provide advantages by increasing the reliability and accuracy of three-dimensional coordinates of a data point cloud detected by a scanner. Embodiments of the invention provide advantages in that they detect anomalies in captured data and automatically adjust the operation of the scanner to capture the desired results. Embodiments of the invention offer advantages in that they detect anomalies in the captured data and provide the operator with an indication of areas where additional data acquisition is required. Still other embodiments of the invention offer advantages in that they detect anomalies in the captured data and provide the operator with an indication of where additional data acquisition with a remote probe can be detected.

Scanner devices capture three-dimensional coordinate data of objects. In one embodiment, a scanner has 20 who in 1 is shown, a housing 22 that's a first camera 24 , a second camera 26 and a projector 28 includes. The projector 28 emits light 30 on a surface 32 an object 34 , In the exemplary embodiment, the projector uses 28 a visible light emitting light source illuminating a pattern generator. The visible light emitting light source may be, for example, a laser, a superluminescent diode, an incandescent lamp, a xenon lamp, a light emitting diode (LED) or other lighting device. In one embodiment, the pattern generator is a chrome mask with a patterned light pattern etched on it. The photomask may have a single pattern or patterns that move in and out of position as needed. The photomask can be installed manually or automatically in the operating position. In other embodiments, the source pattern may be a light produced by a digital micro-mirror device (DMD) such as a digital light projector (DLP) manufactured by Texas Instruments Corporation, a liquid crystal display (LCD), a liquid crystal on silicon (LCOS) device or similar device used in the transmission mode instead of the reflection mode is reflected or transmitted. The projector 28 can also be a lens system 36 include that changes the exiting light to cover the desired area.

The projector 28 is configurable in this embodiment so that it structured light over a range 37 emitted. As used herein, the term "structured light" refers to a two-dimensional light pattern projected onto an area of an object that conveys information that can be used to determine the coordinates of points on the object. In one embodiment, a patterned light pattern includes at least three non-collinear pattern elements disposed in the region. Each of the three non-collinear pattern elements conveys information that can be used to determine the point coordinates. In another embodiment, a projector is provided that is configurable to project both a region pattern and a line pattern. The projector in one embodiment is a digital micromirror device (DMD) configured to switch between the two back and forth. In one embodiment, the DMD projector may also reciprocate a line or reciprocate a point in a raster pattern.

There are generally two types of structured light patterns, namely a coded light pattern and an uncoded light pattern. A coded light pattern as used herein is one in which the three-dimensional coordinates of an illuminated surface of the object are determined by taking a still image. It is possible with a coded light pattern to obtain and register point cloud data while the projection device is moving relative to the object. One type of coded light pattern includes a set of elements (eg, geometric shapes) arranged in lines, with at least three of the elements being non-collinear. Such pattern elements are recognizable because of their arrangement.

In contrast, an uncoded structured light pattern as used herein is a pattern that does not allow measurement by a single pattern. A series of uncoded light patterns can be sequentially projected and captured. In this case, the projector must normally be held stationary relative to the object.

It is understood that the scanner 20 either a coded or an uncoded one use structured light pattern. The patterned light pattern may include the patterns disclosed in the journal article "DLP-Based Structured Light 3D Imaging Technologies and Applications" by Jason Geng, published in SPIE Session Reports, Vol. 7932. Further, the projector sends 28 in some embodiments described below, a pattern formed from a reciprocating light line or a reciprocating light spot. Floating light lines and points offer advantages over light areas in identifying some types of anomalies such as multipath interference. Automatically moving the line while keeping the scanner stationary also provides advantages in providing smoother sampling of surface points.

The first camera 24 includes a photosensitive sensor 44 , which is a digital image or a digital representation of the area 48 generated in the field of view of the sensor. The sensor may be a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) sensor having, for example, a pixel array. The first camera 24 may also include other components such as a lens 46 and other optical devices include, but are not limited to. The Lens 46 has a first focal length assigned to it. The sensor 44 and the lens 46 interact and define a first field of view "X". In the exemplary embodiment, the first field of view "X" is 16 degrees (0.28 cm per cm).

Similarly, the second camera includes 26 a photosensitive sensor 38 , which is a digital image or a digital representation of the area 40 generated in the field of view of the sensor. The sensor may be a charge-coupled device (CCD) type sensor or a complementary metal oxide semiconductor (CMOS) type sensor having, for example, a pixel array. The second camera 26 may also include other components such as a lens 42 and other optical devices include, but are not limited to. The Lens 42 has a second focal length associated therewith, the second focal length being different from the first focal length. The sensor 38 and the lens 42 interact and define a second field of view "Y". In the exemplary embodiment, the second field of view "Y" is 50 degrees (0.85 cm per cm). The second field of view Y is larger than the first field of view X. Accordingly, the range 40 bigger than the area 48 , It is understood that a larger field of view allows for faster acquisition and measurement of a particular area of the object surface 32 permits; when the photosensitive arrangements 44 and 38 have the same number of pixels, however, a smaller field of view gives a higher resolution.

The projector 28 and the first camera 24 are arranged in a fixed relationship in an angle in the exemplary embodiment in such an angle that the sensor 44 Light can catch that from the surface of the object 34 is reflected. Likewise are the projector 28 and the second camera 26 arranged in fixed relationship at an angle such that the sensor 38 Light can catch that from the surface 32 of the object 34 is reflected. Because the projector 28 , the first camera 24 and the second camera 26 Having fixed geometric relationships, the distance and coordinates of points on the surface can be determined by their trigonometric relationships. Although the fields of view (FOV; fields-of-view) of the cameras 24 and 26 in 1 are not overlapping, they may overlap partially or completely.

The projector 28 and the cameras 24 . 26 are electrically connected to a control device 50 coupled in the housing 22 is arranged. The control device 50 may include one or more microprocessors, digital signal processors, memory and signal conditioning circuits. The scanner 20 may further include actuators (not shown) that may be manually turned on by the operator to facilitate operation and data collection by the scanner 20 to start. In one embodiment, the image processing for determining the x, y, z coordinate data becomes the surface 32 of the object 34 representing point cloud by the control device 50 carried out. The coordinate data may be local, such as in volatile or nonvolatile memory 54 get saved. The memory may be removable, such as a memory stick or a memory card. The scanner 20 has a communication circuit in other embodiments 52 that allows him to transfer the coordinate data to a remote processing system 56 transferred to. The communication medium 58 between the scanner 20 and the remote processing system 56 can be wired (for example, Ethernet) or wireless (for example, Bluetooth, IEEE 802.11). In one embodiment, the coordinate data is provided by the remote processing system 56 based on the images taken by the scanner 20 over the communication medium 58 be transmitted.

A relative movement between the object surface 32 and the scanner 20 is possible as it is by the bidirectional arrow 47 is shown. There are several ways in which such relative movement can be provided. In one embodiment, the scanner is in the hand held scanner and is the object 34 fixed. The relative movement results from moving the scanner over the object surface. In another embodiment, the scanner is attached to an effector at a robot end. The relative movement is provided by the robot as it moves the scanner over the object surface. In another embodiment, either the scanner 20 or the object 34 attached to a moving mechanical mechanism such as a gantry coordinate measuring machine or an articulated arm CMM. The relative movement is provided by the moving mechanical mechanism while holding the scanner 20 moved over the object surface. In some embodiments, the movement is provided by the operator's action and in other embodiments, the movement is provided by a mechanism that is controlled by a computer.

Now referring to 2 , will the operation of the scanner 20 according to a method 1260 described. As in block 1262 shown, the projector emits 28 first a structured light pattern on the area 37 the surface 32 of the object 34 , The light 30 of the projector 28 gets off the surface 32 as reflected light 62 reflected by the second camera 26 is caught. The three-dimensional profile of the surface 32 influences this from the photosensitive arrangement 38 in the second camera 26 taken picture of the pattern. Using the information gathered from one or more images of the pattern (s), the controller determines 50 or the remote processing system 56 a one-to-one correspondence between the pixels of the photosensitive array 38 and from the projector 28 emitted light pattern. Using this one-to-one correspondence, triangulation principles are used to obtain the three-dimensional coordinates of points on the surface 32 to investigate. This acquisition of three-dimensional coordinate data (point cloud data) is in block 1264 shown. By moving the scanner 20 over the surface 32 can be a point cloud of the entire object 34 to be created.

During the scanning process, the control device 50 or the remote processing system 56 detect an undesirable condition or problem with the point cloud data, as in block 1266 shown. Methods for detecting such a problem are described below with reference to FIG 12 described. The detected problem may be, for example, an error in or lack of point cloud data in a particular area. This error in or lack of data can be caused by too little or too much reflected light from this area. For example, too little or too much reflected light may result from a difference in reflectance across the object surface, from high or varying angles of incidence of the light 30 on the object surface 32 or from low reflection (black or translucent) materials or shiny surfaces. Certain points on the object may be angled such that they produce a very bright directional reflection known as glitter.

Another possible cause of error in or lack of point cloud data is poor resolution in areas of fine features, sharp edges, or rapid changes in depth. Such a defective resolution can result, for example, from a hole.

Another possible cause of an error in or lack of point cloud data is a multipath failure. A beam of light from the projector 28 usually emits a point on the surface 32 and is scattered over an angular range. The scattered light is from the lens 42 the camera 26 on a small spot on the photosensitive array 38 displayed. Accordingly, the scattered light from the lens 46 the camera 24 on a small spot on the photosensitive array 44 be imaged. A multipath fault occurs when that's the point on the surface 32 reaching light not only from the light beam of the projector 28 but also from secondary light coming from another section of the surface 32 is reflected. Such a secondary light may be that of the photosensitive array 38 . 44 interfere with captured light patterns and thereby prevent accurate determination of three-dimensional coordinates of the spot. Methods for identifying an existing multipath interference are described in the present application with reference to FIG 12 described.

When the control device in block 1266 determines that the point cloud is OK, the process is terminated. Otherwise, in block 1268 a determination of whether the scanner is being used in manual or automatic mode. If the mode is manual, the operator is in block 1270 instructed to move the scanner to the desired position.

There are numerous ways to display the movement desired by the operator. In one embodiment, indicator lights on the scanner body indicate the desired direction of movement. In another embodiment, a light is projected onto the surface indicating the direction in which the operator must move. Further, a color of the projected light may indicate whether the scanner is too close to the object or too far from the object Object is removed. In a further embodiment, a display of the area on which the operator has to project the light takes place. Such a display may be a graphical representation of point cloud data, a CAD model, or a combination of the two. The display may be displayed on a computer monitor or on a display device built into the scanner device.

In any of these embodiments, a method for determining the approximate position of the scanner is intended. The scanner may in one case be attached to an articulated arm CMM using angular encoders in its joints to determine the position and orientation of the scanner mounted at its end. In another case, the scanner includes inertial sensors located in the device. Inertial sensors may be, for example, gyroscopes, accelerometers and magnetometers. Another method of determining the approximate position of the scanner is to illuminate photogrammetric points located as landmarks on or around the object. In this way, the far-field camera in the scanner can determine its approximate position relative to the object.

In another embodiment, a CAD model on a computer screen indicates the areas where additional measurements are desired, and the operator moves the scanner to the features on the scanner according to the fit of the features on the object. By updating the CAD model on the screen during a scan, the operator can be given quick feedback on whether the desired areas of the part have been measured.

After the operator has moved the scanner into position, it is done in block 1272 a measurement with the small field of view having camera 24 , By looking at a relatively smaller area in block 1272 the resolution of the resulting three-dimensional coordinates is improved and better performance is provided to characterize features such as holes and edges.

Since the near-vision field camera sees a relatively smaller area than the far-field camera, the projector can 28 illuminate a relatively smaller area. This provides advantages in eliminating multipath interference because there are relatively fewer illuminated spots on the object that can reflect light back onto the object. A smaller illuminated area may also facilitate the control of the exposure time to obtain the optimum amount of light for a given reflectance and angle of incidence of the object under test. If in block 1274 all points have been captured, the process ends at block 1276 ; otherwise it will continue.

In an embodiment where the mode is from block 1268 is automatic, the automatic mechanism then moves the scanner into block 1278 in the desired position. The automatic mechanism, in some embodiments, has sensors for providing information about the relative position of the scanner and the test object. In an embodiment where the automatic mechanism is a robot, angle gauges in the robotic joints provide information about the position and orientation of the effector at the robot end used to hold the scanner. In an embodiment where the object is moved by another type of automatic mechanism, linear encoders or various other sensors may provide information about the relative position of the object and the scanner.

After the automatic mechanism has moved the scanner or object into position, then in block 1280 performed three-dimensional measurements with the camera having a small field of view. Such measurements are made by block 1282 repeatedly until all measurements are completed, and the process ends at block 1284 ,

The projector 28 changed in one embodiment, the structured light pattern when the scanner from the data acquisition with the second camera 26 to the first camera 24 switches. In another embodiment, the same patterned light pattern is used with both cameras 24 . 26 used. In yet another embodiment, the projector emits 28 a pattern formed by a reciprocating line or a reciprocating point when the data from the first camera 24 be recorded. After the data acquisition with the first camera 24 the method is scanned by the second camera 26 continued. This process continues until the operator has scanned the desired area of the part.

It is understood that, although the procedure of 2 is shown as a linear or sequential method, in other embodiments, one or more of the illustrated steps can be performed in parallel. At the in 2 In the illustrated method, the method involved first measuring the entire object and then performing further detailed measurements according to an evaluation of the acquired point cloud data. An alternative use of the scanner 20 This involves measuring detailed or critical areas using the camera 24 to begin with, which has the small field of view.

It will also be understood that in existing scanning systems, it is common practice to provide a way of replacing the camera lens or projector lens as a way of changing the field of view of the camera or projector in the scanning system. However, such changes are time consuming and usually require an additional compensation step in which an object such as a point plate is placed in front of the camera or projector to determine the aberration correction parameters for the camera or projector system. Thus, a scanning system that offers two cameras with different fields of view such as the cameras 24 . 26 from 1 provides a significant advantage in measurement speed while providing the scanner with a fully automatic mode.

In 3 is another embodiment of a scanner 20 with a housing 22 represented, which is a first coordinate detection system 76 and a second coordinate detection system 78 includes. The first coordinate acquisition system 76 includes a first projector 80 and a first camera 82 , Similar to the design of 1 the projector emits 80 a light 84 on a surface 32 an object 34 , In the exemplary embodiment, the projector uses 80 a visible light emitting light source illuminating a pattern generator. The visible light emitting light source may be, for example, a laser, a super-luminescent diode, a light bulb, a light emitting diode (LED) or other lighting device. In one embodiment, the pattern generator is a chrome mask with a patterned light pattern etched on it. The photomask may have a single pattern or patterns that move in and out of position as needed. The photomask can be installed manually or automatically in the operating position. In other embodiments, the source pattern may be a light generated by a digital micromirror device (DMD) such as a digital light projector (DLP) manufactured by Texas Instruments Corporation, a liquid crystal display (LCD), a liquid crystal on silicon device (LCOS ) or a similar device used in the transmission mode instead of the reflection mode is reflected or transmitted. The projector 80 can also be a lens system 86 include that changes the exiting light to have the desired focal characteristics.

The first camera 82 includes a sensor 88 the photosensitive array, which is a digital image or a digital representation of the area 90 generated in the field of view of the sensor. The sensor may be a charge-coupled device (CCD) type sensor or a complementary metal oxide semiconductor (CMOS) type sensor having, for example, a pixel array. The first camera 82 may also include other components such as a lens 92 and other optical devices include, but are not limited to. The first projector 80 and the first camera 82 are arranged in fixed relationship at an angle such that the first camera 82 light 85 of the first projector 80 can capture that from the surface 32 of the object 34 is reflected. It is understood that, because the first camera 92 and the first projector 80 are arranged in fixed relationship, the principles of trigonometry discussed above for determining the coordinates of points on the surface 32 in the area 90 can be used. Even though 3 for the sake of clarity with the first camera 82 near the first projector 80 pictured, it is understood that the camera is closer to the other side of the case 22 could be arranged. Are you spacing the first camera? 82 and the first projector 80 further apart, one can assume that the accuracy of the 3D measurement is improved.

The second coordinate acquisition system 78 includes a second projector 94 and a second camera 96 , The projector 94 has a light source that may include a laser, a light emitting diode (LED), a superluminescent diode (SLED), a xenon lamp, or other suitable light source type. A lens 98 is used in an embodiment for focusing the intercepted light coming from the laser light source to a light line 100 and may include one or more cylindrical lenses or lenses of various other shapes. The lens is also referred to herein as a "lens system" because it may comprise one or more individual lenses or a collection of lenses. The light line is essentially straight, that is, the maximum deviation from a line is less than 1% of its length. A type of lens used by an embodiment is a rod lens. Rod lenses typically have the shape of a solid cylinder made of glass or plastic, polished at its periphery and ground at both ends. Such lenses convert collimated light passing through the diameter of the rod into a line. Another lens type that you can use is a cylindrical lens. A cylindrical lens is a lens that has the shape of a sub-cylinder. For example, one surface of a cylindrical lens may be flat while the opposite surface is cylindrical.

In another embodiment, the projector generates 94 a two-dimensional light pattern that covers an area of the surface 32 covers. The resulting coordinate acquisition system 78 is then called a "structured light scanner".

The second camera 96 includes a sensor 102 such as a charge coupled device (CCD) type sensor or a complementary metal oxide semiconductor (CMOS) type sensor. The second camera 96 may also include other components such as a lens 104 and other optical devices include, but are not limited to. The second projector 94 and the second camera 96 are arranged at an angle such that the second camera 96 light 106 of the second projector 94 can capture that from the object 34 is reflected. It is understood that, because the second projector 94 and the second camera 96 are arranged in fixed relationship, the principles of trigonometry discussed above for determining the coordinates of points on the surface 32 on the light 100 formed line can be used. It is also understood that the camera 96 and the projector 94 on opposite sides of the housing 22 can be arranged to improve the 3D measurement accuracy.

In another embodiment, the second coordinate detection system is configured to project various patterns including not only a fixed line of light but also a reciprocating line of light, a reciprocating point of light, a coded pattern of light (covering an area), or successive ones Patterns (which cover an area) can be. Each type of projection pattern has different advantages, such as speed, accuracy, and insensitivity to multipath interference. By evaluating the performance requirements for each particular measurement and / or by reviewing the characteristics of the returned data or the expected object shape (from CAD models or from a 3D reconstruction based on the acquired scan data), it is possible to select the type of projected pattern, which optimizes the performance.

In a further embodiment, the distance between the second coordinate detection system 78 and the object surface 32 other than the distance between the first coordinate detection system 76 and the object surface 32 , For example, the camera 96 closer to the object 32 be positioned as the camera 88 , In this way, the resolution and the accuracy of the second coordinate detection system 78 relative to that of the first coordinate detection system 76 be improved. It is helpful in many cases, quickly a relatively large and smooth object with a lower resolution system 76 and then details including edges and holes with a higher resolution system 78 scan.

A scanner 20 can be used in manual or automatic mode. In manual mode, an operator is prompted to move the scanner closer to the object surface, or to move further away from the object surface, in accordance with the sensing system used. In addition, the scanner can 20 projecting a beam of light or pattern of light that indicates to the operator the direction in which the scanner is to be moved. Alternatively, indicator lights on the device may indicate the direction in which the scanner should be moved. In automatic mode, the scanner can 20 or the object 34 automatically moved relative to each other according to the requirements of the measurement.

Similar to the design of 1 are the first coordinate acquisition system 76 and the second coordinate detection system 78 electrically to a control device 50 coupled in the housing 22 is arranged. The control device 50 may include one or more microprocessors, digital signal processors, memory and signal conditioning circuits. The scanner 20 may further include actuators (not shown) that may be manually turned on by the operator to facilitate operation and data collection by the scanner 20 to start. In one embodiment, the image processing for determining the x, y, z coordinate data becomes the surface 32 of the object 34 representing point cloud by the control device 50 carried out. The coordinate data may be local, such as in volatile or nonvolatile memory 54 get saved. The memory may be removable, such as a memory stick or a memory card. The scanner 20 has a communication circuit in other embodiments 52 that allows him to transfer the coordinate data to a remote processing system 56 transferred to. The communication medium 58 between the scanner 20 and the remote processing system 56 can be wired (for example, Ethernet) or wireless (for example, Bluetooth, IEEE 802.11). In one embodiment, the coordinate data is provided by the remote processing system 56 Detects and transmits the scanner 20 taken pictures via the communication medium 58 ,

Now referring to 4 , the procedure becomes 1400 to operate the scanner 20 from 3 described. In block 1402 the first projector emits 80 of the first coordinate acquisition system 76 of the scanner 20 a textured light pattern on the area 90 the surface 32 of the object 34 , The light 84 of the projector 80 gets off the surface 32 reflected and the reflected light 85 is from the first camera 82 collected. As discussed above, changes in the surface profile create the surface 32 Distortions in the pictured light pattern, that of the first Photosensitive arrangement 88 is caught. Since the pattern is formed by patterned light, a light line, or a light spot, in some cases it is for the control device 50 or the remote processing system 56 possible, a one-to-one correspondence between points on the surface 32 and the pixels in the photosensitive array 88 to investigate. This allows the use of the above-discussed triangulation principles in block 1404 to obtain point cloud data, ie the x, y, z coordinates of points on the surface 32 to investigate. By moving the scanner 20 relative to the surface 32 can be a point cloud of the entire object 34 to be created.

In block 1406 determines the control device 50 or the remote processing system 56 Whether the point cloud data has the desired data quality attributes or if there is a potential problem. The types of problems that can occur were described above with reference to 2 This discussion will not be repeated here. When the control device in block 1406 determines that the point cloud has the desired data quality attributes, the process is terminated. Otherwise, in block 1408 a determination of whether the scanner is being used in manual or automatic mode. If the mode is manual, the operator is in block 1410 instructed to move the scanner to the desired position.

There are several ways to indicate the desired movement by the operator, as described above with reference to 2 has been described. This discussion will not be repeated here.

To instruct the operator to achieve the desired movement requires a method to determine the approximate position of the scanner. As based on 2 has been explained, methods can be the attachment of the scanner 20 on an articulated arm CMM, the use of inertial sensors in the scanner 20 which include illumination of photogrammetric points or the adaptation of features to a displayed image.

After the operator has moved the scanner into position, it is done in block 1412 a measurement with the second coordinate detection system 78 , By using the second coordinate acquisition system, resolution and accuracy can be improved or problems eliminated. If in block 1414 all points have been captured, the process ends at block 1416 ; otherwise it will continue.

When the operation mode from block 1408 is automatic, then the automatic mechanism moves into block 1418 the scanner in the desired position. An automatic mechanism, in most cases, has sensors that provide information about the relative position of the scanner and test object. In the case where the automatic mechanism is a robot, angle gauges in the robot joints provide information about the position and orientation of the robot end effector used to hold the scanner. For other types of automatic mechanisms, linear encoders or various other sensors can provide information about the relative position of the object and the scanner.

After the automatic mechanism has moved the scanner or object into position, then in block 1420 three-dimensional measurements with the second coordinate acquisition system 78 carried out. Such measurements are made by block 1422 repeatedly until all measurements are completed. The process ends at block 1424 ,

It is understood that, although the procedure of 4 is shown as a linear or sequential method, in other embodiments, one or more of the illustrated steps can be performed in parallel. At the in 4 In the illustrated method, the method involved first measuring the entire object and then performing further detailed measurements according to an evaluation of the acquired point cloud data. An alternative use of the scanner 20 This involves measuring detailed or critical areas using the second coordinate acquisition system 78 to start.

It should also be understood that in existing scanning systems, it is common practice to provide a way of replacing the camera lens or projector lens as a way to change the field of view of the camera or projector in the scanning system. However, such changes are time consuming and usually require an additional compensation step in which an object such as a point plate is placed in front of the camera or projector to determine the aberration correction parameters for the camera or projector system. Thus, a system offers two different coordinate acquisition systems, such as the scanning system 20 from 3 provides a significant advantage in measurement speed while providing the scanner with a fully automatic mode.

When performing scanner measurements, an error may occur due to multipath interference. The origin of a multipath fault will now be discussed and a first method for the Elimination or reduction of a multipath disorder described.

The case of multipath interference occurs when a portion of the light that illuminates the object surface is first scattered from another surface of the object before returning to the camera. For the point on the object that picks up this scattered light, the light sent to the photosensitive array is then not only the light projected directly from the projector, but also the light sent to another point on the projector and scattered by the object. The result of the multipath interference, especially in the case of scanners that project a two-dimensional (structured) light, may result in the calculated distance between the projector and the object surface being inaccurate at this point.

A case of a multipath fault is determined by 5A illustrates, wherein in this embodiment, a scanner 4570 a line of light 4525 on the surface 4510A of an object. The light line 4525 runs perpendicular to the paper plane. In one embodiment, the rows of a photosensitive array are parallel to the paper plane and the columns are perpendicular to the paper plane. Each line represents a point on the projected line 4525 in the direction perpendicular to the paper plane direction. The distance between the projector and the object is determined for this point on the line by first calculating the centroid for each line. At the surface point 4526 becomes the centroid on the photosensitive array 4541 through the point 4546 represents.

The position 4546 of the centroid on the photosensitive array may be used to calculate the distance between the perspective center 4544 the camera and the object point 4526 be used. This calculation is based on trigonometric relations according to the principles of triangulation. To perform these calculations, the baseline distance D between the perspective center 4544 the camera and the perspective center 4523 required by the projector. Furthermore, the relative orientation of the projector system 4520 to the camera system 4540 be known.

To understand the error caused by multipath interference, consider the point 4527 , Light that is reflected or scattered from this point is transmitted through the lens 4542 on the point 4548 on the photosensitive array 4541 displayed. In addition to the light that came directly from the projector and caught from the point 4527 is scattered, but gets further light from the point 4526 to the point 4527 reflected before being imaged on the photosensitive array. The light is likely to be scattered to an unexpected position, resulting in the formation of two centroids in a particular row. As a result, observing two centroids in a particular row is a good indicator of the presence of multipath interference.

In the case of the structured light projected onto an area of the object surface, there is a secondary reflection from a point such as, for example 4527 usually not as obvious as with light being projected onto a line and therefore more likely to cause an error in the measured 3D surface coordinates.

The lighting pattern can be changed by placing a projector with an adjustable lighting pattern on a display element 4521 used. The display element 4521 could be a digital micromechanical mirror (DMM) such as a Digital Light Projector (DLP). Such devices include a plurality of small mirrors that are rapidly adjustable by means of an electrical signal to quickly adjust a lighting pattern. Other devices which can form an electrically adjustable display pattern include an LCD display device (liquid crystal display device) and a LCOS display device (liquid crystal on silicon display device).

One way to test multipath interference in a system that projects structured light over a range is to replace the light-line projection display device. The presence of multiple centroids in a row indicates that multipath interference exists. By flicking the light line, an area can be covered without having to move the probe by an operator.

The light line can be adjusted to any desired angle by an electrically adjustable display device. In many cases, multipath interference can be eliminated by changing the direction of the projected light line.

For surfaces having many wrinkle angles and steep angles such that reflections are difficult to avoid, the electrically adjustable display device can be used to reciprocate a spot of light. In some cases, a secondary reflection may arise from a single point of light, but it is usually relatively easy to determine which of the reflected points of light is valid.

An electrically adjustable display device can also be used to quickly switch between a coded and an uncoded pattern. In most cases, a coded pattern is used to perform a 3D measurement based on a single frame of camera information. On the other hand, multiple patterns (consecutive or uncoded patterns) may be used to achieve greater accuracy in the measured 3D coordinate values.

In the past, electrically adjustable display devices have been used to project each of a series of patterns in successive patterns - for example, a series of gray line patterns and then a sequence of sinusoidal patterns each having a different phase.

The present inventive method offers advantages over prior methods in selecting those methods which identify or eliminate problems such as multipath interference and which indicate whether a single-shot pattern (e.g., a coded pattern) or multiple-shot pattern is preferred to achieve the required accuracy so quickly as possible.

In the case of a line scanner, there is often a way to determine the presence of multipath interference. In the absence of multipath interference, the light reflected from a point on the object surface is imaged in a single line on a contiguous pixel area. If there are two or more areas of a line that capture a significant amount of light, then a multipath fault will be displayed. In 5A an example of such a multipath interference condition and the resulting extra illumination area on the photosensitive array is shown. The surface 4510A now has a larger curvature near the intersection 4526 , The surface normal at the intersection is the line 4528 and the angle of incidence is 4531 , The direction of the reflected light line 4529 becomes from the reflection angle 4532 determined, which is equal to the angle of incidence. As indicated above, the light line represents 4529 actually an overall direction for the light that is scattered over an angular range. The center of the scattered light hits the surface 4510A at the point 4527 on top of that by the lens 4544 at the point 4548 is imaged on the photosensitive array. The unexpectedly high amount of light that is near the point 4548 is caught, indicates that there is likely to be a multipath fault. In a line scanner, the primary importance of multipath interference is not in the 5A presented case where the two points 4546 and 4527 are a considerable distance apart and can be analyzed separately, but rather in the case where the two points overlap or merge with each other. In this case, it may not be possible to determine the area centroid corresponding to the desired point, which is in 15E the point 4546 equivalent. In the case of a scanner projecting light over a two-dimensional area, the problem becomes even greater, as when re-examining 5A can be seen. All light would be on the photosensitive array 4541 is needed for the determination of two-dimensional coordinates, it is then clear that the light is at the point 4527 the desired light pattern projected directly from the projector, and the unwanted light from the object surface to the spot 4527 is reflected, would correspond. As a result, in this case would likely for the point 4527 calculates the wrong three-dimensional coordinates for the light projected over a range.

In a projected light line, it is possible in many cases to eliminate multipath interference by changing the direction of the line. One possibility is to use a line scanner that uses a projector with inherent two-dimensional capability, which allows the line to be moved back and forth or automatically rotated in different directions. An example of such a projector is a projector using a digital micromirror (DMD) as discussed above. For example, if multipath interference is suspected in a particular scan obtained with structured light, a measurement system could be automatically configured to switch to a measurement method that uses a reciprocated light line.

Another method of reducing, minimizing, or eliminating multipath interference is to reciprocate a light spot, rather than a light line or a light area, over those areas where multipath interference has been indicated. By illuminating a single spot of light, it is usually easy to identify any light that has been scattered by a secondary reflection.

The determination of the desired pattern, which is projected by an electrically adjustable display device, benefits from a diagnostic analysis, which is described below with reference to FIG 12 is described.

The variation in the pattern of the projected light, in addition to its use in diagnostics and corrections for multipath interference, also provides advantages in providing required accuracy and resolution in a minimum amount of time. In one embodiment, a measurement first performed by projecting a coded light pattern in a single shot onto an object. The three-dimensional coordinates of the surface are determined using the acquired data and the results are analyzed to see if any areas have holes, edges, or features that require more detailed analysis. Such a detailed analysis could be done, for example, by using the narrow field camera 24 from 1 or the high-resolution scanner system 78 from 3 used.

The coordinates are also analyzed to determine the approximate distance to the target, thereby providing a starting distance for a more accurate measurement method, such as a. For example, a method is provided wherein, as discussed above, successive sinusoidal out-of-phase light patterns are projected onto a surface. Obtaining with the coded light pattern a starting distance for each point on the surface eliminates the requirement to obtain this information by varying the pitch for multiple sinusoidal phase-shifted samples, thereby saving considerable time.

Now referring to 5B , there is shown a design that overcomes the anomalies or accuracy of the scanner 20 recorded coordinate data can be improved. The procedure 211 starts in block 212 by scanning an object such as an object 34 with a scanner 20 , The scanner 20 may be a scanner such as those used in the embodiments of 1 . 3 . 5 and 7 described that have at least one projector and a camera. In this embodiment, the scanner projects 20 in block 212 a first light pattern on the object. In one embodiment, this first light pattern is a coded structured light pattern. The procedure 211 recorded and determined in block 214 the three-dimensional coordinate data. The coordinate data is in the query block 216 analyzed to determine if there are any anomalies such as the above-mentioned multipath interference, a low resolution around an element, or the lack of data due to changes in surface angles or surface reflectance. If an anomaly is detected, the procedure goes 211 with block 218 where the pattern of light emitted by the projector is changed to a second pattern of light. In one embodiment, the second pattern of light is a reciprocating line of light.

After the projection of the second light pattern, the procedure goes 211 with block 220 where the three-dimensional coordinate data is collected and determined for the area where the anomaly was detected. The procedure 211 returns to the query block 216 back, where it is determined if the anomaly has been resolved. If the query block 216 still detects an anomaly or a lack of accuracy or resolution, the process returns to block 218 back and switch to a third light pattern. The third light pattern in one embodiment is a sequential sinusoidal phase shift pattern. In another embodiment, the third light pattern is a reciprocating light spot. This iterative method continues until the anomaly has been resolved. Once the coordinate data from the area of the anomaly has been determined, the procedure goes 211 with block 222 where the emitted pattern returns to the first patterned light pattern and the scanning process continues. The procedure 211 continues until the operator has scanned the desired area of the object. In the case where the with the method of 11 obtained sampling information is unsatisfactory, one can apply a measuring task with a probe as discussed herein.

Now referring to 6 , is there another embodiment of a scanner 20 shown attached to a movable device 120 is appropriate. The scanner 20 has at least one projector 122 and at least one camera 124 , which are arranged in a fixed geometric relationship such that the principles of trigonometry for the determination of the three-dimensional coordinates of points on the surface 32 can be used. The scanner 20 For example, the same scanner as the one based on 1 or 3 be described. In one embodiment, the scanner is the same as the scanner of 10 with a probe. The in the embodiment of 6 however, the scanner used may be any scanner, such as a structured light scanner, or a line scanner, such as a scanner disclosed in commonly assigned U.S. Patent 7,246,030, filed January 18, 2006, entitled "Portable Coordinate Measurement Machine with Integrated Line Laser Scanner "is revealed. In another embodiment of the in the embodiment of 6 The scanner used a structured light scanner that projects light over an area onto an object.

The mobile device 120 In the exemplary embodiment, a robotic device is the automatic movement with arm segments 126 . 128 provides that by turning and pivoting joints 130 interconnected to the movement of the arm segments 126 . 128 to allow, which results in that the scanner 20 moved from a first position to a second position (as indicated by the dashed line in FIG 6 is displayed). The mobile device 120 can be actuators such as motors (not shown) connected to the arm segments 126 . 128 are coupled to the arm segments 126 . 128 to move from the first to the second position. It is understood that a movable device 120 with articulated arms for the purpose of illustration and the claimed invention should not be so limited. In other embodiments, the scanner 20 be attached to a movable device that moves him, for example, over rails, wheels, tracks, belts or ropes or a combination of the foregoing. In other embodiments, the robot has a different number of arm segments.

The moveable device in one embodiment is an articulated arm CMM such as that described in U.S. Patent Application Serial No. 13 / 491,176 filed January 20, 1984, of the same assignee. In this embodiment, the movement of the scanner 20 from the first to the second position, the operator has the arm segments 126 . 128 moved manually.

In an embodiment with an automatic device, the movable device comprises 120 furthermore a control device 132 which is configured to turn on the actuators to the arm segments 126 . 128 to move. The control device 132 communicates with a controller in one embodiment 134 , As will be discussed in more detail below, this arrangement allows the control device 132 moving the scanner in response to an anomaly in the collected data 20 , It is understood that the control devices 132 . 134 can be incorporated into a single processing unit or the functionality can be distributed to multiple processing units.

By conducting an analysis on the basis of 12 is it possible to use the scanner 20 be positioned and oriented so that the desired measurement results are achieved. In some embodiments, a measured feature may benefit from a desired direction of the scanner. The measurement of the diameter of a hole can be improved, for example, by the scanner camera 124 is oriented so that it is approximately perpendicular to the hole. In other embodiments, a scanner may be arranged to reduce or minimize the possibility of multipath interference. Such an analysis may be based on a CAD model available as part of the diagnostic method, or it may be based on data acquired by the scanner in an initial position before a second movement of the scanner 20 through the device 120 he follows.

Now referring to 7 , will the operation of the scanner 20 and the movable device 120 described. The procedure starts at block 136 with the scanning of the object 34 with the scanner 20 in the first position. The scanner 20 recorded and determined in block 138 Coordinate data of points on the surface 32 of the object 34 , It is understood that the movable device 120 the scanner 20 can move to capture data about surface points in a desired area. It will be in the query block 140 determines if there is an anomaly in the coordinate data at point 142 such as a multipath interference, or if the direction needs to be changed to achieve improved resolution or measurement accuracy. It is understood that the point 142 from 6 a single point, a line of points or an area of the surface 32 can represent. If an anomaly or a need for improved accuracy is detected, the method goes to block 144 continue where the moving device 120 the position of the scanner 20 for example, moving from the first to the second position and the area of interest in block 146 rescans to capture three-dimensional coordinate data. The process returns to the query block 140 back, where it is determined whether there is still an anomaly in the coordinate data or whether an improvement of the measurement accuracy is desired. The scanner 20 is moved again in these cases and the process continues until the measurement results reach a desired level. Once the coordinate data is obtained, the procedure goes from the query block 140 to block 148 continue where the scanning process continues until the desired area is scanned.

In embodiments in which the scanner 20 a probe ( 10 ), the movement of the scanner from the first to the second position may be arranged to contact the areas of interest with the probe. Because the position of the scanner and thus the probe from the position and orientation of the arm segments 126 . 128 can be determined, the three-dimensional coordinates of the point on the surface can be 32 determine.

In some embodiments, those with the scanner 20 from 8A . 8B may be corrupted by a multipath interference. In other cases, the measurement results may not provide the desired resolution or accuracy for the correct measurement of some surface characteristics 32 such as edges, holes or complex features. In these cases, it may be desirable for an operator to have a remote probe 152 used to points or areas on the surface 32 query. The scanner 20 includes at a in 8A . 8B illustrated embodiment a projector 156 and cameras 154 . 155 which are at an angle relative to the projector 156 are arranged that from the projector 156 emitted light from the surface 32 reflected and from one or both of the cameras 154 . 155 is caught. The projector 156 and the cameras 154 . 156 are arranged in a fixed geometrical relationship so that the principles of trigonometry can be used to determine the three-dimensional coordinates of points on the surface 32 to investigate.

The projector 156 In one embodiment, it is configured to have a visible light 157 on a field of interest 159 on the surface 32 of the object 34 to emit as it is in 8A is shown. The three-dimensional coordinates of the illuminated area of interest 159 can be confirmed by the image of the illuminated area 159 one or both cameras 154 . 155 is used.

The scanner 20 is configured with the remote probe 152 cooperate such that an operator a probe tip 166 with the object surface 132 at the illuminated area of interest 159 can bring in contact. In one embodiment, the remote probe comprises 152 at least three non-collinear points of light 168 , The points of light 168 For example, light spots generated by, for example, light emitting diodes (LEDs) or reflective spots of light emitted from an infrared light source or a visible light source from the projector 156 or another not in 8B illuminated light source can be illuminated. The infrared light source or the visible light emitting light source can in this case on the scanner 20 attached or outside the scanner 20 be arranged. By determining the three-dimensional coordinates of the points of light 168 with the scanner and by using information about the geometry of the probe 152 can change the position of the probe tip 166 be determined, thereby determining the coordinates of the object surface 32 is possible. A probe used in this manner eliminates potential problems due to multipath interference and also allows relatively accurate measurement of holes, edges, and detailed features. The probe 166 In one embodiment, a probe that can be turned on by pressing an actuation button (not shown) on the probe, or the probe 166 can be a touch trigger probe that comes into contact with the surface 32 is turned on. In response to a signal generated by the operation button or the touch trigger probe, a communication circuit (not shown) transmits a signal to the scanner 20 , The points of light 168 are replaced in one embodiment by geometric light patterns that may include lines or curves.

Now referring to 9 , is there a method for acquiring coordinate data for points on the surface 32 of the object 34 using a fixed scanner 20 from 8A . 8B with a remote probe 152 shown. The procedure starts at block 170 with the scanning of the surface 32 of the object 34 , The procedure detects and determines in block 172 the three-dimensional coordinate data of the surface 32 , The method then determines in the query block 174 whether an anomaly in the coordinate data of the area 159 or there is a problem with the accuracy or resolution of the area 159 gives. An anomaly could be invalid data discarded due to, for example, multipath interference. Anomaly could also be missing data due to the reflectance of the surface or a poor resolution around a feature such as an opening or a hole. Details of a diagnostic method for detecting (identifying) a multipath disturbance and related problems are given by 12 specified.

Once the area 159 was identified, the scanner shows 20 in block 176 the operator that the coordinate data of the area 159 over the remote probe 152 can be detected. This area 159 can by emitting a visible light 157 to illuminate the area 159 are displayed. In one embodiment, the light 157 from the projector 156 emitted. The color of the light 157 can be changed to inform the operator about the nature of the anomaly or problem. For example, if a multipath fault occurs, the light can 157 be red in color, while it may be greenish at a low resolution. The area may also be displayed on a display device having a graphical representation (eg, a CAD model) of the object.

The procedure then goes to block 178 continue to take a picture of the remote probe 152 to pick up when the sensor 166 the surface 32 touched. The points of light 168 that may be LEDs or reflective targets, for example, are from one of the cameras 154 . 155 collected. Using best-fit methods, which are widely known to mathematicians, the scanner determines 20 in block 180 the three-dimensional coordinates of the center of the probe, from which three-dimensional coordinates of the surface of the object 32 in block 180 be determined. Once the points in the area 159 Where the anomaly has been detected, the procedure may be in block 182 with the scanning of the object 34 continue until the desired areas are scanned.

Now referring to 10 , is there another embodiment of the scanner 20 represented, which can be held in the hand during operation by the operator. The housing 22 can in this embodiment a handle 186 include holding the scanner to the operator 20 allowed during operation. The housing 22 includes a projector 188 and a camera 190 , which are arranged at an angle relative to each other that the light emitted by the projector 192 from the surface 32 reflected and from the camera 190 is caught. The scanner 20 from 10 is operated in a manner substantially similar to the embodiments of 1 and 3 is similar, and captures three-dimensional coordinate data of points on the surface by means of the principles of trigonometry 32 ,

The scanner 20 further comprises an integrated probe element 184 , The probe element 184 includes a sensor 194 at one end. The sensor 194 For example, a probe may be responsive to an operator pressing an actuation button (not shown) or may be a touch trigger probe responsive to contact with the surface 32 responds. As will be discussed in more detail below, the probe element allows 184 the operator the acquisition of the coordinates of points on the surface 32 by the sensor 194 the surface 32 touched.

The projector 188 , the camera 190 and an actuating circuit for the sensor 194 are electrically connected to a control device 50 coupled in the housing 22 is arranged. The control device 50 may include one or more microprocessors, digital signal processors, memory and signal conditioning circuits. The scanner 20 may further actuators (not shown) such as the handle 186 include, which can be manually turned on by the operator to the operation and the data acquisition by the scanner 20 to start. In one embodiment, the image processing for determining the x, y, z coordinate data becomes the surface 32 of the object 34 representing point cloud by the control device 50 carried out. The coordinate data may be local, such as in volatile or nonvolatile memory 54 get saved. The memory may be removable, such as a memory stick or a memory card. The scanner 20 has a communication circuit in other embodiments 52 that allows him to transfer the coordinate data to a remote processing system 56 transferred to. The communication medium 58 between the scanner 20 and the remote processing system 56 can be wired (for example, Ethernet) or wireless (for example, Bluetooth, IEEE 802.11). In one embodiment, the coordinate data is provided by the remote processing system 56 Detects and transmits the scanner 20 taken pictures via the communication medium 58 ,

Now referring to 11 , will the operation of the scanner 20 from 10 described. The procedure starts at block 196 with that the operator the surface 32 of the object 34 scans by holding the scanner 20 moved manually. The three-dimensional coordinates are in block 198 determined and recorded. In the request block 200 Determines if there is an anomaly in the coordinate data or if improved accuracy is needed. As discussed above, anomalies can occur for several reasons, such as multipath interference, surface reflectivity changes, or low feature resolution. If there is an anomaly, the procedure goes to block 202 continue where the operator the area 204 is shown. The area 204 can by projecting a visible light 192 with the projector 188 on the surface 32 are displayed. The light 192 In one embodiment, it is colored to notify the operator of the type of anomaly detected.

The operator then moves to block 206 to move the scanner from a first position to a second position (indicated by dashed lines). In the second position, the sensor touches 194 the surface 32 , The position and orientation (up to 6 degrees of freedom) of the scanner 20 in the second position can be determined using well-known best-fit method based on images taken by the camera 190 were recorded. Because the dimensions and the arrangement of the sensor 194 related to the mechanical structure of the scanner 20 are known, in block 208 the three-dimensional coordinate data of the points in the range 204 be determined. The procedure then goes to block 210 continue where the scanning of the object is continued. The scanning process continues until the desired area is scanned.

A general approach can be used to evaluate not only a multipath fault, but also the general quality that includes the resolution and effect of the type of material, surface finish, and geometry. Also referring to 12 , can a procedure 4600 in one embodiment, be performed automatically under the control of a computer. A step 4602 is to determine if information about three-dimensional coordinates of a test object is available. A first type of three-dimensional information is CAD data. CAD data usually indicates the nominal dimensions of a test object. A second type of three-dimensional information is measured three-dimensional data - for example, data previously with a Scanner or other device. The step 4602 may in some cases comprise a further step of aligning the reference system of the coordinate measuring machine - for example a laser tracker or scanner accessory with 6 degrees of freedom - to the reference system of the object. This is done in one embodiment by measuring at least three points on the surface of the object with the laser tracker.

If the answer to the in step 4602 Asked question is that the three-dimensional information is available, then in one step 4604 the computer or processor is used to calculate the susceptibility of the object measurement to multipath interference. In one embodiment, this is done by projecting each light beam emitted by the scanner projector and calculating the angle or reflection for each case. The computer or software identifies any area of the object surface that is prone to error due to multipath interference. In step 4604 it is also possible to carry out an analysis of the susceptibility to a multipath error at different positions of the 6-degree-of-freedom probe relative to the test object. In some cases, multipath interference may be avoided or minimized by selecting a suitable position and orientation of the 6-degree probe relative to the test object as described above. If the answer to the in step 4602 asked question is that the three-dimensional information is not available, then there is a step 4606 in measuring the three-dimensional coordinates of the object surface with any desired or preferred measurement method. Following the calculation of the multipath fault, a step 4608 be performed to evaluate other aspects of the expected sample quality. Such a quality factor is based on whether the resolution of the scan is sufficient for the characteristics of the test object. For example, if the resolution of a device is 3mm and there are sub-millimeter features for which valid scan data is desired, then those problem areas of the object should then be recorded for later corrective action. Another quality factor, which is partially related to resolution, is the ability to measure edges of the object and edges of holes. If the scanner performance is known, it can be determined whether the scanner resolution is good enough for certain edges. Another quality factor is the expected amount of light that returns from a particular feature. For example, it can be expected that little light (if any) will return from inside a small hole or from a glancing angle to the scanner. Little light can be expected from certain types and colors of materials. Certain types of material have a large penetration depth for the light of the scanner, and in this case, no good measurement results would be expected. In some cases, an automated program may request supplemental information from the user. For example, if a computer program steps 4604 and 4608 Based on CAD data, it may not know the type of material or surface characteristics of the object under test. In these cases, the step 4608 another step for obtaining material characteristics for the test object.

Following the analysis of the steps 4604 and 4608 is the step 4610 in deciding whether further diagnostic methods should be performed. A first example of a possible diagnostic method is the step 4612 for projecting a strip at a preferred angle to determine if a multipath disturbance is observed. The general indications of a multipath disturbance for a projected line strip were described above on the basis of 5 discussed. Another example of a diagnostic step is the step 4614 which is to project a collection of lines directed in the direction of epipolar lines onto the source light pattern, for example the source pattern of the light 30 of the projector 36 from 1 , In the case in which light lines in the source light pattern are aligned with the epilolary lines, these lines then also appear as straight lines in the image plane on the photosensitive arrangement. The use of epipolar lines is discussed in more detail in U.S. Patent Application Serial No. 13 / 443,946 filed April 11, 2012, assigned to the same assignee. If these patterns on the photosensitive array are not straight lines, or if the lines are out of focus or noisy, then a problem will be displayed, possibly as a result of a multipath disturbance.

The step 4616 is to select a combination of preferred measures based on the analyzes performed and the diagnostic methodology performed. If the speed is especially important during a measurement, you can take one step 4618 for measuring with a (structured) 2D pattern encoded light prefer. If greater accuracy is more important, then you can take a step 4620 for measuring with a (structured) 2D pattern coded light by means of successive patterns, so for example a sequence of sinusoidal patterns with varying phase and varying distance, prefer. If the procedure 4618 or 4620 should then be selected, then maybe a step 4628 It consists in repositioning the scanner, ie adjusting the position and orientation of the scanner to the position that minimizes multipath disturbances and directional reflections (glint) caused by the analysis in step 4604 were provided. Such displays may be provided to a user by illuminating problem areas with light from the scanner projector or displaying such areas on a monitor display. Alternatively, the next steps in the measurement process can be automatically selected by a computer or processor. Several options are available if the preferred scanner position does not eliminate multipath interference and glitter. The measurement can in some cases be repeated, repositioning the scanner and combining the valid measurement results. In other cases alternative measurement steps may be added to the procedure or performed instead of using structured light. As previously discussed, one step represents 4622 for scanning a light stripe, a convenient way to obtain information about an area is available, whereby there is less chance of a multipath disturbance problem occurring. A step 4624 moving a small spot of light over a region of interest also reduces the possibility of multipath interference problems. A step of measuring a portion of an object surface with a probe eliminates the possibility of multipath interference. A probe provides a known resolution based on the size of the probe tip and eliminates low reflectivity or large optical depth problems that might be encountered with some test objects.

In most cases, the quality may be in a combination of steps 4618 - 4628 collected data in one step 4630 based on the data obtained from the measurements in combination with the results of previous analyzes. When in one step 4632 the quality proves acceptable, the measurement becomes one step 4634 completed. Otherwise the analysis will be in step 4604 continued. In some cases, the 3D information may not be as accurate as desired. In this case, repeating some of the earlier steps might be helpful.

Although the invention has been described in detail in connection with only a limited number of embodiments, it will be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention may be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described, but consistent with the spirit and scope of the invention. While various embodiments of the invention have been described, it will be further understood that aspects of the invention may include only some of the described embodiments. The invention is therefore not to be considered as limited by the foregoing description and is limited only by the scope of the appended claims.

Claims (22)

Contactless optical three-dimensional measuring device comprising: an assembly comprising a first projector, a first camera, a second projector, and a second camera, wherein the first projector, the first camera, the second projector, and the second camera are fixed to each other, the first projector having a first light source, wherein the first projector is configured to emit on a surface of an object a first light having at least one pattern, the first camera having a first lens and a first photosensitive array, wherein the first camera is configured to form a first portion of the first reflected light of the surface and in response to generate a first signal, the first camera having a first field of view, wherein the first field of view is a first viewing angle range of the first camera, the second projector having a second light source, the second projector for is configured to have a second L on the surface of the object The second camera is configured to capture a second portion of the second light reflected from the surface and to responsively generate a second signal, wherein the second camera is non-emissive, the second camera having a second lens and a second photosensitive array a second field of view, the second field of view being a second field of view of the second camera, the second field of view being different from the first field of view; and a processor electrically coupled to the first projector, the second projector, the first camera, and the second camera executing computer executable program code that, when executed by the processor, performs computing operations that cause the first signal to be captured at a first projector first timing and detection of the second signal at a second time different from the first time, determining three-dimensional coordinates of a first point on the surface based at least in part on the first signal and determining three-dimensional coordinates of a second point on the surface based at least partially on the first second signal. The contactless optical three-dimensional measuring apparatus according to claim 1, wherein the second light is a light line along a direction perpendicular to one Direction of propagation of the second light direction is. The non-contact optical three-dimensional measuring device according to claim 1, wherein the at least one pattern comprises at least three non-collinear pattern elements. The contactless optical three-dimensional measuring device according to claim 3, wherein the second light comprises a second pattern, the second pattern having at least three non-collinear pattern elements. The contactless optical three-dimensional measuring apparatus according to claim 2, wherein the light line is a line pattern which is reciprocated with time. The contactless optical three-dimensional measuring apparatus according to claim 2, wherein the light line is a light spot which is reciprocated with time. The contactless optical three-dimensional measuring device according to claim 1, wherein the first field of view is at least twice as large as the second field of view. The non-contact optical three-dimensional measuring device according to claim 1, wherein the first photosensitive array comprises a first pixel, the first pixel being configured to detect a light reflected from a first area of the surface, the second photosensitive array comprising a second pixel second pixel is configured to detect a light reflected from a second region of the surface, the second region being smaller than the first region. A method of determining three-dimensional coordinates on a surface of an object, the method comprising: Providing an assembly comprising a first projector, a first camera, a second projector, and a second camera, wherein the first projector, the first camera, the second projector, and the second camera are stationary with a first distance between the first projector and the first camera, wherein there is a second distance between the second projector and the second camera, the first projector having a first light source, wherein the first projector is configured to emit on the surface a first light having at least one pattern, wherein the first camera has a first lens and a first photosensitive array, wherein the first camera is configured to capture a first portion of the first light reflected from the surface, the first camera having a first field of view, the first field of view a first viewing angle range the first camera is, with the second projector on e second light source, wherein the second projector is configured to emit a second light on the surface, the second camera having a second lens and a second photosensitive array, the second camera configured to control a second portion of the one of Surface of reflected second light, the second camera having a second field of view, the second field of view being a second field of view of the second camera, the second field of view being different from the first field of view; Providing a processor electrically coupled to the first projector, the first camera, the second projector, and the second camera; Emitting the first light having the at least one pattern in a first process from the first projector onto the surface; Taking a first image of the surface with the first camera in the first process and in response sending a first signal to the processor; Determining a first set of three-dimensional coordinates of first points on the surface, the first set based at least in part on the at least one pattern, the first signal, and the first distance; Performing a diagnostic method that determines a quality score for the first sentence; Emitting the second light in a second process from the second projector onto the surface; Taking a second image of the surface with the second camera in the second process and in response sending a second signal to the processor; and Determining a second set of three-dimensional coordinates of second points on the surface, the second set based at least in part on the second light, the second signal, and the second distance. The method of claim 9, wherein the step of emitting the second light in a second process from the second projector comprises a preceding step of moving the assembly from a first position to a second position. The method of claim 10, wherein the step of moving the assembly comprises instructing the operator to move the assembly to the second position by turning on indicator lights on the assembly. The method of claim 10, wherein the step of moving the assembly includes projecting a light onto the object to indicate a direction of movement to the second position. The method of claim 11, wherein the step of moving the assembly comprises displaying a portion of the object to be scanned in a graphical representation on a display device. The method of claim 9, wherein the step of performing a diagnostic method that determines a quality factor for the first set comprises the quality factor based at least in part on a multipath fault being present. The method of claim 14, wherein the step of performing a diagnostic method that determines a quality factor for the first set comprises: Providing a computer-aided drawing model (CAD model) of the object to be measured; Checking, based on the CAD model, the presence of multipath interference by detecting that light rays of the first projector are reflected from a first surface point of the object to a second surface point of the object, the second surface point being a point pictorially captured by the first camera; and Determining the quality factor based at least in part on the presence of a multipath fault. The method of claim 15, wherein in the step of emitting the second light in a second process from the second projector to the surface, the second light is in the form of a line or a dot. The method of claim 16, wherein in the step of emitting a second light in the second process, the second light is in the form of a line that is reciprocated with time or a point that is reciprocated with time, wherein the light line is along a direction perpendicular to a direction of propagation of the second light. Method according to claim 14: further comprising a step of obtaining a plurality of three-dimensional coordinates of the surface of the object by scanning at least a portion of the surface; and in the step of performing the diagnostic method, further comprising checking, based on the obtained plurality of three-dimensional coordinates, the presence of multipath interference by detecting that light rays of the first projector are reflected from a first surface point of the object to a second surface point of the object second surface point is a point pictorially captured by the first camera, and determining the quality factor based at least in part on the presence of the multipath interference. The method of claim 18, wherein in the step of emitting the second light in a second process from the second projector onto the surface, the second light is in the form of a line or a dot, the line being along a direction perpendicular to a direction of propagation of the second Light extending direction is present. The method of claim 19, wherein in the step of emitting the second light in the second process from the second projector to the surface, the line or point is reciprocated over time. The method of claim 9, wherein the step of determining a quality factor for the first sentence comprises: Determining a resolution of the first set of three-dimensional coordinates; and Determining the quality factor further based at least in part on the resolution. The method of claim 9, wherein the at least one pattern is a time-varying pattern.

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