DE102014110995A1 - Registration of a clustered scene with scan request - Google Patents

Registration of a clustered scene with scan request

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Publication number
DE102014110995A1
DE102014110995A1 DE102014110995.3A DE102014110995A DE102014110995A1 DE 102014110995 A1 DE102014110995 A1 DE 102014110995A1 DE 102014110995 A DE102014110995 A DE 102014110995A DE 102014110995 A1 DE102014110995 A1 DE 102014110995A1
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DE
Germany
Prior art keywords
scan
scans
intersection
laser scanner
method according
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Withdrawn
Application number
DE102014110995.3A
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German (de)
Inventor
Sebastian Bartmann
Helmut Kramer
Daniel Pompe
Michael Schanz
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Faro Technologies Inc
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Faro Technologies Inc
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Priority to DE102014110995.3A priority Critical patent/DE102014110995A1/en
Publication of DE102014110995A1 publication Critical patent/DE102014110995A1/en
Application status is Withdrawn legal-status Critical

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06Systems determining position data of a target
    • G01S17/42Simultaneous measurement of distance and other co-ordinates
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/86Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/88Lidar systems specially adapted for specific applications
    • G01S17/89Lidar systems specially adapted for specific applications for mapping or imaging
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481Constructional features, e.g. arrangements of optical elements
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06Systems determining position data of a target
    • G01S17/08Systems determining position data of a target for measuring distance only
    • G01S17/32Systems determining position data of a target for measuring distance only using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
    • G01S17/36Systems determining position data of a target for measuring distance only using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves with phase comparison between the received signal and the contemporaneously transmitted signal
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06Systems determining position data of a target
    • G01S17/46Indirect determination of position data
    • G01S17/48Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves

Abstract

In a method for optically scanning and measuring a scene by means of a laser scanner (10), in which a plurality of scans ({X (i)}) are generated in order to be subsequently registered in a common coordinate system (XYZ) of the scene, at least a cluster (Gm) from at least one scan ({X (i)}) generates (102), further scans ({X (j)}) in the coordinate system of the cluster (Gm) first registered (103) and the registration then confirmed (105), when certain quality criteria are met, wherein the further scans ({X (j)}, {X (i + 1)}) are generated in response to data (ΔC) of a location tracking device (80).

Description

  • The invention relates to a method having the features of the preamble of claim 1.
  • In the DE 10 2009 015 922 A1 a method of this kind is described in which a scene with multiple scans is detected. For this purpose, the laser scanner is moved to a new location after a scan in order to generate another scan. The generated scans are registered with their measuring points in a common coordinate system, the totality of the measuring points forming a three-dimensional point cloud.
  • The invention is based on the object to improve a method of the type mentioned. This object is achieved by a method with the features of claim 1. Advantageous embodiments are the subject of the dependent claims.
  • By means of the known method for registering multiple scans of a scene, the registration based on the pairwise check of two scans should theoretically be unique and therefore completely automatic. In practice, however, not all scans are tested in pairs for performance reasons, but only within a neighborhood, which results, for example, from the history of the capture of the scene. Therefore, interruptions to the registration may occur.
  • According to the invention, at least one cluster is first generated from at least one scan to which further scans are added as long as certain quality criteria are met. Otherwise, a new cluster is created. If more than one cluster exists after auto-clustering, the clusters must be joined together. For this, clusters and / or scans are to be selected in pairs and registered as a test. For support, data from a location tracking device may be used that tracks movement of the laser scanner between locations within the scene.
  • With post registration, these data may help the tracking device to select the pairs of scans, in the case of onsite registration, the evaluation of the data may request the next (or additional) scan trigger. In all cases, confirmations of the user can be obtained after the (proposed) assembly of clusters.
  • In the following the invention with reference to an embodiment shown in the drawing with modifications is explained in detail. Show it
  • 1 a schematic flow diagram of the automatic generation of the clusters,
  • 2 a schematic representation of clusters,
  • 3 12 is a schematic flow diagram of clustering using data from a location tracking device;
  • 4 a schematic flow diagram of the assembly of the clusters with generation of further scans in dependence on data of a tracking device,
  • 5 a schematic, partially sectioned view of a laser scanner in operation, and
  • 6 a perspective view of a laser scanner.
  • The present invention relates to a 3D coordinate measuring device which directs a light beam onto an object O which is either a (cooperative) target, for example a retro-reflector, or a non-cooperative target, for example a diffusely scattering surface of the object O, can be. A distance meter in the device measures a distance to the object O, and rotary encoders measure the rotation angles of two axes in the device. The measured distance and the two angles allow a processor in the device to determine the 3D coordinates of the object O. In the present case, such a device becomes the case of a laser scanner 10 treated, but the extension to a laser tracker or a total station is obvious to the expert.
  • Laser scanners are typically used to detect closed or open spaces, such as building interiors, industrial facilities and tunnels. Laser scanners are used for many purposes including Building Information Modeling (BIM), industrial analysis, accident reconstruction applications, archaeological surveys and forensic investigations. A laser scanner can be used to optically detect and measure objects in the laser scanner environment by capturing data points that represent objects within the environment. Such data points are obtained by directing a light beam at the objects and collecting the reflected or scattered light by the distance, two angles (ie, an azimuth angle and a zenith angle), and optionally a gray tone value to investigate. This raw scan data is collected, stored and sent to one or more computers to generate a three-dimensional image representing the captured area or object. To generate the image, at least three values are collected for each data point. These three values may include the distance and two angles, or may be converted values such as x, y, z coordinates.
  • The drawing shows a laser scanner 10 for optically scanning and measuring the surroundings of the laser scanner 10 , The laser scanner 10 has a measuring head 12 and a foot 14 on. The measuring head 12 is so on the foot 14 mounted that the measuring head 12 around a first axis 12a relative to the foot 14 is rotatable, driven by a first rotary drive. The rotation about the first axis 12a can be around the middle of the foot 14 respectively. The measuring head 12 has a mirror 16 on which is a second axis 16a can rotate, powered by a second rotary actuator. Relative to a normal, upright position of the laser scanner 10 , may be the first axis 12a be referred to as a vertical axis or azimuth axis, and the second axis 16a can be referred to as a horizontal axis or zenith axis. The laser scanner 10 may have a gimbal point or center C 10 , which is the intersection of the first axis 12a and the second axis 16a is.
  • The measuring head 12 further comprises a transmitter for electromagnetic radiation, for example a light emitter 17 on, which has a transmission beam 18 sending out. In the preferred embodiment, the transmitted light beam is 18 a coherent light such as a laser beam. The laser beam may have a wavelength in the range of about 300 to 1600 nm, for example 790 nm, 905 nm, 1550 nm, or less than 400 nm. In principle, however, other electromagnetic waves with a larger or smaller wavelength can be used. The transmitted light beam 18 may be amplitude modulated or intensity modulated, for example with a sinusoidal or rectangular waveform. Alternatively, the transmitted light beam 18 be otherwise modulated, for example, by a chirp signal, or coherent reception methods can be used. The transmitted light beam 18 is from the light emitter 17 on the mirror 16 given, deflected there and in the surroundings of the laser scanner 10 sent.
  • A reflected light beam, subsequently as a received light beam 20 is reflected by an object O in the environment. The reflected or scattered light is from the mirror 16 captured and onto a light receiver 24 redirected with a receiving optics. The directions of the transmitted light beam 18 and the receiving light beam 20 arise from the angular positions of the measuring head 12 and the mirror 16 around the axis 12a respectively. 16a , These angular positions in turn depend on their respective rotary actuators. The angle of rotation about the first axis 12a is detected by a first rotary encoder. The angle of rotation about the second axis 16a is detected by a second rotary encoder.
  • A control and evaluation device 22 stands with the light transmitter 17 and the light receiver 21 in the measuring head 12 in data connection, with parts of the control and evaluation device 22 also outside the measuring head 12 can be arranged, for example as a foot 14 connected computer. The control and evaluation device 22 is designed for a large number of measuring points X a corresponding number of distances d between the laser scanner 10 and the measurement points X on the object O to determine. The distance to a certain measuring point X is at least partially determined by the running speed of the light in the air through which the electromagnetic radiation propagates from the device to the measuring point X. In the preferred embodiment, the phase shift is in the modulated light beam 18 . 20 which is sent to and received from the measurement point X is determined and evaluated to obtain a measured distance d.
  • The speed of light in air depends on air properties such as air temperature, air pressure, relative humidity and carbon dioxide concentration. These air properties affect the refractive index of the air. The speed of light in air is the speed of light in vacuum divided by the refractive index. A laser scanner of the type described herein is based on the light transit time in the air (the transit time the light takes to travel from the device to the object and back to the device). A method of distance measurement based on the time of flight of light (or the duration of another type of electromagnetic radiation) depends on the speed of light in air and is therefore easily distinguished from triangulation distance measuring methods. In triangulation-based methods, light is emitted from its light source in a particular direction and then captured on a camera pixel in a particular direction. By knowing the distance between the camera and the projector and matching a projected angle with a reception angle, the triangulation method allows the determination of the distance to the object based on a known length and two known angles of a triangle. The triangulation method therefore does not depend directly on the speed of light in air.
  • The measuring head 12 can be a display device 24 include that in the laser scanner 10 is integrated. To the display device 24 includes a user interface, which may be a graphical touch screen as shown in the drawing. For example, the display device 24 Have a user interface that allows the operator to the laser scanner 10 To give measuring instructions, in particular to set the parameters or the operation of the laser scanner 10 to start, and the display device 24 can also display measurement results.
  • In one embodiment, detecting the environment around the laser scanner 10 by means of a fast rotation of the mirror 16 around the second axis 16a instead, while the measuring head 12 slowly around the first axis 12a rotates, wherein the assembly moves in a spiral. In an exemplary embodiment, the rotor mirror rotates at a maximum speed of 5820 RPM. A scan is defined as the totality of the measurement points X of such a measurement. For such a scan, the center C 10 defines the origin of the local stationary frame of reference. The foot rests in this local stationary frame of reference 14 ,
  • In addition to the distance d from the center C 10 to a measuring point X, the laser scanner 10 still detect a gray level value with respect to the received optical power. The greyscale value can be achieved, for example, by integrating the bandpass-filtered and amplified signal in the light receiver 21 be determined via a measuring period X associated measurement period. Optionally, by means of a color camera 25 Color images are generated. By means of these color images, it is also possible to assign colors (R, G, B) to the measuring points X as additional values.
  • In order to capture a scene from different directions or an extended space, multiple scans are generated from different locations (corresponding to a set of different centers) and then registered in a common coordinate system XYZ of the scene. The laser scanner 10 it has to change its location, which then each center C 10 of the laser scanner 10 within the common coordinate system XYZ is moved to a new center of said set.
  • To register the scans, point-based methods or methods with targets can be used. Both methods use data in overlapping areas of the scans. By way of example, targets should be registered in the present exemplary embodiment. The targets are located and identified in the overlapping areas of the scans. Targets are both "natural" targets, ie specific formations of the object O, as well as "artificial" targets, ie targets specially mounted for the scanning process on the object O or in the environment, for example checkerboard patterns. Preferably, as in the DE 10 2009 015 922 A1 for each target determines the geometry in which it is embedded and which is defined by the neighboring targets. The embedding geometries can then be compared with each other to first find pairs of correspondence of the targets and then automatically find the best possible assignment of the two scans. If all scans are registered in the common coordinate system XYZ of the scene, the totality of all measurement points X of all scans forms a three-dimensional point cloud 3DP.
  • Normally it is possible to register all scans by means of the targets (or the data for the point-based methods), even without additional information about the relative positions of the centers of the scans. To improve performance, the timestamp of the scans can be used to find and register neighboring scans faster. The result of the registration may be by means of the display device 24 being represented. A confirmation from the user is optional.
  • However, there may also be registration issues, such as too few targets in overlapping areas of the scans, ambiguous embedding geometries, or a difficult topology. It may also be that the problems are present, but not immediately recognized, but only by the user. Preferably, therefore, automatically clusters are generated, each consisting of uniquely related scans. For the definition of this clear togetherness certain quality criteria can be specified, which must be met. Such a quality criterion can be, for example, a threshold value for the remaining distance squares of the targets after the assignment of the embedding geometries, wherein the quality criterion should increase with increasing agreement.
  • According to the invention, the laser scanner 10 a location tracking device 80 on, connected to the control and evaluation device 22 connected. The location tracking device 80 is least during the change between different locations, for example C (i) and C (j) , of the laser scanner 10 active and recognizes this relocation. In particular, it measures the vectorial relative position ΔC of a new location C (j) relative to the previous location C (i) . There are various hardware implications for the location tracking device 80 possible.
  • The location tracking device 80 may, for example, belong to the group of the Hodometer. It is preferred that the laser scanner 10 mounted on a trolley, such as in the DE 10 2010 033 561 B3 is described. The trolley has at least two wheels, preferably on the same axis, in each case an encoder, which measures the angle of rotation of the associated wheel. From the two measurement data series, the two-dimensional (relative) movement of the laser scanner 10 be determined. The location tracking device 80 may also have an altimeter and / or inclinometer. In combination with the measurement data series of the encoders or other data from the hodometer, the three-dimensional (relative) movement of the laser scanner can be determined 10 be determined. Furthermore, the location tracking device 80 have a compass which provides comparison data for correcting the odometer data or alternatively replaces the odometer. The location tracking device 80 For example, it can detect its movement relative to a reference surface by detecting the optical flux, as shown in FIG DE 10 2009 035 336 B3 is described.
  • The location tracking device 80 For example, it can be designed as an inertial measurement unit. This measures their possible angular velocities and accelerations in the three different spatial directions, for which they have three mutually orthogonal gyroscopes (rotation rate sensors) and three mutually orthogonal Accelerometer (acceleration sensors). From the measurement data series, the three-dimensional (relative) movement of the laser scanner can (by integration) 10 be determined.
  • The location tracking device 80 can be designed, for example, as a GPS unit. As far as a free satellite reception exists, the absolute movement of the laser scanner 10 be determined. In modifications, the GPS unit is combined with an "indoor positioning system" and / or with a hodometer and / or altimeter and / or inclinometer.
  • The laser scanner 10 can also be mounted on an autonomously moving robot, as in the DE 10 2012 109 481 A1 is described. The location tracking device 80 , For example, the above-mentioned inertial measuring unit, then in the laser scanner 10 or alternatively be arranged in the robot.
  • As a rule, the possible error is in the determination of the three-dimensional movement of the laser scanner 10 large, for example, the altimeter in the order of a floor. Even with an inertial measurement unit, the error can accumulate in a considerable way. Therefore, an attempt is first made to register the scans by means of the dot-based methods or the methods with targets.
  • In 1 shows a schematic representation of the procedure for "auto-clustering", as it can be carried out for example by means of a suitable filter device. After a start step 101 is in a processing step 102 defines a first cluster G 1 and assigns the first scan {X (1) } as the first single scan (indicated by an arrow). This first scan {X (1) } also defines the coordinate system of the first cluster G 1 . For a subsequent loop, which processes a cluster G m on each pass, m = 1 on the first pass. The further scans {X (i) } start with i = 2.
  • It starts the said loop, which is a processing step 103 contains, in which another scan {X (i) } in the coordinate system of the (currently processed) cluster G m is registered as a test. For reasons of performance, in particular because the cluster G m can contain a large number of targets, a pair is preferably formed from the last successfully registered scan and the further scan {X (i) }, which is registered as a test. In a decision step 104 It is checked whether the test-by-registration was successful, ie the quality criteria for a registration are fulfilled. If this is the case (Y), then in a processing step 105 the registration is confirmed, otherwise (N) the trial registration is discarded.
  • In a subsequent decision step 106 It checks if there are any more scans {X (i) } that have not yet been tested in this loop ("free scans"). This check will normally be done using a count-up loop counter (preferably the number "i" of the scan) and appropriate flags. If there are still such free scans {X (i) } (Y), the loop jumps back to the processing step 103 with the test registration. The decision step 106 could also be done at the beginning of the loop. If there are no free scans {X (i) } left (N), the "auto-clustering" ends with an end step 107 ,
  • Will the trial registration after the decision step 104 discarded, so is in a processing step 108 defines a new cluster G m (with m = m + 1) and assigns the last vain test scan {X (i) } to this new cluster G m . This latter scan {X (i) } defines the coordinate system of the new cluster G m . The method then becomes the processing step 103 the trial registration continued.
  • In a modification to this is in an unsuccessful test registration not immediately new cluster started, but for the currently edited cluster G m a certain number of the next free scans {X (i) } tested. It is sensible in terms of performance to limit the number of scans still to be tested by defining a bound, for example based on the timestamp or the sequential number of scans, ie a spatial and / or temporal bound, so that only an attempt is made to temporarily register neighboring scans in time (and therefore also spatially) as a rule. This reduces the complexity of the registry.
  • As an alternative to the described serial method, in a rather parallel process (corresponding to the crystal growth), the scans {X (i) } can be tested in pairs for a test-by-registration. From the belonging pairs a cluster G m is formed in each case (as a crystallization seed). From the clusters G m or preferably from individual scans from the clusters G m on the one hand and the free scans {X (i) } on the other hand, new pairs arise, which are checked again for a test-by-registration until finally no further registration is successful.
  • In the case of a building, the clusters G m often consist of adjacent scans {X (i) } of the same room, the same floor, the same building or the interior and exterior.
  • There remains the problem of merging the clusters G m , for example by means of a suitable registration device. To do this, the data of the location tracking device 80 used. The joining of the clusters G m can be visualized, for example to indicate the progress. There are several possible methods, the cluster G m , using the data of the location tracking device 80 put together. Such from the location tracking device 80 The data supplied are preferably the relative positions ΔC (or absolute positions) of the locations C (i) of the laser scanner 10 which are at the same time the centers of already created or imagined (or planned) scans {X (i) }.
  • In order to compare such a relative position ΔC with the size of a scan {X (i) }, preferably the scan {X (i) } will be described approximately by means of a characteristic shape, for example a circle, a sphere, a square or a cube. Furthermore, the characteristic shape is assigned a characteristic length L (c) which describes the size of the characteristic shape and thus also describes the size of a scan {X (i) }, for example the diameter of the circle / sphere or the edge length of the square / Cube or one dimension. The characteristic length L (c) may depend on the range of the laser scanner 10 and depend on properties of the scene, for example resulting from the standard deviation of the measurement points X (i) of a scan {X (i) } from its center C (i) or from another statistical value. The characteristic shape is arranged around a location or a center C (i) of the scan {X (i) }, respectively, and the characteristic length L (c) is preferably the same for all scans {X (i) }. Optionally, the characteristic length L (c) is changed during the process, for example if can not be put together all clusters G m. The performance increases if, for comparisons with the relative position ΔC, instead of the scans {X (i) } with all their measuring points X (i), first only the characteristic shape with the characteristic length L (c) assigned to it is used.
  • From the idea of the characteristic length L (c) follows the intersection Q (ij) of two already generated scans {X (i) }, {X (j) } or a generated scan {X (i) } with an imaginary scan on one Location C (j) . For this purpose, the intersection Q (ij) is first defined as the overlap of the two characteristic forms around the respective centers C (i) , C (j) . The size of the intersection Q (ij) preferably relates to the number of measurement points X (i) , X (j) and / or targets contained in the intersection Q (ij) , which are counted accordingly (in the variant with the imaginary scan can only be counted in the generated scan). Optionally, the size of the intersection Q refers (ij) but purely on the area of the intersection Q (ij), which ultimately from the relative position .DELTA.C and the characteristic length L (c) is determined. In a simplified third definition of the size of the intersection Q (ij) , the intersection Q (ij) is determined one-dimensionally, in particular as the difference between the characteristic length L (c) and the magnitude of the relative position ΔC. There are further definitions possible.
  • The intersection Q (ij) can be compared with a predetermined threshold Q (c) , which depends on the characteristic length L (c) and optionally further statistical values of the scans {X (i) }. For example, in the second definition with the area, the threshold Q (c) = L (c) * L (c) / 10 may be, for example, Q (c) = L (c) / 5 in the third definition with the one-dimensional intersection , Here too further definitions and additional modifications are possible.
  • A first procedure ("post registration"), which takes place after the creation of all scans {X (i) }, is shown as a flowchart in FIG 3 shown. After a start step 121 be in one processing step 122 two clusters, and preferably one scan each, are selected from each of the two clusters, which together comprise a pair for a trial Create registration. More specifically, a scanning {X (i)} is selected for example from a first cluster G k, in the coordinate system a second cluster G l is to be tested as registered, for which, in turn, representative of this second cluster G l a scan {X (j) } is selected, and the two scans {X (i) }, {X (j) } form the said pair. From the data of the location tracking device 80 For the two scans {X (i) }, {X (j) }, at least the approximate relative position ΔC results, in which their respective centers C (i) , C (j) are relative to one another.
  • In a processing step 123 At least approximately, the overlapping area of the two scans {X (i) }, {X (j) } is determined, ie the intersection Q (ij) of the two scans {X (i) }, {X (j) } is formed and their size determined according to one of the above definitions. In a decision step 124 it is checked whether the said intersection Q (ij) is sufficiently large compared to the predetermined threshold Q (c) . If the intersection Q (ij) is not sufficiently large (N), ie, in particular if it falls below the threshold value Q (c) , the selection of the pair of scans {X (i) }, {X (j) } is discarded Method jumps back to the processing step 122 , However, if the intersection Q (ij) is sufficiently large (Y), then in one processing step 125 tried the couple - similar to the processing step 103 - register as a test and thus join the clusters together. In a decision step 126 it is checked if this joining was successful. If this is the case (Y), then takes place in the processing step 127 a confirmation of the registration (according to the processing step 105 ). Otherwise (N) the two clusters remain separated. In another decision step 128 (which can also be arranged elsewhere in the loop) is checked whether there are still clusters G m that are not yet joined, so are still "free". If this is the case (Y), the loop becomes the processing step 122 continued. Otherwise (N), all clusters G m are joined together, so that with one final step 129 can be completed.
  • Further possible methods exist in the case of on-site registration, that is, between the generation of the scans {X (i) }.
  • According to a second method, during the change of the location of the laser scanner 10 starting with a starting step 121 , is in a processing step 122 from the data of the location tracking device 80 More specifically, the approximate relative position ΔC of the current location C (i + 1) to the center C (i) of the last generated scan {X (i) }, the generation of a scan {X (i) } with the center at the current location C (i + 1) . Starting from said relative position .DELTA.C and the characteristic length L (c) is in the processing step 123 the overlapping area between the last generated scan {X (i) } and the intended scan {X (i + 1) } is estimated, ie an imaginary intersection Q (i, i + 1) between the last generated scan {X (i) } and the intended scan {X (i + 1) }.
  • In a decision step 124 it is checked whether the said intersection Q (i, i + 1) is sufficiently large compared to the predetermined threshold value Q (c) . If the intersection Q (i, i + 1) is sufficiently large (Y), the intended generation is discarded and the process returns to the processing step 122 , Otherwise (N), ie if the intersection Q (i, i + 1) does not appear to be so large, in particular the threshold Q (c) falls below, is in an output step 131 the next scan {X (i + 1)} requested, whereupon the final step 129 follows. The request may be directed to the user. Especially in the case of mounting the laser scanner 10 On an autonomously moving robot, the request may also cause the robot to stop and automatically trigger the scan.
  • The method described becomes again only after the generation of this next scan {X (i + 1) }, its test-wise registration in the current cluster G m (method step 103 ) and the confirmation of registration (procedural step 105 ) go through again. Ideally, no auto-clustering is necessary, since all scans {X (i) } are registered in the same cluster G m . If the scene nevertheless decays into clusters G k , G l , these are joined together according to the first method after the creation of all scans {X (i) }.
  • According to a third method, after the generation of each scan {X (i) }, it is attempted to register this (test-wise), ie to add it to the previous cluster G l . Preferably, the (trial) registration is between two scans when the color camera 25 is used. Optionally, the laser scanner allows 10 the next (ordinary) scan {X (i) } only if a registration of the previous scans was successful.
  • If the existing cluster G l ended and a new cluster G k be started (have to), ie if the test as registration was unsuccessful, an additional (extraordinary) Scan {X (j)} is the user at least requested, sensibly in the last recorded Area from which the cluster G l just ended and the newly started cluster G k (ie the unsuccessfully joined clusters) originate, and which can also be displayed to the user in a timely manner. The later the request for the additional scan {X (j) }, the harder it is for the user to do the find the right area with the unsuccessfully assembled clusters G l , G k .
  • From the additional scan {X (j) } and selected existing scans {X (i) } of the just ended cluster G l , the pairs are formed. If the completed cluster G l was successfully completed by the additional scan, an attempt is made to merge the terminated cluster G l and the newly started cluster G k . If necessary, there is another request for an additional scan.
  • The second method and the third method can be combined with each other, ie if in the second method the intersection Q (i, i + 1) - contrary to expectations - was clearly too small, an additional scan can be requested.
  • LIST OF REFERENCE NUMBERS
  • 10
     laser scanner
    12
     probe
    14
     foot
    16
     mirror
    17
     light source
    18
     Transmitted light beam
    20
     Reception light beam
    21
     light receiver
    22
     Control and evaluation device
    24
     display device
    25
     color camera
    80
     Location tracking device
    101
     Starting step (cluster formation)
    102
     Processing step (assign first scan to first cluster)
    103
     Processing step (trial by trial registration)
    104
     Decision step (test-by-registration successful)
    105
     Processing step (confirmation of registration)
    106
     Decision step (untested scans)
    107
     Final step (cluster formation)
    107
     Decision step (free scans)
    108
     Processing step (new cluster)
    121
     Starting step (cluster joining)
    122
     Processing step (selection of clusters, scans)
    123
     Processing step (determination of intersection)
    124
     Decision step (cut quantity sufficient)
    125
     Processing step (trial by trial registration)
    126
     Decision step (successful)
    127
     Processing step (confirmation of registration)
    128
     Decision step (free clusters)
    129
     End step (cluster joining)
    3DP
     point cloud
    C 10
     Center of the laser scanner
    C (i) , C (i + 1) , C (j)
     Locations of the laser scanner, centers of scans
    .DELTA.C
     relative position
    d
     distance
    G l , G k , G m
     cluster
    L (c)
     characteristic length
    O
     object
    Q (ij)
    Intersection (of the scans {X (i) }, {X (j) })
    Q (c)
     Threshold (for the intersection)
    {X (i) }, {X (j) }
     scan
    X
     measuring point
    XYZ
     coordinate system
  • QUOTES INCLUDE IN THE DESCRIPTION
  • This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.
  • Cited patent literature
    • DE 102009015922 A1 [0002, 0025]
    • DE 102010033561 B3 [0029]
    • DE 102009035336 B3 [0029]
    • DE 102012109481 A1 [0032]

Claims (10)

  1. Method for optically scanning and measuring a scene by means of a laser scanner ( 10 ), in which a plurality of scans ({X (i) }) are generated in order to be subsequently registered in a common coordinate system (XYZ) of the scene, characterized in that first at least one cluster (G m , G k , G l ) is generated from at least one scan ({X (i) }) ( 102 ), further scans ({X (j) }, {X (i + 1) }) in the coordinate system of the cluster (G m , G k , G l ) are first registered as a test ( 103 ) and then the registration is confirmed ( 105 ), if certain quality criteria are met, the further scans ({X (j) }, {X (i + 1) }) being dependent on data (ΔC) of a location tracking device ( 80 ) be generated.
  2. Method according to claim 1, characterized in that starting from the last generated scan ({X (i) }) a further scan ({X (j) }, {X (i + 1) }) is first considered ( 122 ) and then depending on the data (ΔC) of the location tracking device ( 80 ) is generated at the current location (C (i + 1) ).
  3. Method according to Claim 2, characterized in that the last scan ({X (i) }) and the intended scan ({X (i + 1) }) each have a center (C (i) , C (i + 1) ), wherein the centers (C (i) , C (i + 1) ) are in a relative position (.DELTA.C) to each other, which of the location tracking device ( 80 ) is delivered.
  4. Method according to claim 2 or 3, characterized in that an intersection (Q (ij) ) of the last generated scan ({X (i) }) and the intended scan ({X (i + 1) }) are formed ( 123 ) and compared with a threshold (Q (c) ) ( 124 ).
  5. Method according to Claim 4, characterized in that the size of the intersection (Q (ij) ) is determined from the number of measurement points (X (i) ) contained in the intersection (Q (ij ) ) and / or targets, or in that Size of the intersection (Q (ij) ) is determined from the area of the intersection (Q (ij) ), or the size of the intersection (Q (ij) ) is determined one-dimensionally.
  6. Method according to Claim 5, characterized in that the generation of the intended scan ({X (i + 1) }) is requested ( 131 ), if the size of the intersection (Q (ij) ) falls below the threshold value (Q (c) ) ( 124 ).
  7. Method according to one of the preceding claims, characterized in that the size of the scans ({X (i) }, {X (i + 1) }) is described by means of a characteristic length (L (c) ) and / or that the scans ({X (i) }, {X (i + 1) }) by means of a characteristic form
  8. Method according to one of the preceding claims, characterized in that each scan ({X (i) }) after its generation and before the generation of the next scan ({X (i + 1) }) in the coordinate system of the cluster (G m ) on a test basis is registered.
  9. Method according to one of the preceding claims, characterized in that the test registrations are made automatically using data in overlapping areas of the scans ({X (i) }, scans ({X (j) }).
  10. Laser scanner ( 10 ) for carrying out a method according to one of claims 1 to 9, comprising a foot ( 14 ) and one relative to the foot ( 14 ) rotatable measuring head ( 12 ) with a light transmitter ( 17 ), which transmits a transmitted light beam ( 18 ), a light receiver ( 21 ), one of an object (O) in the vicinity of the laser scanner ( 10 ) reflected or otherwise scattered received light beam ( 20 ), and a control and evaluation device ( 22 (), Which for a plurality of measurement points (X) of each scan ({X (1)}, {X (2)}) each have at least the distance (d) from the center (C 10) of the laser scanner 10 ) to the object (O) and registers the generated scans ({X (1) }, {X (2) }) in a common coordinate system (XYZ) of the scene, the center (C 10 ) of the laser scanner ( 10 ) during creation of a scan ({X (i) }, {X (j) }) and is movable between scans ({X (i) }, {X (j) }).
DE102014110995.3A 2014-08-01 2014-08-01 Registration of a clustered scene with scan request Withdrawn DE102014110995A1 (en)

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Application Number Priority Date Filing Date Title
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009015922A1 (en) 2009-03-25 2010-10-07 Faro Technologies, Inc., Lake Mary Method for optically scanning and measuring a scene
DE102009035336B3 (en) 2009-07-22 2010-11-18 Faro Technologies, Inc., Lake Mary Device for optical scanning and measuring of environment, has optical measuring device for collection of ways as ensemble between different centers returning from laser scanner
DE202010013825U1 (en) * 2010-10-04 2011-02-17 V&R Vision & Robotics Gmbh Portable 3D measuring device
DE102010033561B3 (en) 2010-07-29 2011-12-15 Faro Technologies, Inc. Device for optically scanning and measuring an environment
EP2682783A1 (en) * 2012-07-03 2014-01-08 Zoller & Fröhlich GmbH Method and device for evaluating laser scans
DE102012109481A1 (en) 2012-10-05 2014-04-10 Faro Technologies, Inc. Device for optically scanning and measuring an environment

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009015922A1 (en) 2009-03-25 2010-10-07 Faro Technologies, Inc., Lake Mary Method for optically scanning and measuring a scene
DE102009035336B3 (en) 2009-07-22 2010-11-18 Faro Technologies, Inc., Lake Mary Device for optical scanning and measuring of environment, has optical measuring device for collection of ways as ensemble between different centers returning from laser scanner
DE102010033561B3 (en) 2010-07-29 2011-12-15 Faro Technologies, Inc. Device for optically scanning and measuring an environment
DE202010013825U1 (en) * 2010-10-04 2011-02-17 V&R Vision & Robotics Gmbh Portable 3D measuring device
EP2682783A1 (en) * 2012-07-03 2014-01-08 Zoller & Fröhlich GmbH Method and device for evaluating laser scans
DE102012109481A1 (en) 2012-10-05 2014-04-10 Faro Technologies, Inc. Device for optically scanning and measuring an environment

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