JPH05265659A - System and method for digitization - Google Patents

Abstract

PURPOSE: To digitize a three-dimensional body uniformly with high resolution. CONSTITUTION: The cavity in a three-dimensional body 10 and the outside volume of the body are filled with a nearly opaque base material 14, which is solidified into a solid block having nearly uniform hardness. After a 1st exposed surface is digitized, a layer of specific thickness is removed from the body to expose a 2nd exposed surface, which is digitized. This operation is carried on until the whole volume of the body is digitized. This digitizing method solves positioning problems between digitizing processes of respective surfaces differently from a method which digitizes layer surfaces after removal from the solid block.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the digitization of three-dimensional objects.

[0002]

The usefulness of digitizing three-dimensional objects is well established. There are known three-dimensional digitizing devices that operate to digitize only the envelope. These devices include, for example, a mechanical arm that follows the outer surface of the object, and the coordinates of the tip of the arm are determined by a shaft encoder at the arm joint. Another example of such a digitizer uses a stylus that points to a position on the surface of the object, the coordinates of the tip of the needle being determined by telemetry. Another example of such a device is to measure the reflection of an energy beam, such as light, that is reflected at the outer contour of an object.

A typical mechanical arm digitizer is described in "Digital Design, April 1984, p. 104", from Micro Control, Vernon CT, USA.
It is marked as available under the name D Digitizer.

A typical telemetry digitizer, known as 3-Space, is a McDonne of St. Louis, MO, USA.
Available from ll Douglas.

An apparatus for converting three-dimensional points measured on some surfaces into a CAD model is CADD Inspec.
Known as tor, CAD from Vernon, CT, USA
Available from KEY ”Klein Report, Vol. 10, N
o. 13, July 1988 ”.

It is also known to produce a three-dimensional image of a relatively soft tissue that is cut with a microtome. This technique does not provide image registration and is not suitable for engineering.

Computerized tomography and radiation scanners provide slice information for an object, but generally in terms of its speed, model size capacity, accuracy, resolution, and the type of material it can handle. , Not suitable for use in industrial environment.

Prothero JS et al., "Three-dimensional reconstruction from continuous sections: Reassembly problem (Tree-dimension
al reconstruction from serial sections: iv. The re
assembly problem) ”(Computer. & Biomed. Res. (US
A), vol. 19, No. 4, pp. 361-373, August 1986) describes a reconstruction technique in which thin slices are sequentially cut from an object. After cutting, the slices are digitized by conventional two-dimensional digitization techniques.

H. Harlyn Baker, “Building, Visualizing, and Computing on Motion Surfaces (Buildin
g, visualizing and computing on surfaces of evolut
ion) ”(IEEE Computer Graphics & Applications, 19
(July 1988, pp. 31-41), the article
There is discussion about reconstructing a dimensional surface from its two-dimensional slices.

US Pat. Nos. 3,649,108 and 3,884,563 both relate to layer-by-layer photography of test specimens. Certain layers are removed from the specimen after imaging and disposed of. U.S. Pat. No. 3,884,563
The issue, column 2, line 15, describes the use of a computer scanner. U.S. Pat. No. 3,649,108
No. 3, lines 16-20, describes the use of fillers, which are usually translucent or transparent.

It can be said that the above-described prior art devices cannot uniformly and stereoscopically digitize objects of all shapes.

[0012]

The present invention seeks to provide a highly accurate system for digitizing a three-dimensional object.

[0013]

In order to achieve the above object, a system for stereoscopic digitization of a three-dimensional object provided according to a preferred embodiment of the present invention is provided before performing the digitization. A device for filling a cavity in a three-dimensional object and a volume outside the object with a substantially opaque support material to solidify the support material into a solid block having a substantially uniform hardness, and a first exposed surface of the object is digitalized. An apparatus for digitizing the first exposed surface and an apparatus for operating following the digitization of the first exposed surface to remove a layer of a predetermined thickness of the object to expose the second exposed surface and a second exposed surface of the object. And a device that operates as described above.

Further in accordance with an embodiment of the present invention, an apparatus for digitizing an exposed substantially two-dimensional surface and a layer of a predetermined thickness of an object is selectively removed to remove the substantially two-dimensional surface. A device for exposing and a digitizing device for digitizing the first exposed surface of the object and a selective removing device for the first.
Control subsequent to digitizing the exposed surface of the object to remove a layer of a predetermined thickness from the object to expose the second exposed surface and cause the digitizing device to digitize the second exposed surface of the object. A device for stereoscopic digitization of a three-dimensional object is provided.

Still further, the method for digitizing a three-dimensional object provided in accordance with a preferred embodiment of the present invention provides a method for digitizing a three-dimensional object cavity and an outer volume of the object before performing the digitization. Filling with an opaque support material to solidify the support material into a solid block having a substantially uniform hardness, digitizing the first exposed surface of the object, followed by digitizing the first exposed surface. Removing a layer of a predetermined thickness from the object to expose the second exposed surface, and digitizing the second exposed surface of the object.

The operation of further removing the layer after digitization to expose the next surface and its digitizing operation is continued until the entire volume of the object has been digitized.

According to a preferred embodiment of the present invention, prior to the above digitizing process, the cavities within the three-dimensional object and the volume outside the object are filled with a support material into a solid block having a substantially uniform hardness. Is solidified.

Further in accordance with a preferred embodiment of the present invention,
The removal of a layer of a given thickness on the object is carried out by machining.

Still further in accordance with a preferred embodiment of the present invention, the color of the support material is different from the color of the object to provide contrast. The support material is preferably opaque to prevent false readings by light passing from the deeper layers to the digitizing surface.

Further in accordance with a preferred embodiment of the present invention, 2
Digitization of the dimensional surface is merged into a standard CAD format, a three-dimensional display.

Still further in accordance with a preferred embodiment of the present invention, digitization is performed with a computerized automated inspection system.

Positioning problems between digitizations of various surfaces by performing a two-dimensional digitization on the surface of the layer before it was removed from the solid block, rather than on the surface of the layer already removed from the solid block. It is a feature of the invention that the is eliminated.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the basic principles of the present invention are shown. An object 10 such as a vase is first subjected to a process, here referred to as a coagulation procedure, in a preparation cell 12.
As described in more detail below, the internal cavity of the body 10 is filled with a filling material 14. The volume outside the body is filled to define a solid cube 16 or other suitable shape in which the body 10 is embedded.

The filling material 14 used to fill both the interior and exterior of the body 10 within the cube 16 is the body 1
Preferably, the material has a hardness similar to 0 hardness. Further, the filling material has a color different from the color of the object 10,
It is desirable to be opaque.

The cube 16 is a work piece (workpiece) designated by the reference numeral 20 and supported on an elevating tray 22.
To define The tray 22 is supported at a variable height on a moving table (carriage) 24 that can move in the XY plane.

Workpiece 20 is A from Newport Beach, CA.
A camera 26 for providing a two-dimensional photograph of a substantially two-dimensional surface, such as a CCD camera available from udre, a new two by removing a predetermined or selective thickness from an object.
Milling head (milling for exposing dimensional surface)
head) 28 and optical cleanup assembly 2 to prepare the newly exposed surface for camera 26
9 repeatedly and sequentially and sequentially engages and disengages.
The camera 26 is an Optrotech Ltd. of Nes Ziona, Israel.
Preferably, it forms part of a computerized inspection system such as the Vision-106 inspection system commercially available from Another commercially available system is Hartford, CT.
M from Gerber Scientific Instruments Co. of
odel 1850 Automatic optical inspection system.

The output of camera 26, in raw data format, preferably digital raster format, is provided to a computer system 30, such as an IBM PC. Computer system 30 is a McDonnell D from St. Louis, Missouri, USA.
Unigraphics system from ouglas Automation
A computer aided design (CAD) output 31 is prepared in a conventional format for use by a conventional commercial CAD system 32 such as. For an overview of algorithms and systems for such applications, see "ComputerVision, G.
raphics and Image Processing, No. 41, pp. 346-381 "
RT Chin's Survey of Automated Visual Inspection (Surve
y-Automated Visual Inspection 1981-1987) ”.

The operating sequence of the device of FIG. 1 is summarized as follows. The object 10 or one or more objects to be stereoscopically digitized in accordance with the present invention is placed in a suitable framing container defining a preparation cell 12 and, if desired,
It is held in place by solid ribs. The solid ribs are preferably made of a support material similar or identical to the support material used during solidification in the following steps.

A solidifiable liquid support material 14, such as cast wax, polystyrene foam, gypsum or epoxy, for example, fills the interior volume of the preparation cell 12 (FIG. 1) so as to fill the voids of the body and the body. It is inserted all around. Upon fixation and solidification of the support material 14, a cube or other suitable solid 16 is defined, the contour of which corresponds to the contour of the preparation cell 12. At this point, the solid 16 may be removed from the cell 12. Alternatively, the cell 12 may be removed. Alternatively, and more preferably, the solid 16 is retained within the cell 12, as shown in FIG.

The support material 14 has a number of important functions such as: * Support the precision part of the object and prevent distortion of the object due to milling. * Providing a visual contrast between the object and the background so that accurate imaging is achieved. * To preserve imaging accuracy by obscuring parts of the object that have been removed from the exposed 2D layer. * Allowing tools and markers to be placed in desired positions with respect to the object being digitized. * Allowing multiple objects to be digitized in the same preparation cell at the same time.

The solid 16 defining the work piece 20 is then placed on the lift tray 22 with the top of the work piece operating level engaging the camera 26, milling head 28 and cleanup unit 29. Is located in.

The appropriate vertical resolution is selected. A typical resolution is 0.1 mm.

Operation is initiated by raising the tray by one unit of resolution (typically 0.1 mm), moving the tray across the milling head and removing a layer one resolution unit thick. To be done. The exposed layer is then treated by the device 29, such as by wetting the exposed surface of the layer with a transparent liquid such as water or alcohol, to enhance the contrast between the object and the support material 14.

The contrast-enhanced surface of the exposed layer is scanned or photographed by camera 26 to produce a digital raster image.

The digital image is processed and the above steps are repeated until the entire object is sliced at the desired resolution and each of its layers is imaged.

The digital raster images of the various layers are combined and modified to produce a conventional CAD data file output.

FIG. 2 is a pictorial view of a relatively complex object that can be easily digitized in accordance with the present invention.

Slicing of a three-dimensional object is shown in FIG.
It can be easily visualized by considering FIG. 3C. FIG. 3A shows an object. FIG. 3B shows the layer pattern overlaid on the object. FIG. 3C shows an object with layers 3 to 3 removed to expose layer 4.

It will be appreciated that the device of the present invention has many possible applications. For example, the following items are included. * Digitization of 3D objects. * When combined with an appropriate output device, produces many scaled-up and / or scaled-down variants of existing objects. * Testing cast molds and dies by digitizing the molded or cast product and comparing it to its design dimensions. Updating the CAD file after the physical model has been physically modified by adding and / or reducing materials. * Standard CAD compatible with commercial CAD databases
Converting physical objects into files.

Next, FIG. 4 will be described. FIG. 4 is a schematic pictorial view of a portion of the apparatus of FIG. Mobile stand 24
Can have a Z-axis lifting mechanism 40 that supports the tray 22. The cube 16 is arranged on the tray 22. Note that the cube 16 may be surrounded by the initially placed preparation cell container 12.

The milling head 28 (FIG. 1) typically comprises a fly cutter 44 of conventional design, such as is commercially available from Iscar Ltd. of Israel. The fly cutter 44 is driven by a motor 46 and is connected to a vacuum cleaner 48 and a dust trap 50 for controlling and collecting dust.

The optical cleanup device 29 typically comprises a wet rotating brush or a row of jet sprinklers 52. The camera 26 (FIG. 1) typically comprises a digital video camera 54 associated with a lighting device 56 and a control computer 58. They are,
Vision 106 above manufactured by Optrotech Ltd.
As used in inspection systems.

It will be appreciated that the orientation of the object 10 in the preparation cell 12 determines the coordinates specified by the system prior to the modification of the coordinates. FIG. 5A shows that piston 60 is used to press object 62 against the bottom of preparation cell 64 filled with support material 66 such that the flat bottom of object 62 is along the flat bottom of preparation cell 64. Is shown.

FIG. 5B shows the object 66 suspended in a preparation cell 68 filled with a support material 70. Preferably, the body 66 is attached to a support rod 72 formed of solidified support material 70. Rod 72
Are held in the correct position by the support member 74.

Referring now to FIGS. 6A-6F, various stages of preparing an object having an internal cavity for digitization in accordance with the present invention are shown. A typical object 80 having an internal cavity 82 is shown in Figure 6A. The inner cavity 82 is filled with a support material 84 as shown in FIG. 6B and the filled body is shown in FIG. 6C. The object is then placed in the preparation cell 86 and then the volume outside the object 80 is filled with support material. The filled preparation cell is shown in FIG. 6E. The solidified cube 88 is shown in Figure 6F. In this case, as an example, it can be seen that the top and bottom are reversed. This orientation is the preferred orientation for digitization, especially if a preparation cell of the type shown in FIG. 9 is used, or if it is desired to avoid milling the support material above the object. The cube 88 may be with the preparation cell 86 or after the preparation cell 86 is removed.
Machined.

As mentioned above, various tools or reference indicators are digitized with the object. This is desirable when it is desired to instruct the computer to make some changes to the object being digitized at the predetermined locations that can be indicated by the markers. Markers can also be used to indicate possible separations between CAD files or parts of CAD files.

FIG. 7A shows an area 90 on the object 92 where it is desired to mark. In FIG. 7B, region 9
0 is coated with a relatively thick layer of paint 94 or other marking material. FIG. 7C shows a typical cross section of the marked object of FIG. 7B placed in a preparation cell 96 filled with support material 98.

FIG. 7D is an enlarged view of the circular portion shown in FIG. 7C. The interface between the three different colors, namely the object 92 and the marking material 94, the marking material 9
4 and the support material 98, and the object 92 and the support material 98.
Between and are defined and described. Optrote above
Standard edge detection software used in the ch Vision 106 system can be used to vectorize each of the above interfaces.

FIG. 7E shows the result of vectorization. Two different lists of vectors 100 and 102 are defined along the interface between the object 92 and the support material 98, and the interface between the object 92 and the marking material 94, respectively. Note that the interface between marking material 94 and support material 98 is irrelevant and should be ignored. When two different lists of vectors are accumulated between layers, they define separate surfaces for which marking is desired.

Some preferred materials for use as the support material are listed below. * Casting wax such as Type 999 available from Argueso, Mamaroneck, New York, USA * "Modern Plastics Encyclopedia, McGraw Hill, 198"
8 "Polystyrene foam as described on page 79 * Epoxy such as cast epoxy type 3142-66E available from Delta Chemicals of Ramat Gan, Israel * Gypsum

8A-8D show various techniques for inserting support material into and around the object to be digitized. In the drawing, pouring
) Is indicated by reference numeral 101, and injecting is indicated by reference numeral 103. The internal cavity 104 of the object 106 may be prefilled outside the preparation cell as shown in FIG. 8B. Pre-filled object 106
Is then placed in the preparation cell 108 and further filled with support material 110 as shown in FIG. 8C. This two-stage filling technique is particularly useful when the more direct technique can produce bubbles.

According to another example, the solidified support material 118
And so on, outside the preparation cell, for use in the correct object orientation with respect to the given surface 116.
2 may be cast onto the object 114.

According to another embodiment of the present invention, the object may be coated by any desired technique such as dipping and spraying.

Referring now to FIG. 9, patterned recess 1
A preparation cell 120 is shown defining 22 at its bottom. This provides a two dimensional pattern that, when machined, represents the orientation error of the preparation cell 120 with respect to the coordinate system of the digitizing system. Therefore, the moving table 2
4 and tray 22 (FIG. 1) have devices for adjusting the position of the preparation cell 120 according to the measured position error prior to digitization.

The particular recess structure shown in FIG. 9 has a number of advantages. a. The error is divided into an X component and a Y component. b. It becomes more sensitive as machining continues towards the object to be digitized.

10A-10D show a preparation cell 120 having a reference recess 122 of the type shown in FIG.
Using, the various steps of preparing an object for digitization are shown. As shown in FIG. 10B,
The object 130 is placed at the bottom of the preparation cell 120 above the recess 122. After the object is filled with the support material 132 as shown in FIG. 10C, the remaining portion of the preparation cell 120 is filled as shown in FIG. 10D.

As shown in FIG. 10E, the support material 13
After solidifying the two, the preparation cell is inverted and mounted on an adjustable support assembly 134 for machining, such as by fly cutter 136. FIG. 10F shows the preparation cell 120 in a substantially horizontal orientation. Figure 10G
Indicates a preparation cell in a non-horizontal orientation. 11A and 11B show the recess 122 when the first layer is removed.
The situation is shown. It can be seen from the appearance of the concave portion 122 that the levelness can be determined and appropriate adjustment can be performed. FIG. 12 shows details of the base assembly 134 including spring-loaded mounting screws 140 for orienting the preparation cell 120 on the base 134 to achieve the desired leveling.

[0058]

Since the system of the present invention is constructed as described above, a three-dimensional object can be digitized extremely accurately.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a digitizing system constructed and operated in accordance with a preferred embodiment of the present invention.

FIG. 2 is a pictorial diagram of an object that can be digitized using the systems and techniques of the present invention.

3A, 3B and 3C are diagrams of slicing of an object.

FIG. 4 is a pictorial diagram of a portion of the digitizing system of FIG.

5A and B are pictorial illustrations of two different techniques for holding an object in a desired position during solidification of a support material.

FIG. 6A, B, C, D, E and F are diagrams of steps in a coagulation technique useful in the present invention.

7A, B, C, D and E are different levels of diagrams detailing features of the present invention.

8A, B, C and D are diagrams of four stages in a coagulation technique useful in the present invention.

FIG. 9 is a pictorial view of a coagulation container with a molded reference mark.

10A, B, C, D, E, F and G show various stages in a solidification step using the container of FIG.

11A and B are FIGS. 10F and 10G, respectively.
It is sectional drawing about the line AA of FIG.

FIG. 12 is a detail view of the mounting of the cover on the container of FIG. 9.

[Explanation of symbols]

 10 Object 12 Preparation Cell 14 Filling Material 20 Workpiece 22 Elevating Tray 24 Moving Stand 26 Camera 28 Milling Head 29 Optical Cleanup Device 30 Computer System 32 CAD System

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Itzchak Pomeranz Kfar Saba Gorombu Street, Israel 18

Claims (20)

[Claims] 1. A system for three-dimensionally digitizing a three-dimensional object having a cavity, wherein the volume inside the three-dimensional object and the volume outside the object are substantially opaque before performing the digitization. Means for filling with a support material and solidifying said support material into a solid block having a substantially uniform hardness; means for digitizing the first exposed surface of the object; and digitizing the first exposed surface. And a machining means including a fly cutter for removing a layer of a predetermined thickness from the object to expose a second exposed surface of the object without substantially distorting the rest of the object. Means for digitizing the second exposed surface of the object; 2. A system for three-dimensionally digitizing a three-dimensional object having a cavity, wherein said cavity within the three-dimensional object and the volume outside the object are substantially opaque before performing the digitization. Means for filling with a support material and solidifying said support material into a solid block having a substantially uniform hardness; means for digitizing an approximately two-dimensional exposed surface of the object; and a layer of predetermined thickness from the object. Machining means including a fly cutter for selectively removing to expose a substantially two-dimensional surface; digitizing means for digitizing the first exposed surface of the object; and selectively removing means for the first exposed surface. Control means operative to remove a predetermined thickness layer of the object to expose the second exposed surface of the object and the digitizing means operates to digitize the second exposed surface of the object. Equipped with Digital system. 3. A method for digitizing a three-dimensional object containing a cavity, wherein the volume outside the cavity and the object within the three-dimensional object is substantially opaque before performing the digitization. Filling with a material and solidifying the support material into a solid block having a substantially uniform hardness; digitizing a first exposed surface of the object; and digitizing the first exposed surface, followed by the object Machining a layer of a predetermined thickness from to provide a second exposed surface of the object; and digitizing the second exposed surface of the object. 4. The steps of digitizing a surface and then machining further layers to expose the next surface and digitizing the next surface are continued until the entire volume of the object is digitized. The digitizing method according to claim 3. 5. The digitizing system according to claim 1, wherein the removing means includes a fly cutter. 6. The digitizing system according to claim 2, wherein the removing means includes a fly cutter. 7. The digitizing method according to claim 3, wherein the removing step includes fly cutting. 8. The digitizing method according to claim 4, wherein the removing step includes fly cutting. 9. The digitizing system of claim 1, wherein the color of the support material is different from the color of the object to provide contrast. 10. The digitizing system of claim 2, wherein the color of the support material is different from the color of the object to provide contrast. 11. The method of digitizing according to claim 3, wherein the contrast is provided by the color of the support material being different from the color of the object. 12. The digitization method of claim 4, wherein the contrast is provided by the color of the support material being different from the color of the object. 13. The digitization system of claim 1, further comprising means for merging digitizations of a plurality of two-dimensional surfaces into a three-dimensional representation. 14. The digitization system of claim 2, further comprising means for merging digitizations of a plurality of two-dimensional surfaces into a three-dimensional representation. 15. The digitization method of claim 3, further comprising the step of merging digitizations of a plurality of two-dimensional surfaces into a three-dimensional representation. 16. The digitization method of claim 4, further comprising the step of merging a plurality of digitized two-dimensional surfaces into a three-dimensional representation. 17. The digitizing system according to claim 14, wherein the three-dimensional display is a CAD display. 18. The digitizing method according to claim 15, wherein the three-dimensional display is a CAD display. 19. A system for stereoscopic digitization of a three-dimensional object for filling and solidifying a hollow three-dimensional object into a solid block having a substantially uniform hardness before performing the digitization. Means for digitizing the first exposed surface of the object, and a means for digitizing the first exposed surface, the means for digitizing the first exposed surface of the object to determine the predetermined portion of the object without substantially distorting the rest of the object. A digitizing system comprising: fly-cutter means for removing a thick layer to expose a second exposed surface of an object; and means for digitizing a second exposed surface of the object. 20. A method for digitizing a hollow three-dimensional object, the method comprising solidifying the hollow three-dimensional object in a solid block having a substantially uniform hardness before performing the digitization. Digitizing a first exposed surface of the object, and digitizing the first exposed surface followed by fly-cutting a layer of a predetermined thickness from the object to provide a second exposed surface of the object. Digitizing the second exposed surface of the object, the digitizing method.