Optical means for making measurements of surface contours

• US 4,846,577 A
• Filed: 04/30/1987
• Issued: 07/11/1989
• Est. Priority Date: 04/30/1987
• Status: Expired due to Term

• Current Assignee: P&W/Lbp Master Partnership
• Original Assignee: LBP Partnership
• Inventors: Grindon, John R.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US07/044,992
• Time in Patent Office: 803 Days
• Field of Search: 356/376, 356/1, 356/9
• US Class Current: 356/610
• CPC Class Codes: G01B 11/2536 using several gratings with variable grating pitch, projected on the object with the same angle of incidence
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

A system for producing data to represent the three-dimensional shape of a surface including a projector for projecting patterns onto the surface. A sensor for producing representations of selected imaged patterns as projected onto the surface, and a device containing data that represents the relative positions of the projector and the sensor for processing data produced by sensor to generate output data that is representative of the shape of the surface.

Claims

1. A system for creating data to represent a three-dimensional surface shape comprising

means projecting on the surface shape distinctive patterns made up of adjacent pattern portions represented by distinctively differently positioned linear features formed by and between adjacent projected areas having differing optical characteristics, the linear features being positionally located according to a code such that the positions of the linear features projected by at least some of the different patterns are located at different distinct locations such that none of said linear features as projected are at the same location;

image sensor means positioned at a spaced location from the surface shape in position to observe the distinctive projected patterns including the linear features thereof projected on the surface shape, said sensor means including means for producing representations of selected ones of the distinctive linear features formed by the projected pattern portions, and

means for processing at least two image representations of projected patterns projected on the surface shape and sensed by the sensor means, said processing means containing processing data representative of the relative positions in space of the projection means and the image sensor means, said processing means further including means for extracting information from the different image representations to establish data representative of the location in space of different points on the surface shape.

2. The system of claim 1 wherein the detectable linear features are relatively uniformly distributed among the patterns.

3. A system for representing the three-dimensional surface shape of an object, the system including radiant energy projection means for projecting energy containing distinctive patterns of adjacent areas for projection onto the object whose surface shape is to be represented, the patterns defining on the object a plurality of distinctively located profile lines defined by the linear boundary between each pair of adjacent distinctive areas in the projected patterns, the boundaries in each pattern being positioned according to a code such that the locations of the boundaries in at least some of the different patterns are at different distinct locations such that none of the linear boundaries of said projected different patterns will fall on the object at the same location,

image sensor means positioned to observe the patterns projected onto the surface of the object, said sensor means including means for producing representations of selected ones of the projected patterns including the profile lines, and

means for processing the data observed and produced as representations by the sensor means in at least two distinct patterns, said processing means containing processing data representative of the relative positions in space of the projection means and the image sensor means, said processing means further including means for correlating data from the different image representations taking into account the relative positions of the projector and sensor means for producing therefrom data representations of different locations in space that correspond to the locations of profile lines where they occur on the object.

4. The system of claim 3 wherein the linear boundary lines are relatively uniformly distributed among the patterns.

5. A system for use in representing the three-dimensional surface shape of an object, the system including radiant energy projection means, means responsive to energy projected by the projection means and control means for the projection and responsive means, the projection means including a source of energy capable of being controlled to produce projected energy flashes, means to focus radiant energy from the projection means onto an object whose surface shape is to be represented, and an energy transmissivity encoding member mounted in alignment with the energy source and the focusing means, said encoding member having a pattern formed thereon by a plurality of adjacent relatively energy conducting and non energy-conducting areas arranged to extend over a portion of the surface thereof in the region aligned with the energy source and the focusing means, the pattern being segmented into a plurality of discrete segments each having distinctively positioned locations and widths corresponding to the energy conducting and non energy-conducting areas thereof so that regardless of which segment is positioned in alignment with the energy source and its associated focusing means at the time a flash from the energy source is projected, the projected energy will produce a distinctive intensity pattern on the surface of the object defining on the object a plurality of distinctly located profile lines at locations defined by each pair of adjacent energy conducting and non-energy conducting areas on the encoding member.

6. The system of claim 5 wherein the source of energy is a light source and the energy conducting and non energy-conducting areas on the encoding member are substantially light conducting and substantially non light-conducting areas on the encoding member.

7. The system of claim 5 wherein the locations and widths of the light conducting and non light-conducting areas on the encoding member are determined by a code having distinct code portions that determine the locations and widths of each of the light conducting and non light-conducting areas in each segment of the pattern.

8. The system of claim 5 wherein the code is a concatenated binary code having a distinctive sub-portion associated with each pattern segment, each sub-portion having a plurality of positions representing respectively each of the light conducting and non light-conducting areas of each of the corresponding pattern segments.

9. The system of claim 5 including a light tight enclosure having positions therein for mounting an object to be represented, said light enclosure also having spaced positions therein for mounting a plurality of projection means and a plurality of light responsive means.

10. The system of claim 5 wherein the projection means has a housing with means therein for rotatably supporting the encoding member the encoding member being optically encoded, spaced first and second sources of light in the housing at locations on one side of the optically encoding member, and a separate lens assembly associated with the first and second light sources in position to focus light from the respective light sources onto the object.

11. The system of claim 5 wherein the means responsive include video camera means and means associated therewith to produce a raster onto which the images formed from the patterns projected onto the object by the projection means as viewed thereby can be registered.

12. The system of claim 5 wherein the positions and the widths of the light conducting and non light-conducting areas on the encoding member are established according to a multi-position code having one position for each light conducting and one position for each non light-conducting area in each segment.

13. The system of claim 12 wherein each code position is represented by a six-bit binary word.

14. The system of claim 13 including a solution code associated with the multi-position code, said solution code having a plurality of positions each of which corresponds to one or more positions in the multi-position code.

15. Means for producing a measured representation of a boundary formed by and between adjacent lighted and non-lighted areas projected onto an object comprising

a projector having a light source and a lens system positioned for projecting light from said source onto an object,

a film member positioned in alignment with the light source and the lens system, said film member having at least two adjacent distinct areas each formed of differently optically encoded patterns including patterns formed by adjacent relatively transparent and opaque areas through which light from the light source passes as it is projected by the lens system onto the object,

means to move the film member in relation to the light source whereby at least two distinct areas of encoded patterns are projected onto the object at different times,

camera means spaced from the projector and oriented to view the object and at least a portion of the encoded patterns projected thereon by the projector, said camera means having a lens system focused on the object and on an image plane in the camera means onto which the viewed pattern on the object is focused,

means for electronically producing a separate grid pattern onto which the different focused patterns of the object as seen by the camera means are applied when each of the distinct differently optically encoded patterns is projected thereon to produce image representations thereof on the respective separate grid patterns,

means for storing the separate representations produced when the at least two differently optically encoded patterns on the film member are projected onto the object,

means including first image scanning means for producing at least one pair of image coordinate measurements representative of selected locations on one of the grid patterns, said measurement pair for each location identifying the coordinates of the location on the grid pattern where a linear feature occurs as formed by and between adjacent transparent and opaque encoded areas on the film member as projected onto the object occurs, another measurement indicating whether the light transition occuring thereat as sensed by the scanning means is from a light to dark or from a dark to light transition in the projected pattern, and

means including other image scanning means for producing another bit of information from the grid pattern onto which the different optically encoded patterns are projected, said other scanning means responding to the location information produced by the first scanning means to produce information for each location for which measurement pairs are produced indicating at the corresponding locations on the grid pattern whether that location on the grid pattern on which the different optically encoded images are projected is in a light or dark portion of the pattern.

16. The means of claim 15 including means for storing information representative of the location on the respective grid patterns where at least two linear features occur, and

computer means programmed to produce a three dimensional representation of at least a portion of the object along which one of said linear features occurs, said one linear feature being produced by the projector projecting one of said optically encoded images onto the object and by the camera means viewing at least a portion of one of the linear features from its different orientation relative to the projector.

17. Means for projecting optically encoded patterns onto a remote location comprising a projector having a spaced light source and lens system and optically encoded pattern forming means positioned in optical alignment therewith, said pattern forming means including a disc having annular patterns of light encoded areas positioned thereon, means for rotating the disc so that the annular encoded areas move relative to the light source and the lens system, the annular area including a plurality of adjacent circumferentially positioned segments each formed by a plurality of adjacent light conducting and non light-conducting areas capable of projecting patterns which are characterized by having distinct boundary lines formed by and between each adjacent light conducting and non light-conducting area, the locations of the boundary lines projected by the areas in each segment being located at distinctively different positions.

18. The means of claim 17 wherein the coded light conducting and non light-conducting areas are circumferentially extended elongated areas.

19. The means of claim 18 wherein the locations of the light conducting and non light-conducting areas in the different segments are determined according to a code characterized by a base subpattern of coded information including a distinct first set of bit information for each segment, said bit information for each set corresponding to a unit width measure of displacement along the width of said segment, said sets including bits of information representative of the width of the light conducting and the non light-conducting areas and hence the locations where the projected linear features occur, the formula for the code being such that no two linear features occur at the same location.

20. The means of claim 19 wherein information in each set is such that all projected linear features are separated by a predetermined minimum distance.

21. The means of claim 20 wherein said minimum separation distance is 3 unit widths of displacement.

22. The means of claim 17 wherein the locations of light-conducting areas and non light-conducting areas on the encoded disc are determined by trial and error.

23. The means of claim 19 including a second subpattern of coded information for extending the base subpattern of coded information to create a longer pattern of coded information, said second subpattern being derived from said base subpattern.

24. The meass of claim 23 wherein said second subpattern is derived from said base subpattern by cycling and shortening said base subpattern such that the longer pattern maintains compliance with the formula code used to create the base subpattern.

25. The means of claim 24 including additional subpatterns for further extending the longer pattern, said additional subpatterns being derived from the existing base and second subpattern.

26. A system for creating data to represent a non-patterned image of a three-dimensional surface comprising

means for projecting onto the surface a sequence of patterns formed by passing light through patterned masks chosen such that selected locations on the surface are illuminated by at least one of the projected patterns in the sequence,

sensor means positioned at a spaced location from the surface in position to observe distinctive projected pattern views on the surface and to produce image representations thereof, and

means for processing image representations of at least two projected pattern views as observed by the sensor means, said processing means including means establishing a maximum intensity of the images at predetermined locations of the images being viewed containing processing data representative of the relative positions in space of the surface to be represented, the projection means and the sensor means, said processing means establishing at predetermined locations of a selected one of the image representations a maximum intensity of selected images thereat.