3-D scanning and positioning interface

• US 10,401,142 B2
• Filed: 06/26/2013
• Issued: 09/03/2019
• Est. Priority Date: 07/18/2012
• Status: Active Grant

• Current Assignee: Creaform, Inc. (Ametek Incorporated)
• Original Assignee: Creaform, Inc. (Ametek Incorporated)
• Inventors: Hebert, Patrick, Carette, Alexandre, Saint-Pierre, Eric
• Primary Examiner(s): Toatley, Jr., Gregory J
• Assistant Examiner(s): Becker, Brandon J
• Application Number:
  US14/405,430
• Publication Number:
  US 20150142378A1
• Time in Patent Office: 2,260 Days
• Field of Search: None
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G01B 2210/52 Combining or merging partially overlapping images to an overall image
• CPC Class Codes: G06T 2200/04 involving 3D image data
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: G06T 7/73 using feature-based methods

Abstract

A system and a method for providing an indication about positioning unreliability are described. The system comprises a scanner for scanning a surface geometry of an object and accumulating 3D points for each frame using shape-based positioning; a pose estimator for estimating an estimated pose for the scanner using the 3D points; an unreliable pose detector for determining if the estimated pose has an under constrained positioning and an indication generator for generating an indication that the unreliable pose estimation is detected. In one embodiment, a degree of freedom identifier identifies a problematic degree of freedom in the estimated pose. In one embodiment, a feature point detector detects a reobservable feature point and the pose estimator uses the feature point with the 3D points to estimate the estimated pose and the unreliable pose detector uses the feature point to identify the estimated pose as an unreliable pose estimation.

Claims

1. A system for providing an indication about positioning unreliability, the system comprising:

a scanner for scanning a surface geometry of an object and accumulating a set of 3D points for each frame of a plurality of frames using shape-based positioning for said scanner;

a feature point detector for detecting a presence of a feature point reobservable by said scanner in at least two of said plurality of frames, wherein the feature point is used for constraining at least one degree of freedom;

a pose estimator for estimating, using said set of 3D points and said feature point, an estimated pose for said scanner with respect to said object;

an unreliable pose detector for;

determining if said estimated pose has an underconstrained positioning including determining a geometry type by;

using a covariance matrix built using the set of 3D points and the feature point and which describes a quality of a fit of a frame as a function of a variation of said estimated pose;

extracting eigenvectors of said covariance matrix;

calculating a ratio of corresponding eigenvalues of said eigenvectors;

identifying at least on high ratio of said ratios using a predetermined threshold;

extracting at least one problematic eigenvector from said high ratio;

if a high ratio is identified, determining said surface geometry type to correspond to one of a plane and a sphere; and

, if said estimated pose has an underconstrained positioning, identifying said estimated pose as an unreliable pose estimation; and

an indication generator for generating an indication that said unreliable pose estimation is detected.

2. The system as claimed in claim 1, further comprising a degree of freedom identifier for identifying at least one problematic degree of freedom in said estimated pose, said degree of freedom identifier being triggered by said unreliable pose detector and wherein said indication generated by said indication generator includes information about at least one problematic degree of freedom with said indication.

3. The system as claimed in claim 2, wherein said indication generated by said indication generator includes information about all some of said at least one problematic degree of freedom.

4. The system as claimed in claim 1, further comprising a speaker, wherein said indication generator causes said speaker to emit an audible indication.

5. The system as claimed in claim 1, further comprising a visual interface, wherein said indication generator causes said visual interface to display a visual indication, wherein said visual indication is at least one of a text message and a graphical message.

6. The system as claimed in claim 5, further comprising a model builder, said model builder building a cumulative model of said geometry of said surface using said sets of 3D points, wherein said visual interface displays a graphical representation of said cumulative model and wherein said visual indication is superimposed on said graphical representation of said cumulative model.

7. The system as claimed in claim 5, further comprising a voxel sensitivity level calculator for accumulating an average for a voxel sensitivity level in all voxels of said cumulative model modified by said set of 3D points, wherein said visual interface displays said graphical representation of said cumulative model with a color corresponding to said voxel sensitivity level.

8. The system as claimed in claim 5, further comprising a frame selector for determining a level of unreliability of said unreliable pose estimation;

comparing said level of unreliability with a pre-determined unreliability threshold;

transferring said set of 3D points of each said frame to said model builder only if said level of unreliability is lower than said pre-determined unreliability threshold.

9. The system as claimed in claim 5, wherein said visual interface displays a graphical representation of a current frame of said scanning and wherein said visual indication is superimposed on said graphical representation of said current frame.

10. The system as claimed in claim 5, further comprising a pose sensitivity level attributor for attributing a pose sensitivity level to said estimated pose using said estimated pose, said pose sensitivity level attributor being triggered by said unreliable pose detector and wherein said indication generated by said indication generator includes information about said pose sensitivity level with said indication, wherein said information about said pose sensitivity level is a color of said visual indication.

11. The system as claimed in claim 5, further comprising

a degree of freedom identifier for identifying at least one problematic degree of freedom in said estimated pose, said unreliability degree of freedom identifier being triggered by said unreliable pose detector and wherein said indication generated by said indication generator includes information about at least one of said at least one problematic degree of freedom with said indication;

wherein said graphical message includes at least one arrow, said at least one arrow being displayed with an orientation corresponding to said at least one of said problematic degree of freedom.

12. The system as claimed in claim 1, further comprising a user command interface, said user command interface receiving a command from a user to perform a positioning reliability verification, wherein said unreliable pose detector and said indication generator are triggered by said command to generate said indication that said unreliable pose estimation is detected.

13. The system as claimed in claim 1, further comprising a temporal filter, said temporal filter triggering said indication generator to generate said indication when a number u of frames having an unreliable pose estimation in the n latest frames of said plurality of frames reaches a predetermined threshold.

14. A method for providing an indication about positioning unreliability, the method comprising:

scanning a surface geometry of an object and accumulating a set of 3D points for each frame of a plurality of frames using shape-based positioning;

estimating, using said set of 3D points, an estimated pose for said scanner with respect to said object;

determining if said estimated pose has an underconstrained positioning by;

using a covariance matrix which describes a quality of a fit of a frame as a function of a variation of said estimated pose;

extracting eigenvectors of said covariance matrix;

calculating a ratio of corresponding eigenvalues of said eigenvectors;

identifying at least one high ratio of said ratios using a predetermined threshold;

extracting at least one problematic eigenvector from said high ratio;

if there is a single high ratio, determining said surface geometry type to correspond to one of a linear extrusion, a surface of revolution and a helix;

if there are two high ratios, confirming said surface geometry type to correspond to a cylinder;

if there are three high ratios, determining said surface geometry type to correspond to one of plane and a sphere, and, if said estimated pose has an underconstrained positioning, identifying said estimated pose as an unreliable pose estimation;

generating an indication that said unreliable pose estimation is detected;

building a cumulative model of said geometry of said surface using said set of 3D points; and

displaying a graphical representation of said cumulative model and superimposing said visual indication on said graphical representation of said cumulative model at a location on the graphical representation of said cumulative model where said estimated nose is underconstrained.

15. A system for providing an indication about positioning unreliability, the system comprising:

a scanner for scanning a surface geometry of an object and accumulating a set of 3D points for each frame of a plurality of frames using shape-based positioning for said scanner;

a pose estimator for estimating, using said set of 3D points, an estimated pose for said scanner with respect to said object;

an unreliable pose detector for;

determining if said estimated pose has an underconstrained positioning by;

using a covariance matrix which describes a quality of a fit of a frame as a function of a variation of said estimated pose;

extracting eigenvectors of said covariance matrix;

calculating a ratio of corresponding eigenvalues of said eigenvectors;

identifying at least one high ratio of said ratios using a predetermined threshold;

extracting at least one problematic eigenvector from said high ratio;

if there is a single high ratio, determining said surface geometry type to correspond to one of a linear extrusion, a surface of revolution and a helix;

if there are two high ratios, confirming said surface geometry type to correspond to a cylinder; and

if there are three high ratios, determining said surface geometry type to correspond to one of a plane and a sphere, and, if said estimated pose has an underconstrained positioning, identifying said estimated pose as an unreliable pose estimation;

an indication generator for generating an indication that said unreliable pose estimation is detected;

a visual interface, wherein said indication generator causes said visual interface to display a visual indication, wherein said visual indication is at least one of a text message and a graphical message; and

a model builder, said model builder building a cumulative model of said geometry of said surface using said sets of 3D points, wherein said visual interface displays a graphical representation of said cumulative model and wherein said visual indication is superimposed on said graphical representation of said cumulative model at a location on the graphical representation of said cumulative model where said estimated pose is underconstrained.

16. The system as claimed in claim 15, further comprising a speaker, wherein said indication generator causes said speaker to emit an audible indication.

17. The system as claimed in claim 15, further comprising a voxel sensitivity level calculator for accumulating an average for a voxel sensitivity level in all voxels of said cumulative model modified by said set of 3D points, wherein said visual interface displays said graphical representation of said cumulative model with a color corresponding to said voxel sensitivity level.

18. The system as claimed in claim 15, further comprising a frame selector for determining a level of unreliability of said unreliable pose estimation;

comparing said level of unreliability with a pre-determined unreliability threshold;

transferring said set of 3D points of each said frame to said model builder only if said level of unreliability is lower than said pre-determined unreliability threshold.

19. The system as claimed in claim 15, further comprising a pose sensitivity level attributor for attributing a pose sensitivity level to said estimated pose using said estimated pose, said pose sensitivity level attributor being triggered by said unreliable pose detector and wherein said indication generated by said indication generator includes information about said pose sensitivity level with said indication, wherein said information about said pose sensitivity level is a color of said visual indication.

20. The system as claimed in claim 15, further comprising

a degree of freedom identifier for identifying at least one problematic degree of freedom in said estimated pose, said unreliability degree of freedom identifier being triggered by said unreliable pose detector and wherein said indication generated by said indication generator includes information about at least one of said at least one problematic degree of freedom with said indication;

wherein said graphical message includes at least one arrow, said at least one arrow being displayed with an orientation corresponding to said at least one of said problematic degree of freedom.

21. The system as claimed in claim 15, further comprising a user command interface, said user command interface receiving a command from a user to perform a positioning reliability verification, wherein said unreliable pose detector and said indication generator are triggered by said command to generate said indication that said unreliable pose estimation is detected.

22. The system as claimed in claim 15, further comprising a temporal filter, said temporal filter triggering said indication generator to generate said indication when a number u of frames having an unreliable pose estimation in the n latest frames of said plurality of frames reaches a predetermined threshold.

23. The system as claimed in claim 20, wherein the at least one arrow is curved to match the graphical representation of said cumulative model.

24. A method for providing an indication about positioning unreliability, the method comprising:

scanning a surface geometry of an object and accumulating a set of 3D points for each frame of a plurality of frames using shape-based positioning;

detecting a presence of a feature point reobservable by said scanner in at least two of said plurality of frames, wherein the feature point is used for constraining at least one degree of freedom;

estimating, using said set of 3D points and said feature point, an estimated pose for said scanner with respect to said object;

determining if said estimated pose has an underconstrained positioning including determining a geometry type by;

using a covariance matrix which describes a quality of a fit of a frame as a function of a variation of said estimated pose;

extracting eigenvectors of said covariance matrix;

calculating a ratio of corresponding eigenvalues of said eigenvectors;

identifying at least one high ratio of said ratios using a predetermined threshold;

extracting at least one problematic eigenvector from said high ratio;

if a high ratio is identified, determining said surface geometry type to correspond to one of a plane and a sphere; and

if said estimated pose has an underconstrained positioning, identifying said estimated pose as an unreliable pose estimation; and

generating an indication that said unreliable pose estimation is detected.