Verfahren zum Bereinigen von virtuellen Reprasentationen von Objekten

• US 20180104029A1
• Filed: 10/13/2017
• Published: 04/19/2018
• Est. Priority Date: 10/13/2016
• Status: Active Grant

• Current Assignee: A.Tron3D Gmbh
• Original Assignee: A.Tron3D Gmbh
• Inventors: JESENKO, Jurgen, KELZ, Engelbert
• Granted Patent: US 10,456,225 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61C 13/0004 Computer-assisted sizing or machining of dental prostheses
• CPC Class Codes: A61C 19/04 Measuring instruments specially adapted for dentistry A61C5/44 takes precedence; testing vitality of teeth A61B5/0534; radiation diagnosis specially adapted for dentistry A61B6/51
• CPC Class Codes: A61C 9/004 Means or methods for taking digitized impressions
• CPC Class Codes: A61C 9/0053 Optical means or methods, e.g. scanning the teeth by a laser or light beam
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]
• CPC Class Codes: G06T 19/20 Editing of 3D images, e.g. changing shapes or colours, aligning objects or positioning parts
• 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 2207/30036 Dental; Teeth
• CPC Class Codes: G06T 2219/2021 Shape modification
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06V 10/26 Segmentation of patterns in the image field; Cutting or merging of image elements to establish the pattern region, e.g. clustering-based techniques; Detection of occlusion
• CPC Class Codes: H04N 13/167 Synchronising or controlling image signals
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal

Abstract

A method for clearing unwanted data from optically detected virtual representations of objects includes: a. Defining an extension line of the representation; b. Generating a projection plane at one point of the extension line, which is perpendicular to the generated projection plane; c. Projecting all known points in space of the representation from one region on the projection plane onto the projection plane, the corresponding point in space being stored for each projected point; d. Generating a two-dimensional curve on the projection plane; e. Determining maxima, minima and a center of the curve; f. Identifying projected points of the curve that—viewed from the center of the curve-lie outside of the minima or maxima; g. Removing the points in space that correspond to the projected points that were identified in step f.; and h. Optionally, repeating starting from step b. for one further point of the extension line.

Claims

1. Method for clearing, in particular for removing, unwanted data from optically detected virtual representations of objects, in particular teeth and intraoral structures, the method comprising:

a. Defining an extension line of the representation,

b. Generating a projection plane at one point of the extension line, the extension line at this point being perpendicular to the generated projection plane,

c. Projecting all known points in space of the representation from one region on the projection plane onto the projection plane, the corresponding point in space being stored for each projected point,

d. Generating a two-dimensional curve on the projection plane from the projected points,

e. Determining maxima, minima and a center of the curve,

f. Identifying projected points of the curve that—

viewed from the center of the curve-lie outside of the minima or maxima,

g. Removing the points in space that correspond to the projected points that were identified in step f.,

h. Optionally, repeating starting from step b. for one further point of the extension line.

2. Method according to claim 1, wherein between steps a. and b., the step

a1. Subdividing of the extension line into points for the generation of projection planes takes place.

3. Method according to claim 2, wherein two neighboring projection planes at border one segment of the representation.

4. Method according to claim 3, wherein the region in step c. is formed by at least one segment that borders the projection plane.

5. Method according to claim 4, wherein the points in space of each segment are projected at least once.

6. Method according to claim 1, wherein the projection in step c. takes place along perpendiculars of the projection plane.

7. Method according to claim 1, wherein the curve in step d. is generated by linear interpolation of the projected points on the generated projection plane.

8. Method according to claim 1, wherein the curve is smoothed.

9. Method according to claim 1, wherein the definition of the extension line in step a. contains the following steps:

a.i. Determining features in the representation,

a.ii. Generating a two-dimensional point cloud by projection of points, on which

features are located, onto an extension projection plane,

a.iii. Forming of a graph that runs along the point cloud generated in a.ii.,

a.iv. Defining the graph generated in a.iii. as an extension line.

10. Method according to claim 1, wherein the definition of the extension line in step a. contains the following steps:

i. Determining the eigenvectors of the representation,

ii. Defining the longest eigenvector as the direction of the extension line,

iii. Defining the length of the representation along the longest eigenvector as the length of the extension line.

11. Method according to claim 1, wherein the virtual representation is a TSDF.

12. Method according to claim 1, wherein the represented objects are teeth and that the representation depicts at least two succeeding teeth.

13. Method according to claim 2, wherein step h. takes place until steps b. to g. have taken place for all points for generating projection planes from step a1.

14. Method according to claim 1, wherein the extension line is a sequence of interconnected straight lines.

15. The method of claim 2, wherein in step a1, the points are distributed equidistantly.

16. The method according to of claim 7, wherein the curve in step d. is generated by equidistant linear interpolation of the projected points on the generated projection plane.

17. The method according to claim 8, wherein the curve is smoothed by repeated and/or inverse execution of a Fourier transform.

18. The method of claim 12, wherein the representation depicts at least three succeeding teeth.

19. Method according to claim 2, wherein the projection in step c. takes place along perpendiculars of the projection plane.

20. Method according to claim 3, wherein the projection in step c. takes place along perpendiculars of the projection plane.