METHODS AND APPARATUSES FOR FORMING A THREE-DIMENSIONAL VOLUMETRIC MODEL OF A SUBJECT'S TEETH

• US 20180028064A1
• Filed: 07/27/2017
• Published: 02/01/2018
• Est. Priority Date: 07/27/2016
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Avi Kopelman, Erez Lampert, Maayan Moshe, Ofer Saphier, Shai Ayal, Yossef Atiya
• Inventors: ELBAZ, Gilad, LAMPERT, Erez, ATIYA, Yossef, KOPELMAN, Avi, SAPHIER, Ofer, MOSHE, Maayan, AYAL, Shai
• Granted Patent: US 10,380,212 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 1/24 for the mouth, i.e. stomatoscopes, e.g. with tongue depressors tongue depressors per se A61B13/00; Instruments for opening or keeping open the mouth combined with saliva removers A61C17/00; mouth openers for animals A61D15/00
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0062 Arrangements for scanning
• CPC Class Codes: A61B 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7435 Displaying user selection data, e.g. icons in a graphical user interface
• CPC Class Codes: A61C 1/088 Illuminating devices or attachments for examination of the mouth A61B1/24 and A61B1/06
• 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 16/9535 Search customisation based on user profiles and personalisation
• CPC Class Codes: G06Q 50/01 Social networking
• CPC Class Codes: G06T 15/08 Volume rendering
• CPC Class Codes: G06T 17/00 Three dimensional [3D] modelling, e.g. data description of 3D objects
• CPC Class Codes: G06T 2207/30036 Dental; Teeth
• CPC Class Codes: G06T 2207/30244 Camera pose
• CPC Class Codes: G06T 2210/41 Medical
• CPC Class Codes: G06T 7/55 from multiple images
• CPC Class Codes: G06T 7/75 involving models
• CPC Class Codes: H04N 13/221 using the relative movement between cameras and objects
• CPC Class Codes: H04N 13/246 Calibration of cameras
• CPC Class Codes: H04N 13/254 : in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/257 : Colour aspects
• CPC Class Codes: H04N 13/271 : wherein the generated image signals comprise depth maps or disparity maps

Abstract

Methods and apparatuses for generating a model of a subject'"'"'s teeth. Described herein are intraoral scanning methods and apparatuses for generating a three-dimensional model of a subject'"'"'s intraoral region (e.g., teeth) including both surface features and internal features. These methods and apparatuses may be used for identifying and evaluating lesions, caries and cracks in the teeth. Any of these methods and apparatuses may use minimum scattering coefficients and/or segmentation to form a volumetric model of the teeth.

Claims

1. A method of forming a three-dimensional (3D) volumetric model of a subject'"'"'s teeth, the method comprising the steps of:

taking a plurality of near-infrared (near-IR) images of the subject'"'"'s teeth with a camera sensor, wherein the near-IR lighting for the plurality of near-IR images is projected substantially from a direction of the camera sensor;

receiving location data representing a location of the camera relative to the subject'"'"'s teeth for each of the plurality of near-IR images;

generating, for each point in a volume, an upper bound on a scattering coefficient from the plurality of near-IR images and the location data;

combining the upper bound of scattering coefficients for each point in a volume to form a 3D volumetric model of the subject'"'"'s teeth; and

outputting the 3D volumetric model of the subject'"'"'s teeth.

2. The method of claim 1, wherein outputting comprises forming an iso-surface from the 3D volumetric model of the subject'"'"'s teeth.

3. The method of claim 2, further comprising segmenting the iso-surfaces to form an internal structure corresponding to a structure within the subject'"'"'s teeth.

4. The method of claim 1, further comprising receiving surface data representing an exterior surface of the subject'"'"'s teeth, wherein the generating step is performed for each point in the volume within the exterior surface of the subject'"'"'s teeth.

5. The method of claim 1, wherein outputting comprises forming an iso-surface corresponding to an interior dentin surface from the 3D volumetric model of the subject'"'"'s teeth.

6. The method of claim 1, wherein the location data comprises position and orientation data of the camera at the time of capturing each of the plurality of near-IR images.

7. The method of claim 1, wherein the location data comprises three numerical coordinates in a three-dimensional space, and pitch, yaw, and roll of the camera.

8. The method of claim 1, wherein generating for each point in the volume the upper bound on the scattering coefficients comprises:

projecting each point of a 3D grid of points corresponding to the volume of the subject'"'"'s teeth onto each of the plurality of near-IR images using a first calibration;

producing a list of intensity values for each projected point;

converting each intensity value on the list of intensity values to a scattering coefficient according to a volume response; and

storing a minimum scattering coefficient value for each grid point from the scattering coefficients.

9. The method of claim 8, wherein the first calibration comprises a fixed pattern noise calibration to calibrate for sensor issues and image ghosts of the camera.

10. The method of claim 8, wherein the first calibration comprises a camera calibration that determines a transformation for the camera that projects known points in space to points on an image.

11. The method of claim 1, further comprising segmenting the plurality of near-IR images to form an internal structure corresponding to a structure within the subject'"'"'s teeth.

12. A method of reconstructing a volumetric structure from a tooth, wherein the tooth is semi-transparent in a range of radiation wavelengths, the method comprising:

receiving, in a processor, a representation of a surface of the tooth in a first coordinate system;

receiving, in the processor, a plurality of images of the tooth taken by a camera in the range of radiation wavelengths, the plurality of images taken with lighting projected substantially from a direction of the camera;

receiving, in the processor, location data representing a location of the camera for each of the plurality of images;

projecting each point of a grid of points corresponding to a volume within the surface of the tooth onto each of the plurality images using a first calibration;

producing a list of intensity values for each projected point;

converting each intensity value on the list of intensity values to a scattering coefficient according to a volume response; and

storing a minimum scattering coefficient for each point into a list of minimum scattering coefficients.

13. The method of claim 12, further comprising outputting an image produced from the list of minimum scattering coefficients.

14. The method of claim 12, wherein the location data comprises position and orientation data of the camera at the time of capturing each of the plurality of images.

15. The method of claim 12, wherein the first calibration comprises a fixed pattern noise calibration to calibrate for sensor issues and image ghosts of the camera.

16. The method of claim 12, wherein the first calibration comprises a camera calibration that determines a transformation for the camera that projects known points in space to points on an image.

17. The method of claim 12, further comprising receiving surface data representing an exterior surface of the subject'"'"'s teeth, wherein the projecting step is performed for each point in the volume within the exterior surface of the subject'"'"'s teeth.

18. The method of claim 12, wherein the grid of points comprises a cubic grid.

19. The method of claim 12, wherein the camera comprises a camera sensor.

20. A non-transitory computing device readable medium having instructions stored thereon for reconstructing a volumetric structure from a tooth that is semi-transparent in a range of radiation wavelengths, wherein the instructions are executable by a processor to cause a computing device to:

receive a representation of a surface of the tooth in a first coordinate system;

receive a plurality of images of the tooth taken by a camera in the range of radiation wavelengths, the plurality of images taken with lighting projected substantially from a direction of the camera;

receive location data representing a location of the camera for each of the plurality of images;

project each point of a grid of points corresponding to a volume of the tooth onto each of the plurality of images using a first calibration;

produce a list of intensity values for each projected point;

convert each intensity value on the list of intensity values to a scattering coefficient according to a volume response; and

store a minimum scattering coefficient for each point from the scattering coefficients; and

output an image produced from the list of minimum scattering coefficients.

21. The device of claim 20, wherein the location data comprises position and orientation data of the camera at the time of capturing each of the plurality of near-infrared images.

22. The device of claim 20, wherein the location data comprises three numerical coordinates in a three-dimensional space, and pitch, yaw, and roll of the camera.

23. The device of claim 20, wherein the first calibration comprises a fixed pattern noise calibration to calibrate for sensor issues and image ghosts of the camera.

24. The device of claim 20, wherein the first calibration comprises a camera calibration that determines a transformation for the camera that projects known points in space to points on an image.

25. The device of claim 20, wherein the grid of points are inside the tooth.

26. The device of claim 20, wherein the grid of points comprises a cubic grid.