Methods and apparatuses for forming a three-dimensional volumetric model of a subject's teeth

• US 10,380,212 B2
• Filed: 07/27/2017
• Issued: 08/13/2019
• Est. Priority Date: 07/27/2016
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Elbaz, Gilad, Lampert, Erez, Atiya, Yossef, Kopelman, Avi, Saphier, Ofer, Moshe, Maayan, Ayal, Shai
• Primary Examiner(s): Matt, Marnie A
• Application Number:
  US15/662,250
• Publication Number:
  US 20180028064A1
• Time in Patent Office: 747 Days
• Field of Search: 348 45
• 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 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 digital representation of a surface of the tooth, 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, and location data representing a location of the camera for each of the plurality of images;

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

producing a list of intensity values for each projected point;

converting the intensity values on the list of intensity values into scattering coefficients according to a volume response; and

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

outputting a volumetric model of the tooth produced from the list of minimum scattering coefficients.

2. 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 images.

3. The method of claim 1, wherein the first calibration comprises a fixed pattern noise calibration to calibrate for sensor issues and image ghosts of the camera.

4. The method of claim 1, 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.

5. The method of claim 1, wherein receiving the digital representation of the surface of the subject'"'"'s tooth comprises determining the digital representation of the surface of the subject'"'"'s tooth from a second plurality of images of the tooth taken in a visible-light range of radiation wavelengths taken from approximately the same locations as the plurality of locations of images of the tooth taken by the camera in the range of radiation wavelengths, further wherein projecting the plurality of points is performed for each point in the volume.

6. The method of claim 1, wherein the grid of points comprises a cubic grid.

7. The method of claim 1, wherein the camera comprises a camera sensor.

8. The method of claim 1, wherein the range of radiation wavelengths comprises a near-infrared (near-IR) range of wavelengths.

9. 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 digital representation of a surface of the tooth in a first coordinate system, 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, and location data representing a location of the camera for each of the plurality of images;

project a plurality of points of a grid of points corresponding to a volume of the tooth onto each of the plurality of images using a first calibration, wherein the grid of points are inside the tooth;

produce a list of intensity values for each projected point;

convert the intensity values on the list of intensity values to scattering coefficients according to a volume response; and

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

output a volumetric model of the tooth produced from the list of minimum scattering coefficients.

10. The device of claim 9, 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.

11. The device of claim 9, wherein the location data comprises three numerical coordinates in a three-dimensional space, and pitch, yaw, and roll of the camera.

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

13. The device of claim 9, 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.

14. The device of claim 9, wherein the grid of points comprises a cubic grid.

15. The method of claim 9, wherein the range of radiation wavelengths comprises a near-infrared (near-IR) range of wavelengths.

16. A method of reconstructing a volumetric structure from a tooth, wherein the tooth is semi-transparent in a range of infrared (IR) radiation wavelengths, the method comprising:

collecting, in a processor, a digital representation of a surface of the tooth, a plurality of images of the tooth taken by a camera in the infrared range of radiation wavelengths, and location data representing a location of the camera corresponding to each of the plurality of images;

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

producing a list of intensity values derived from the plurality of images for each projected point;

converting the intensity values of the list of intensity values to scattering coefficients according to a volume response; and

storing a minimum scattering coefficient for each point; and

outputting a volumetric model of the tooth produced from the minimum scattering coefficients.

17. The method of claim 16, wherein the location data comprises position and orientation data of the camera at the time of capturing each of the plurality of images.

18. The method of claim 16, 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.

19. The method of claim 16, wherein collecting comprises determining the digital representation of the surface of the subject'"'"'s tooth from a second plurality of images of the tooth taken in a visible-light range of radiation wavelengths, wherein second plurality of images are taken from approximately the same locations as the plurality of images of the tooth taken by the camera in the infrared range of radiation wavelengths.

20. The method of claim 16, wherein the grid of points comprises a cubic grid.

21. The method of claim 16, wherein the range of infrared (IR) radiation wavelengths comprises near-IR radiation wavelengths.