Dental scanning system with structured light projection

Patent metadata

Field	Value
Publication number	US-12178685-B2
Application number	US-202418418211-A
Country	US
Kind code	B2
Filing date	Jan 19, 2024
Priority date	Jun 22, 2018
Publication date	Dec 31, 2024
Grant date	Dec 31, 2024

Abstract

A dental scanning system comprises an intraoral scanner and one or more processors. The intraoral scanner comprises one or more light projectors configured to project a pattern (comprising a plurality of pattern features) on a dental object, and two or more cameras configured to acquire sets of images, each comprising at least one image from each camera. The processor(s) are configured to determine a correspondence between pattern features in the pattern of light and image features in each set of images by determining intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features in three-dimensional (3D) space based on calibration data that associates the camera rays corresponding to pixels on the camera sensor of each of the two or more cameras to the projector rays.

First claim

What is claimed is:

1. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising:
a handheld intraoral scanner comprising:
one or more light projectors configured to project a uniform pattern of light onto a surface of the dental object, wherein the uniform pattern of light comprises a plurality of pattern features, and wherein each pattern feature of the plurality of pattern features is defined by one or more projector rays; and
two or more cameras configured to acquire one or more sets of images, each of the two or more cameras comprising a camera sensor having an array of pixels, wherein each set of images comprises at least one image from each camera, wherein each image includes one or more image features of at least a portion of the projected uniform pattern of light; and

one or more processors configured to:
for each set of images, determine a correspondence between pattern features in the projected uniform pattern of light and image features in the set of images by determining, in a 3D space, intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data that associates the camera rays corresponding to pixels on the camera sensor of each of the two or more cameras to the projector rays, wherein determining the correspondence comprises:
determining, for a first subset of the pattern features that are associated with a highest number of image features, a first correspondence between the first subset of the pattern features and first image features in the 3D space; and
subsequently determining, for a second subset of the pattern features that are associated with a next highest number of image features, a second correspondence between the second subset of the pattern features and second image features in the 3D space; and

generate the digital 3D representation of the dental object based on the determined correspondence between the pattern features and the image features in the one or more sets of images.

2. The dental scanning system of claim 1 , wherein each light projector comprises at least one light source configured to generate unpatterned light and a pattern generating optical element configured to receive the unpatterned light and to generate the uniform pattern of light based on propagation of the unpatterned light through the pattern generating optical element.

3. A dental scanning system for generating a digital three-dimensional (3D) representation of a dental object, the dental scanning system comprising:
a handheld intraoral scanner comprising:
one or more light projectors configured to project a checkerboard pattern of light onto a surface of the dental object, wherein each light projector comprises at least one light source configured to generate unpatterned light and a pattern generating optical element configured to receive the unpatterned light and to generate the checkerboard pattern of light based on propagation of the unpatterned light through the pattern generating optical element, wherein the pattern generating optical element comprises a transmission mask, wherein the at least one light source comprises at least one light emitting diode, wherein the checkerboard pattern of light comprises a plurality of pattern features, and wherein each pattern feature of the plurality of pattern features is defined by one or more projector rays; and
two or more cameras configured to acquire one or more sets of images, each of the two or more cameras comprising a camera sensor having an array of pixels, wherein each set of images comprises at least one image from each camera, wherein each image includes one or more image features of at least a portion of the projected checkerboard pattern of light; and

one or more processors configured to:
for each set of images, determine a correspondence between pattern features in the checkerboard pattern of light and image features in the set of images by determining, in a 3D space, intersections of projector rays corresponding to one or more of the plurality of pattern features and camera rays corresponding to the one or more image features based on calibration data that associates the camera rays corresponding to pixels on the camera sensor of each of the two or more cameras to the projector rays, wherein determining the correspondence comprises:
determining, for a first subset of the pattern features that are associated with a highest number of image features, a first correspondence between the first subset of the pattern features and first image features in the 3D space; and
subsequently determining, for a second subset of the pattern features that are associated with a next highest number of image features, a second correspondence between the second subset of the pattern features and second image features in the 3D space; and

generate the digital 3D representation of the dental object based on the determined correspondence between the pattern features and the image features in the one or more sets of images.

4. The dental scanning system of claim 2 , further comprising:
a collimating lens between the at least one light source and the pattern generating optical element.

5. The dental scanning system of claim 1 , wherein:
the one or more light projectors are disposed at a distal end of a probe of the handheld intraoral scanning device and are oriented to face the dental object when the dental object is placed in a field of illumination of the one or more light projectors; and
the two or more cameras are disposed at the distal end of the probe and are oriented to face the dental object when the dental object is placed in a field of view of the two or more cameras.

6. The dental scanning system of claim 1 , wherein the one or more processors are further to:
compute depths for one or more pattern features of the plurality of pattern features by triangulation based on a plurality of images of the one or more sets of images comprising image features corresponding to the one or more pattern features.

7. The dental scanning system of claim 1 , wherein the uniform pattern of light comprises a first unchanging pattern and a second unchanging pattern projected by one light projector of the one or more light projectors.

8. The dental scanning system of claim 1 , wherein the uniform pattern of light comprises a first unchanging pattern projected using first light having a first wavelength and a second unchanging pattern projected using second light having a second wavelength, wherein the first unchanging pattern and the second unchanging pattern are to be projected at a same time.

9. The dental scanning system of claim 1 , wherein the one or more processors are further to:
resolve first image features from second image features in the one or more sets of images prior to determining the correspondence between the pattern features and the image features.

10. The dental scanning system of claim 9 , wherein the first image features are generated by light having a first wavelength and the second image features are generated by light having a second wavelength.

11. The dental scanning system of claim 1 , wherein a total combined field of view of the two or more cameras is between 20 mm and 50 mm along a longitudinal axis of the handheld intraoral scanning device.

12. The dental scanning system of claim 1 , wherein the uniform pattern of light comprises a plurality of spots, and wherein each of the plurality of pattern features and each of the one or more image features corresponds to a spot of the plurality of spo

Assignees

• Align Technology Inc

Inventors

• Saphier Ofer
• Atiya Yossef
• Rudnitsky Arkady
• Makmel Nir
• Ozerov Sergei
• Verker Tal
• Levy Tal

Classifications

• G06T2210/41

  Medical · CPC title

• G06T17/00

  Three-dimensional [3D] modelling for computer graphics · CPC title

• A61B1/00096

  Optical elements · CPC title

• A61B1/00172

  with means for scanning · CPC title

• A61C9/0066

  Depth determination through adaptive focusing · CPC title