# US 2018/0025529 A1 · Apparatus and method of texture mapping for dental 3d scanner

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- Number: US 2018/0025529 A1
- Document ID: US20180025529A1
- Status: Published application
- Kind: A1
- Application number: 15/546,396
- Filed: 2015-09-11
- Published: 2018-01-25
- Earliest claimed: 2015-03-09
- Assignees: Carestream Dental Technology Topco Limited
- Applicants: Carestream Health, Inc.
- Inventors: Yingqian Wu; Victor C. Wong; Qinran Chen; Zhaohua Liu
- Web page: https://patentgrep.com/patent/US20180025529A1

## CPC

- G06T 15/04: Texture mapping
- A61B 5/0088: {for oral or dental tissue}
- A61B 5/1077: {Measuring of profiles}
- G01J 3/501: {Colorimeters using spectrally-selective light sources, e.g. LEDs}
- G01J 3/508: {measuring the colour of teeth}
- G06T 2210/41: Medical
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

A method for color texture imaging of teeth with a monochrome sensor array obtains a 3-D mesh representing a surface contour image according to image data from views of the teeth. For each view, recording image data generates sets of at least three monochromatic shading images. Each set of the monochromatic shading images is combined to generate 2-D color shading images, corresponding to one of the views. Each polygonal surface in the mesh is assigned to one of a subset of the views. Polygonal surfaces assigned to the same view are grouped into a texture fragment. Image coordinates for the 3-D mesh surfaces in each texture fragment are determined from projection of vertices onto the view associated with the texture fragment. The 3-D mesh is rendered with texture values in the 2-D color shading images corresponding to each texture fragment to generate a color texture surface contour image.

## Claims

### Claim 1

A method for color texture mapping to a 3-D contour image of one or more teeth in an intra-oral camera with a monochrome sensor array, comprising:
obtaining a 3-D mesh representing a 3-D surface contour image of the one or more teeth according to image data recorded from a plurality of views of the one or more teeth, wherein for each of the plurality of views, recording image data comprises generating a plurality of sets of at least three monochromatic shading images by projecting light of at least three different spectral bands onto the one or more teeth and recording the corresponding image data on the monochrome sensor array;
combining each set of the at least three monochromatic shading images to generate a plurality of 2-D color shading images, where each of the plurality of 2-D color shading images corresponds to one of the plurality of views;
assigning each polygonal surface in the 3-D mesh representing the 3-D surface contour image of the one or more teeth to one of a subset of the plurality of views;
grouping 3-D mesh polygonal surfaces assigned to the same view into a texture fragment;
determining image coordinates for vertices of the 3-D mesh polygonal surfaces in each texture fragment from projection of the vertices onto the view associated with the texture fragment; and
rendering the 3-D mesh with texture values in the 2-D color shading images corresponding to each texture fragment according to the determined image coordinates to generate a color texture 3-D surface contour image of the one or more teeth.

### Claim 2 (depends on 1)

The method of claim 1, where assigning each 3-D mesh polygonal surface forming the 3-D surface contour image of the one or more teeth to said one of a subset of the plurality of views comprises:
identifying 3-D mesh polygonal surfaces forming the 3-D surface contour image of the one or more teeth; and
matching each 3-D mesh polygonal surface to a view with the closest orientation alignment.

### Claim 3 (depends on 1)

The method of claim 1, further comprising storing, transmitting, or displaying the generated color texture 3-D surface contour image of the one or more teeth.

### Claim 4 (depends on 1)

The method of claim 1, further comprising
generating a global texture map for all regions in the 2-D color shading images corresponding to each texture fragment; and
storing, transmitting, or displaying any of:
(i) the 3-D mesh representing the 3-D surface contour image of the one or more teeth,
(ii) the image coordinates associated with vertices of the 3-D mesh polygonal surfaces in each texture fragment, and
(iii) the global texture map.

### Claim 5 (depends on 4)

The method of claim 4, where the global texture map is a reduced-size representation of portions of the 2-D texture shading images correlated to the texture fragments, and is used for rendering of the color texture 3-D surface contour image of the one or more teeth.

### Claim 6 (depends on 1)

The method of claim 1, further comprising smoothing boundaries between adjacent texture fragment surfaces according to texture values.

### Claim 7 (depends on 1)

The method of claim 1, where combining each set of the at least three monochromatic shading images comprises:
registering individual ones of the each set of the at least three monochromatic shading images to each other; and
combining data from the registered set of the at least three monochromatic shading images to generate one color shading image having a single view of the one or more teeth.

### Claim 8 (depends on 7)

The method of claim 7, where said registering the at least three monochromatic shading images to each other comprises 2-D feature extraction and transformations between the at least three monochromatic shading images.

### Claim 9 (depends on 1)

The method of claim 1, where obtaining the 3-D mesh representing the 3-D surface contour image of the one or more teeth comprises: generating the 3-D mesh according to recorded image data from structured pattern projection onto the one or more teeth.

### Claim 10 (depends on 9)

The method of claim 9, where the generating surface contour image comprises, for each of a plurality of structured patterns, projecting the structured pattern onto the one or more teeth and recording image data from the structured pattern onto a monochrome sensor array, where said projecting the structured pattern is performed when the intra-oral camera is moving or still, wherein the plurality of structured patterns include shifted versions of a pattern having multiple lines of light, where projecting the structured pattern comprises energizing a digital micromirror array or energizing a liquid crystal device.

### Claim 11 (depends on 1)

The method of claim 1, where generating at least three monochromatic shading images comprises:
projecting light of a first spectral band onto the one or more teeth and recording a first color component image data on the monochrome sensor array;
projecting light of a second spectral band onto the one or more teeth and recording a second color component image data on the monochrome sensor array; and
projecting light of a third spectral band onto the one or more teeth and recording a third color component image data on the monochrome sensor array,
where said projecting the projecting light and recording color component image data is performed when the intra-oral camera is moving or still.

### Claim 12 (depends on 11)

The method of claim 11, where said combining each set of the at least three monochromatic shading images comprises combining the recorded first, second, and third color component image data for each image pixel with color calibration data to generate a set of color values for the pixel, where said color calibration data is a prescribed color linear calibration matrix.

### Claim 13 (depends on 12)

The method of claim 12, further comprising projecting a structured pattern at a first power level and projecting the light of at least one spectral band at a second power level that differs from the first power level.

### Claim 14 (depends on 12)

The method of claim 12, wherein projecting the structured pattern comprises projecting polarized light of the first spectral band onto the one or more teeth or wherein projecting light of the first spectral band onto the one or more teeth and recording first color component image data comprises projecting non-polarized light.

### Claim 15 (depends on 1)

The method of claim 1, where rendering comprises displaying at least a portion of the generated color texture 3-D surface contour image of the one or more teeth.

### Claim 16 (depends on 1)

The method of claim 1 further comprising blending color values in the 2-D color shading images corresponding to each texture fragment.

### Claim 17 (depends on 16)

The method of claim 16, further comprising calculating color difference along all edges of each texture fragment as a boundary condition and calculating an interpolated color difference for all pixels within each texture fragment, and applying the interpolated color difference to pixels within each texture fragment as a blended version of the original color shading image.

### Claim 18

A method for rendering a 3-D surface contour color image of a tooth, the method executed at least in part on a computer system and comprising:
obtaining a 3-D mesh representing a 3-D surface contour image of the tooth as a plurality of polygonal faces according to image data recorded from a plurality of views of the tooth;
identifying a contour image view pose for rendering the surface contour image using the 3-D mesh;
obtaining a set having a plurality of 2-D color shading images, wherein each 2-D color shading image has a corresponding 2-D view pose and is formed by combining a first monochromatic image having illumination of a first spectral band, a second monochromatic image having illumination of a second spectral band, and a third monochromatic image having illumination of a third spectral band;
wherein the first, second, and third monochromatic images for each 2-D color shading image in the set are acquired at the same corresponding 2-D view pose and acquired on a monochromatic sensor array, and when the first, second, and third spectral bands are substantially non-overlapping; and
rendering the 3-D surface contour color image according to an association that relates each of the polygonal faces of the 3-D mesh at the contour image view pose to one of the set of 2-D color shading images.

### Claim 19 (depends on 18)

The method of claim 18, wherein rendering the 3-D surface contour image further comprises, for each polygonal face of the 3-D mesh, mapping a portion of the 2-D color shading image to the corresponding polygonal face that is defined by mapping feature points that define the polygonal face in the 3-D mesh to corresponding pixels in the associated 2-D color shading image.

### Claim 20 (depends on 18)

The method of claim 18, wherein first and second adjacent polygonal faces of the 3-D mesh are respectively associated with two different members of the set of 2-D color shading images.