3D photogrammetry using projected patterns

1. A method for obtaining a 3D model of an object, comprising:

projecting a pattern onto the object from at least first and second positions;

observing the pattern from the first and second positions by capturing an image P of the pattern incident on the object;

capturing an illumination image I of the object from each of the first and second positions, wherein the image I is captured using an imaging system comprising a projection portion and one or more imaging portions;

forming a 3D model of the object for each of the first and second positions by analyzing observed distortions to the pattern P caused by a 3D surface of the object;

using the 3D model in conjunction with each illumination image Ito find a pixel in the illumination image I of the object from the first position that corresponds to a pixel in the illumination image I of the object from the second position, wherein the corresponding pixels are a matched pixel; and

using photogrammetry to determine 3D coordinates for each matched pixel.

2. The method as described in claim 1 wherein the object is a dental item.

3. The method as described in claim 1 wherein the illumination image I is a full illumination image.

4. A non-transitory computer-readable medium having computer-executable instructions for performing the method steps of claim 1 .

5. Apparatus comprising:

an imaging system comprising a projection portion and one or more imaging portions, a processor in communication with the imaging system, and

a computer-readable medium, the computer-readable medium having processor-executable instructions for performing the method steps of claim 1 .

6. A method for obtaining a 3D model of an object, comprising:

projecting a pattern onto the object from at least two positions;

observing the pattern from those positions by capturing at least two images P 1 and P 2 from slightly different offset locations of the pattern incident on the object;

capturing illumination images I 1 and I 2 of the object for each of the at least two positions, wherein the images I 1 and I 2 are captured using an imaging system comprising a projection portion and one or more imaging portions;

forming a 3D model of the object for each position by analyzing observed distortions to the pattern P caused by the 3D surface of the object;

using the 3D model in conjunction with each image I 1 and I 2 to find corresponding pixels between image I 1 and I 2 ; and

using photogrammetry to determine 3D coordinates for each matched pixel.

7. The method as described in claim 6 wherein the object is a dental item.

8. The method as described in claim 5 wherein the illumination image is a full illumination image.

9. A method for obtaining a 3D model of an object, comprising:

projecting a dense laser pattern onto the object;

observing the dense laser pattern and any associated speckle from the position by capturing at least two images P 1 and P 2 from different offset locations of the laser pattern incident on the object, wherein the at least two images P 1 and P 7 are captured using an imaging system comprising a projection portion and one or more imaging portions;

matching equivalent pairs of speckle features between the two images; and

using photogrammetry to determine 3D coordinates for each matched pixel.

10. A non-transitory computer-readable medium having computer-executable instructions for performing the method steps of claim 9 .

11. Apparatus comprising:

an imaging system comprising a projection portion and one or more imaging portions,

a processor in communication with the imaging system, and

a computer-readable medium, the computer-readable medium having processor-executable instructions for performing the method steps of claim 9 .

12. An imaging system, comprising:

an intra-oral digitizer, comprising:

a light source having collimating optics configured to generate a collimated beam of light;

a scanner optically coupled to the light source and configured to scan the collimated beam along at least two axes;

a first optics relay coupled to the scanner and configured to relay the scanned collimated beam of light towards a dental object to be imaged, wherein over a given scanning period the scanned collimated beam of light generates a pattern comprising a set of segments;

a first image sensor;

a second image sensor;

a second optics relay, co-linear to the first optics relay, configured to relay a reflection of the scanned collimated beam toward the first image sensor, wherein over the given scanning period the reflection of the scanned collimated beam on the first image sensor comprises a first modified pattern; and

a third optics relay, co-linear to the first optics relay, configured to relay a reflection of the scanned collimated beam toward the second image sensor, wherein over the given scanning period the reflection of the scanned collimated beam on the first image sensor comprises a second modified pattern; and

a computer coupled to the intra-oral digitizer that (a) uses at least the first and second modified patterns to generate a 3D model of a surface of the dental object, (b) uses the 3D model in conjunction with at least first and second images of the dental object to find matching pixels between the first and second images, and (c) uses photogrammetry to determine 3D coordinates for each matched pixel.