Real-time key view extraction for continuous 3D reconstruction

1. A method for forming a subset comprising a plurality of member 3D contour images, the method executed at least in part on a computer and comprising the steps of:

selecting a first 3D contour image as a member image;

obtaining a candidate 3D contour image;

computing an overlap between the candidate 3D contour image and the first 3D contour image, wherein the step of computing the overlap comprises:

transforming the member image to a first 2D image having a first center, a first normal indicative of a first view angle and a first plane and extending outward from the first center, and a first boundary in the first plane having a first radius extending from the first center;

transforming the candidate image to a second 2D image having a second center, a second normal indicative of a second view angle and a second plane and extending outward from the second center, and a second boundary in the second plane having a second radius extending from the second center;

obtaining a first distance by projecting the first radius onto a line connecting the first center to the second center;

obtaining a second distance by projecting the second radius onto the line connecting the first center to the second center; and

computing the overlap according to the first distance, the second distance, and a third distance between the first and second centers; and

adding the candidate 3D contour image to the subset according to the overlap computation.

2. A method for forming a subset comprising a plurality of member 3D contour images, the method executed at least in part on a computer and comprising the steps of:

selecting a first 3D contour image as a member image;

obtaining a candidate 3D contour image;

computing an overlap between the candidate 3D contour image and the first 3D contour image, wherein the step of computing the overlap comprises:

transforming the member image to a first 2D image having a first center, a first normal indicative of a first view angle and a first plane and extending outward from the first center, and a first boundary in the first plane having a first radius extending from the first center;

transforming the candidate image to a second 2D image having a second center, a second normal indicative of a second view angle and a second plane and extending outward from the second center, and a second boundary in the second plane having a second radius extending from the second center;

obtaining a first distance by projecting the first radius onto a line connecting the first center to the second center;

obtaining a second distance by projecting the second radius onto the line connecting the first center to the second center; and

computing a third distance between the first and second centers; and

adding the candidate 3D contour image to the subset according to the overlap computation;

wherein the overlap is computed as a ratio, wherein a numerator is formed from the sum of the first and second distances minus the third distance and a denominator is formed from the sum of the first and second distances plus the third distance.

3. A method for forming a subset comprising a plurality of member 3D contour images, the method executed at least in part on a computer and comprising the steps of:

selecting a first 3D contour image as a member image;

obtaining a candidate 3D contour image;

transforming the member image to a first 2D image having a first center, a first normal indicative of a first view angle and extending outward from the first center, and a first boundary having a first radius extending from the first center;

transforming the candidate image to a second 2D image having a second center, a second normal indicative of a second view angle and extending outward from the second center, and a second boundary having a second radius extending from the second center;

obtaining a first distance by projecting the first radius onto a line connecting the first center to the second center;

obtaining a second distance by projecting the second radius onto the line connecting the first center to the second center;

computing an overlap according to the first distance, the second distance, and a third distance between the first and second centers; and

adding the candidate 3D contour image to the subset according to the overlap computation.

4. The method of claim 3 , wherein the method further comprises a step of displaying a rendered 3D image that is generated using the subset of 3D contour images.

5. The method of claim 3 , wherein the method further comprises a step of comparing the computed overlap to a predetermined threshold value.

6. The method of claim 3 , wherein the subset is used as a reference to speed up at least one of searching and tracking process in bite registration, online matching, global matching, and post-processing operations during the scanning and 3D reconstruction of a tooth surface.

7. An apparatus for processing 3D contour images comprising:

a video camera that continuously generates 3D contour images of a subject;

a computer that is in signal communication with the video camera and is programmed with instructions for a process comprising a repeated sequence of:

selecting a first 3D contour image obtained from the video camera as a member image;

obtaining a candidate 3D contour image from the video camera;

computing an overlap between the candidate 3D contour image and the first 3D contour image, wherein computing the overlap comprises:

transforming the member image to a first 2D image having a first center, a first normal indicative of a first view angle and extending outward from the first center, and a first boundary having a first radius extending from the first center;

transforming the candidate image to a second 2D image having a second center, a second normal indicative of a second view angle and extending outward from the second center, and a second boundary having a second radius extending from the second center;

obtaining a first distance by projecting the first radius onto a line connecting the first center to the second center;

obtaining a second distance by projecting the second radius onto the line connecting the first center to the second center; and

computing the overlap according to the first distance, the second distance, and a third distance between the first and second centers;

adding the candidate 3D contour image to a subset of 3D images according to the overlap computation; and

displaying a generated 3D contour image that is rendered according to the subset of 3D images.

8. The apparatus of claim 7 , wherein the subset of 3D images is used as a reference to speed up at least one of searching and tracking process in bite registration, online matching, global matching, and post-processing operations during the scanning and 3D reconstruction of a tooth surface.

9. The apparatus of claim 7 , wherein the overlap is computed as a ratio, wherein a numerator is formed from the sum of the first and second distances minus the third distance and a denominator is formed from the sum of the first and second distances plus the third distance.

10. The apparatus of claim 7 , wherein the repeated sequence further comprises comparing the computed overlap to a predetermined threshold value.