3D intraoral measurements using optical multiline method
A method for mapping a sensor pixel array to an illumination pixel array according to a surface forms a group mapping by assigning each pixel to a corresponding group, each group with p adjacent pixels on the illumination array and each ordered set having k groups, by projecting and recording a sequence of group index images. Each group index image has, in at least two of the groups, no illuminated pixels and in fewer than (k−1) groups, from 2 to (p−1) adjacent illuminated pixels. The sequence of group index images uses pixels from each of the k groups. At least p multiline images are projected and recorded, wherein each multiline image projects a line within each group. Lines in the multiline images are correlated according to the group mapping and the correlation stored in memory. Integers k and p are greater than or equal to 3.
1. A method for mapping a sensor pixel array to an illumination pixel array according to a surface, comprising:
forming a group mapping by assigning each pixel in a plurality of pixels on the sensor array to a corresponding group of an ordered set of groups on the illumination pixel array, wherein each group is p adjacent pixels on the illumination pixel array and each ordered set has k groups, by:
recording a sequence of two or more different group index images of a sequence of two or more different group index patterns projected onto the surface, wherein, with respect to each ordered set of k groups, each projected group index pattern has, in at least two of the groups, no illuminated pixels and in fewer than (k−1) groups, has from 2 to (p−1) adjacent illuminated pixels, and wherein the sequence of projected group index patterns uses illuminated pixels from each of the k groups;
recording at least p multiline images of at least p multiline patterns projected onto the surface, wherein each multiline pattern projects a line within each group of p adjacent pixels on the illumination pixel array;
correlating lines in the recorded multiline images with lines in the projected multiline patterns according to the group mapping; and
storing, displaying, or transmitting the correlation, wherein k and p are integers greater than or equal to 3.
2. The method of claim 1 further comprising:
generating surface contour data according to the stored correlation; and
displaying the surface according to the surface contour data.
3. The method of claim 1 wherein forming the group mapping further comprises projecting and recording at least a first and a second block image, wherein each block image has a pattern with a number m contiguous groups of pixels illuminated at the same time and m contiguous groups of pixels de-energized at the same time, and wherein the pattern for the second block image is shifted from the pattern for the first block image by m/2 groups.
4. The method of claim 1 wherein the illumination pixel array is a liquid crystal device or is a digital micromirror array device, where each multiline pattern projects a line of 2- to p−1 pixels within each group of p adjacent pixels on the illumination pixel array.
5. The method of claim 1 where the sequence of two or more group index images comprises k group index images.
6. The method of claim 1 wherein forming the group mapping further comprises obtaining and recording at least one dark field image and at least one flat field image.
7. The method of claim 1 , where less than half the groups in each ordered set of k groups have 2 to (p−1) illuminated pixels.
8. The method of claim 1 wherein the surface is a tooth, where k>p.
9. The method of claim 1 wherein the adjacent illuminated pixels of the group index image include one or more pixels nearest the center of the group.
10. The method of claim 1 further comprising projecting the sequence of two or more group index images and the multiline images at different power levels.
11. A method for mapping a sensor pixel array to an illumination pixel array according to a surface, the method executed at least in part on a computer and comprising:
characterizing the response of the sensor pixel array by projecting and recording a dark image and a flat image;
forming a group mapping by assigning each pixel in a plurality of pixels on the sensor array to a corresponding group of an ordered set of groups, wherein each group is defined by a set of p adjacent pixels on the illumination pixel array and each ordered set has k groups, by:
(a) projecting and recording one group index image at a time from each set, wherein each group index image has from 1 to (p−1) adjacent illuminated pixels, and successively repeating the projection and recording at least k times; and
(b) projecting and recording at least a first and a second block image, wherein each block image has a pattern with k contiguous groups of pixels illuminated at the same time and k contiguous groups of pixels de-energized at the same time, and wherein the pattern for the second block image is shifted from the pattern for the first block image by k/2 groups;
projecting and recording at least p multiline images onto the surface, wherein each multiline image projects a line within each group;
correlating lines in the recorded multiline images with lines in the projected multiline images according to the group mapping; and
storing, displaying, or transmitting the correlation, wherein k and p are integers greater than or equal to 2.
12. The method of claim 11 wherein the surface is a tooth.
13. The method of claim 11 wherein the adjacent illuminated pixels of the group index image include one or more pixels nearest the center of the group.
14. The method of claim 11 further comprising projecting the sequence of two or more group index images and the multiline images at different power levels.
15. The method of claim 11 further comprising:
generating surface contour data according to the stored correlation; and
displaying the surface according to the surface contour data.
16. The method of claim 1 where the sequence of two or more group index images comprises k group index images.
17. The method of claim 1 , where in each of the group index images, each ordered set of k groups has only 1 group with 2 to (p−1) illuminated pixels.
18. The method of claim 1 , where a center to center distance D between groups with illuminated pixels spans p groups.
19. The method of claim 1 , where less than half the groups in each ordered set of k groups 2 to (p−1) illuminated pixels.
20. A method for mapping a sensor pixel array to an illumination pixel array according to a surface, comprising:
forming a group mapping by assigning each pixel in a plurality of pixels on the sensor array to a corresponding group of an ordered set of groups on the illumination pixel array, wherein each group is p adjacent pixels on the illumination pixel array and each ordered set has k groups, by:
projecting a sequence of two or more group index patterns and recording a sequence of two or more group index images, wherein, with respect to each ordered set of k groups, each projected group index pattern has, in at least two of the groups, no illuminated pixels and in fewer than (k−1) groups, has from 1 to (p−1) adjacent illuminated pixels, and wherein the sequence of projected two or more group index patterns uses illuminated pixels from each of the k groups;
projecting at least p multiline patterns onto the surface and recording at least p multiline images, wherein each of the at least p multiline patterns projects a line within each group of p adjacent pixels on the illumination pixel array;
correlating lines in the recorded multiline images with lines in the projected multiline patterns according to the group mapping; and
generating a surface contour image of the surface using the correlated recorded at least p multiline images, wherein k and p are integers greater than or equal to 3.