Video-based auto-capture for dental surface imaging apparatus

1. A method for obtaining a contour image of a tooth, the method executed at least in part by a computer and comprising:

detecting movement of an intra-oral camera using video images from a video imaging system in the intra-oral camera by:

(i) acquiring a first video image frame that includes the tooth and processing the first video image frame to detect one or more edges of the tooth in the first video image frame;

(ii) acquiring a second video image frame that includes the tooth and processing the second video image frame to detect the one or more edges of the tooth in the second video image frame;

(iii) comparing corresponding edge locations between the first and second processed video image frames;

and

projecting a fringe pattern illumination onto the tooth from the camera and capturing and storing one or more still images of the fringe pattern when the detected camera movement is below a prescribed threshold.

2. The method of claim 1 wherein comparing corresponding edge locations comprises using a chamfer matching process.

3. The method of claim 1 further comprising displaying the captured one or more still images.

4. The method of claim 1 further comprising shifting the position of the projected fringe pattern illumination along the tooth surface and repeating the step of projecting the fringe pattern illumination and capturing and storing the one or more still images of the fringe pattern according to the detected camera movement.

5. The method of claim 1 further comprising forming and displaying a three-dimensional image of the tooth surface using the one or more still images of the fringe pattern.

6. The method of claim 1 further comprising accepting an operator instruction to project, capture, and store the one or more still images automatically.

7. The method of claim 1 further comprising the step of calculating what fringe pattern images are needed and automatically determining intra-oral camera position and capturing projection pattern images as the camera position is changed.

8. The method of claim 1 wherein the first video frame is temporally adjacent to the second video frame.

9. The method of claim 1 wherein comparing corresponding edge locations comprises scaling the first and second processed video image frames.

10. The method of claim 1 wherein the fringe pattern illumination includes laser light.

11. The method of claim 1 wherein comparing corresponding edge locations comprises computing at least one Euclidean distance value.

12. A method for obtaining a contour image of a tooth, the method executed at least in part by a computer and comprising:

detecting intra-oral camera movement by:

(i) acquiring a first video image frame that shows the tooth and processing the first video image frame to detect one or more edges of the tooth;

(ii) acquiring a second video image frame that shows the tooth and processing the second video image frame to detect the one or more edges of the tooth;

(iii) comparing corresponding edge locations between the first and second processed video image frames to output a movement signal;

energizing a laser and projecting a fringe pattern illumination onto the tooth and capturing and storing one or more still images of the projected fringe pattern when the movement signal based on the detected intra-oral camera movement in the first and second processed video image frames indicates that the detected intra oral camera movement is below a prescribed threshold;

and

forming and displaying a three-dimensional image of the tooth surface using the one or more still images of the fringe pattern.

13. The method of claim 12 wherein comparing corresponding edge locations comprises using a chamfer matching process.

14. The method of claim 12 further comprising displaying the captured one or more still images.

15. The method of claim 12 wherein comparing corresponding edge locations comprises scaling the first and second processed video image frames.

16. A apparatus for imaging a tooth comprising: an intra-oral camera that has:

(i) a detector that acquires image data for video images or fringe pattern images of the tooth;

(ii) a switch actuable for enabling contour imaging of the tooth;

(iii) a first illumination source to project light toward the tooth for the video images; and

(iv) a fringe pattern generator that is energizable to scan a laser light beam onto the tooth for contour imaging, when a movement signal indicative of intra oral camera movement indicates that the intra oral camera movement is below a threshold;

a computer that is in signal communication with the intra-oral camera for receiving the image data acquired by the detector and for generating a contour image of the tooth;

a control logic processor, internal to the intra-oral camera or on the computer, wherein the control logic processor analyses video image data to provides the movement signal that is indicative of camera movement relative to the tooth;

and

a display that is in signal communication with the computer for display of the video and contour images.