3-D Scanner Calibration with Active Display Target Device

• US 20190000412A1
• Filed: 12/08/2015
• Published: 01/03/2019
• Est. Priority Date: 12/08/2015
• Status: Active Grant

• Current Assignee: Dental Imaging Technologies Corporation (Envista Holdings Corporation)
• Original Assignee: Carestream Dental Technology Topco Limited
• Inventors: Wong, Victor, Fan, Chuanmao
• Granted Patent: US 11,484,282 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 6/022 Stereoscopic imaging
• CPC Class Codes: A61B 6/512 Intraoral means
• CPC Class Codes: A61B 6/584 determining position of components of the apparatus or device using images of the phantom
• CPC Class Codes: A61C 9/006 projecting one or more stripes or patterns on the teeth
• CPC Class Codes: G01B 11/2504 Calibration devices
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 11/2518 Projection by scanning of the object

Abstract

Exemplary method and apparatus embodiments according to the applications can provide calibration of a dental scanning device. An exemplary dental apparatus can include a sensing apparatus including at least one lens and a sensor that is configured to obtain one or more images of at least one surface position, and a calibration target including a spatial light modulator configured to form a prescribed set of calibration patterns, and whose display plane corresponds to the at least one surface position.

Claims

1. A dental imaging apparatus for surface contour imaging of an object, the apparatus comprising:

a first sensing apparatus comprising at least one lens and a sensor that is configured to obtain one or more images of at least one surface position; and

a calibration target comprising a spatial light modulator configured to form a prescribed set of calibration patterns, and whose display plane corresponds to the at least one surface position.

2. The dental imaging apparatus of claim 1, where obtained images of the calibration patterns by the first sensing apparatus are decoded to determine a dense one-to-one correspondence between the image points on the first sensing apparatus and on the calibration target.

3. The dental imaging apparatus of claim 1, where the spatial light modulator is an LCD display target device or an active display target device.

4. The dental imaging apparatus of claim 1, further comprising a second sensing apparatus comprising at least one lens and a sensor that is configured to obtain one or more images of the at least one surface position from a different angle than the first sensing apparatus.

5. The dental imaging apparatus of claim 1, further comprising an illumination apparatus configured to direct one or more illumination patterns toward the at least one surface position.

6. The dental imaging apparatus of claim 5, where illumination patterns are directed before or after the displaying of the prescribed set of calibration patterns, where obtained images of the illumination patterns and calibration patterns by the first sensing apparatus are decoded to determine a one-to-one correspondence between the image points on the illumination apparatus and points on the calibration target.

7. The dental imaging apparatus of claim 1, where an active display target device is the calibration target that is used for calibration of single camera system, stereo vision system, multi-view vision system, or projector-camera system.

8. The dental imaging apparatus of claim 1, where the calibration target comprises a flat surface with a planarity better than approximately 10 microns.

9. The dental imaging apparatus of claim 1, where the prescribed set of calibration patterns include gray codes, checker board patterns, and line shifting.

10. The apparatus of claim 1, where the calibration target is detachably coupled to the dental imaging apparatus and adapted to be movable to positions including at least the surface position.

11. The apparatus of claim 1, where the calibration target is movably housed within a calibration target fixture, and where the calibration target fixture is keyed to detachably couple to the dental imaging apparatus in a predetermined orientation to the first sensing apparatus.

12. The apparatus of claim 11, where the calibration target fixture provides an adjustment configured to change a distance and orientation between the calibration target and the first sensing apparatus.

13. A method for calibration of a dental scanning device, the method comprising:

(a) positioning a calibration target at a position relative to the dental scanning device, where the calibration target comprises a spatial light modulator configured to form a prescribed set of calibration patterns;

(b) acquiring at least one image of the calibration target as the calibration target displays the prescribed set of calibration patterns that code the pixels of the spatial light modulator;

(c) determining a coordinate correspondence between the 2D coordinates of the calibration target coordinate and 2D coordinates of the scanning device; and

(d) determining calibration parameters for the dental scanning device according to the determined coordinate correspondence.

14. The method of claim 13, where acquiring at least one image of the calibration target is performed for more than one pose of the calibration target.

15. The method of claim 13, further comprising updating calibration data for the dental scanning device according to the determined calibration parameters.

16. The method of claim 13, where the dental scanning device is a pair of two cameras providing stereo vision of the calibration target, where the two cameras take images simultaneously and each camera of the two cameras is calibrated independently.

17. The method of claim 13, where the dental scanning device is a dental intraoral scanner comprising a projector configured to project structured light patterns and a camera positioned to receive contour images of the projected structured light patterns that reflect off the calibration target.