Motion compensation in a three dimensional scan

A non-transitory computing device readable medium having instructions that can be executed by a processor to cause a computing device to:

• receive a plurality of three-dimensional (3D) scans of a dentition;
• register a distorted one of the plurality of scans to at least one of a previous scan and a subsequent scan;
• determine whether an amount of movement between the previous scan, the distorted scan, and the subsequent scan is within a registration threshold;
• estimate a first motion trajectory from the previous scan to the subsequent scan based on the registration;
• estimate a second motion trajectory during a scanning time of the distorted scan;
• and
• calculate a corrected scan for the distorted scan by compensating for the motion trajectory during the scanning time of the distorted scan.

A computer implemented method, comprising:

• receiving first data from a three-dimensional (3D) scan of a dentition taken with a 3D scanner in a first reference frame;
• receiving second data from a plurality of two-dimensional (2D) images of the dentition taken during the scan of the dentition with a 2D imager in a second reference frame that is fixed with respect to the first reference frame, where each of the plurality of 2D images is associated with a respective time in the scan;
• determining an optical flow based on local motion between consecutive images of the plurality of 2D images;
• estimating a motion trajectory of a point in the scan;
• improving the estimated motion trajectory using the optical flow to estimate a correctness of the estimated motion trajectory;
• and
• compensating for motion during the scan using the improved estimated motion trajectory;
• where the method is performed by the computer.

A system, comprising:

• a scanning module including:
• an intraoral three dimensional (3D) scanner;
• and
• at least one position tracking device directly coupled to the 3D scanner;
• and
• a processing module coupled to the scanning module to:
• estimate an amount of motion of the 3D scanner during a scan as a rigid body transformation based on input from the at least one position tracking device;
• and
• compensate for the amount of motion by applying an inverse of the rigid body transformation to a plurality of points comprising the scan.