Patent ID: 11961244
Assignee: NANJING UNIVERSITY OF SCIENCE AND TECHNOLOGY
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 0:
1. A high-precision dynamic real-time 360-degree omnidirectional point cloud acquisition method based on fringe projection, comprising the steps of:
step_1: building a quad-camera fringe projection system based on a stereo phase unwrapping (SPU) method, and completing a system calibration;
step_2: obtaining an absolute phase of an object, so as to realize an acquisition of real-time high-precision 3D data under a single viewing angle of the object;
step_3: in a coarse registration thread, using a scale-invariant feature transformation (SIFT) method to obtain 2D matching points of adjacent images, and realizing the coarse registration based on a simultaneous localization and mapping (SLAM) technology by solving a “perspective n-point” (PnP) problem, and at the same time quantifying an amount of motion of the object during each coarse registration; and
step_4: in a fine registration thread, in response to an accumulated motion amount of the coarse registration reaching a threshold, performing a fine registration based on a closest point iterative (ICP) method,
wherein the step 2 further comprises the sub-steps of:
projecting, by a projector, three-step phase-shifting fringe patterns to the object and simultaneously capturing three-step phase-shifting fringe images by using a plurality of cameras;
obtaining a wrapped phase of the object from three-step phase-shifting fringe images captured by a first camera of the plurality of cameras; and
obtaining the absolute phase of the object only through three-step phase-shifting fringe images captured by the plurality of cameras,

wherein the step 3 further comprises the sub-steps of:
finding the 2D matching points of the adjacent images by assuming two adjacent 3D frames;
optimizing the 2D matching points by using 3D information;
obtaining rotation and translation matrices between adjacent 3D frames; and
quantifying an amount of motion in each coarse registration, and

wherein the step 4 further comprises the sub-steps of:
comparing a cumulative motion of coarse registration and a size of a motion threshold to determine whether the fine registration can be performed; and
performing the fine registration.