Method and system for global registration between 3D scans

A computer-implemented method for global registration between a first point cloud and a second point cloud on an identical spatial scene at two separate instances, comprising:

• obtaining, by a scanning device, the first point cloud and the second point cloy d on the identical spatial scene at the two separate instances;
• extracting, by a processor, a first set of discriminative line-pairs from the first point cloud and a second set of discriminative line-pairs from the second point cloud wherein the discriminative line-pair has high discriminative power compared to a randomly selected line-pair;
• identifying, by the processor, a plurality of matching line-pair groups, each of the matching line-pair groups comprising a first discriminative line-pair selected from the first set of discriminative line-pairs and a second discriminative line-pair selected from the second set of discriminative line-pairs, wherein the first discriminative line-pair and the second discriminative line-pair satisfy:
• at least one thresholding criterion related to between-line relationship, line geometry and line location;
• and
• a compass angle criterion when the first discriminative line-pair is transformed to a reference coordinate by a first transformation matrix and the second discriminative line-pair is transformed to the reference coordinate by a second transformation matrix;
• selecting, by the processor, a best orientation angle for the first point cloud and the second point cloud derived from compass angles for the plurality of matching line-pair groups;
• computing, by the processor, a global transformation matrix based on the best orientation angle, aggregations of respective first transformation matrices and respective second transformation matrices;
• and
• using the global transformation matrix to align the first point cloud and the second point cloud.