1. An apparatus for 3D surface measurement of a target surface, the apparatus comprising: only two projectors, the two projectors comprising, a first projector configured to project a fringe pattern onto the target surface and; a second projector configured to project a fringe pattern onto the target surface; only two cameras, the two cameras comprising, a first camera configured to capture the fringe patterns projected by the first projector and the second projector and; a second camera configured to capture the fringe patterns projected by the first projector and the second projector; wherein the first projector, the second projector, the first camera and the second camera are calibrated with a same global coordinates, wherein the first projector and the first camera form a first optical 3D sensor configured to capture a first fringe pattern, wherein the second projector and the first camera form a second optical 3D sensor configured to capture a second fringe pattern, wherein the first projector and the second camera form a third optical 3D sensor configured to capture a third fringe pattern, and wherein the second projector and the second camera form a fourth optical 3D sensor configured to capture a fourth fringe pattern; and a computer configured to: perform fringe pattern processing of the first fringe pattern to generate a first 3D point cloud, perform fringe pattern processing of the second fringe pattern to generate a second 3D point cloud, perform fringe pattern processing of the third fringe pattern to generate a third 3D point cloud, perform fringe pattern processing of the fourth fringe pattern to generate a fourth 3D point cloud, and perform data stitching and merging of the first 3D point cloud, the second 3D point cloud, the third 3D point cloud, and the fourth 3D point cloud to obtain a 3D surface reconstruction using the calibration with the same global coordinates.