Compound structured light projection system for 3-D surface profiling

摘要

A method and apparatus is provided for high speed, non-contact method of measuring the 3-D coordinates of a dense grid of points on a surface, including high accuracy interpolation between grid points. A plurality of pulsed laser sub-projectors sequentially illuminates a plurality of discrete Gray code bar pattern transparencies carried on a spinning circular code disk to project high frame rate structured light. The structured light is reflected by the surface and recorded at high signal-to-noise ratio by a plurality of high frame rate digital cameras, then decoded and interpolated by electronic signal processing. A numerical formula is derived for numbers of equally spaced discrete code patterns on the code disk that allow each camera to receive pulses from all sub-projectors and all patterns at a constant frame rate. Methods to derive an extended complementary Gray code pattern sequence and to normalize measured signal amplitudes are presented.

主权项

1. A 3-D surface profiling system comprising one or more digital cameras and a compound beam projector apparatus for sequential projection of NSLIDES bar pattern slides equally spaced at a common radius on a flat spinning circular disk rotating at a frequency f_disk, where each said bar pattern consists of a periodic arrangement of alternating clear and opaque rectangles, the long side of the rectangles in each pattern being parallel to each other and perpendicular to a radial line from the center of said disk through the center of said rectangles, with each slide being strobe-illuminated at a constant pulse repetition rate of NSLIDES times f_disk by each of four sub-projectors arranged at said common radius and spaced 90 degrees apart with respect to the center of the disk, the number of equally spaced slides NSLIDES on the disk being defined by the formula NSLIDES=(m×4)+1 where m is an integer, resulting in a constant pulse repetition rate at any point sequentially illuminated by the four sub-projectors.