Generation And Use Of Color Pseudo Random Sequences For Coding Structured Light In Active Ranging

When using structured light for the measurement of three dimensional objects, the observed stripes of light must be indexed, that is, the correspondance between projected light stripes and the observed stripes must be established. Basically, time, spatial and color coding can be used to characterize the light stripes. In this study, we use color coding and generate the projected light stripes as a sequence of colors showing subsequences of length N which are all different and thus can be indexed by analysis of the observed stripe sequence. The sequence generation used follows the methods known for generating pseudo random sequences. We present also several indexing rules and analyse their behaviour in a measurement setup exhibiting stripe deletions and permutations. A parametric method is proposed which can accomodate scenes with different object coarseness.