Depth matched transfer function of the modified composite pattern structured light illumination method

Abstract

Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/16/2015 Terms of Use: http://spiedl.org/termsDepth matched transfer function of the modified composite pattern structured light illumination method Abstract. The use of structured light illumination techniques for three-dimensional (3-D) data acquisition is, in many cases, limited to stationary objects due to the multiple pattern projections needed for depth analysis. High speed N-pattern projections require synchronization between the camera and the projector and have the added expense of these high speed devices. The composite pattern (CP) method allows multiple structured light patterns to be combined via spatial frequency modulation, thereby enabling measurement and rendering of a 3-D surface model of an object using only a single pattern. The capture speed of a single pattern does not require synchronization and is only limited by the camera speed which is N times less than the N-pattern techniques. When used on partially translucent materials such as human skin, the CP weighting is corrupted thereby degrading the 3-D reconstruction. The method described herein, termed modified CP, extends the CP design with the addition of a stripe encoding pattern to be insensitive to the internal scattering of human skin. This stripe pattern, used in conjunction with a new spatial processing method, allows for less contrast sensitivity, less sensitivity to human skin spatial frequency response and thus higher resolution performance. The resolution performance is experimentally measured based on a measure our group has developed, referred to as the depth matched transfer function. Measurements and practical applications are demonstrated.