Better optical triangulation through spacetime analysis
ICCV '95 Proceedings of the Fifth International Conference on Computer Vision
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Laser ranging finds its application in a number of fields such as robotics, security and automotive systems. Laser distance measurements are either based on TOF (time of flight) principle or optical triangulation principle. Optical triangulation, with all its limitations, finds its way into a number of low cost robotics solutions, due to its low cost and simplicity. Most triangulation range finders map distance ranges from infinity to a minimum measurable distance, on to a corresponding pixel position of an optical sensor. However, due to the non-linear nature of triangulation mapping, range measurements beyond some target distance have unacceptable accuracies for most applications. Hence it suffces to limit the maximum measurable distance to the required distance rather than infinity. This is possible by adjusting the laser angle with respect to the sensor plane. The minimum measurable range is further reduced as a consequence of this. Due to the non-linearity of the mapping, non-linear accuracy improvements are achieved in this added minimum distance region, even though the accuracy at a given range remains the same. Detailed geometrical analysis of this modified approach is performed. This paper discusses the proposed modified approach on Laser Range Finder (LRF) triangulation, its boundary conditions, parameter dependies and compares it with the conventional approach. A simulation model for the conventional and proposed models is developed using C language for validation before prototyping. The result shows an improvement of 9% for minimum range extension at 3m maximum range.