Optical EngineeringPhotogrammetric calibration and colorization of the SwissRanger SR-3100 3-D range imaging sensor
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Many robotic and industrial systems require 3-D range-sensing capabilities for mapping, localization, navigation, and obstacle avoidance. Laser-scanning systems that mechanically trace a range-sensing beam over a raster or similar pattern can produce highly accurate models but tend to be bulky and slow when acquiring a significant field of view at useful resolutions. Stereo cameras can provide video-rate range images over significant fields of view but tend to have difficulty with scenes containing low or confusing textures. A new generation of active light, time-of-flight range sensors use a 2-D array of sensor elements to produce a 3-D range image at video rates. These sensors pose unique calibration challenges, requiring both the usual calibration of lens distortion (intrinsic calibration) and calibration of the time-of-flight range measurement (3-D calibration). We present our application of a photogrammetric calibration approach using inexpensive printed optical targets and off-the-shelf software to solve both intrinsic and range calibrations for the MESA Imaging SwissRanger SR-3100 range imaging sensor. Specific calibration issues stemming from this sensor's correlation of reflectivity with measured range are identified. We further present the integration of this otherwise grayscale 3-D sensor with an optical camera, providing a full-color, video-rate 3-D sensing solution.