Flexible calibration of color and depth camera arrays

Abstract

In this work we present a flexible approach for calibrating an array of multiple stationary color and depth cameras using an optical tracking system. Our application domain is focused on 3D telepresence. Calibrating cameras in this area is still a major problem due to the limited applicability of common calibration approaches. Usually, groups of cameras are calibrated relative to each other by either requiring heavily overlapping fields of view for many pairs of participating cameras or free movable cameras. Our method moves away from these techniques by calibrating every camera individually. The key technology applied is a tracked calibration target with permanently identified global location provided by a tracking device. Detecting the known target geometry in a camera image provides, beside intrinsic calibration parameters, the position of the camera relative to the target. Combining these two aspects of the calibration target’s location makes it possible to register every camera in the common tracking coordinate system. We validate our approach using our prototype with 12 Firewire color cameras, 3 Kinect depth cameras, an OptiTrack tracking device, and a checkerboard with an attached trackable rigid body (see Figure 1). In this setup, we achieve a reprojection error of below 0:5 pixels on average.