Infrared camera calibration for dense depth map construction

In this paper, we introduce a novel and cost effective approach to calibrate the geometric properties of a far-infrared (IR) sensor. We further demonstrate that fully automatic sensor-to-sensor calibration is feasible in a setup involving a laser range scanner, IR cameras as well as conventional cameras. The calibration result then serves as a basis for upsampling range measurements to the resolution of the IR or visible-light camera images. Since our approach allows to rely on IR information instead of visible-light information for upsampling, bad light conditions or even no visible light at all are no limitation. From a practical point of view, we only require one calibration board of relatively small size which facilitates application in outdoor environments and further allows seamless integration of the IR camera in an existing multi-sensor platform. Our experimental results demonstrate that IR images are particularly useful to obtain reasonable depth information for living objects, when visible-light cameras are either blind or require impractical exposure times. In fact, our approach provides a convenient solution to IR camera calibration and integration, an issue which is particularly important in scenarios where sensors are not permanently mounted on vehicles and consequently require on-site adjustment and calibration.