Toward a target-free calibration of a multimodal structured light and thermal imaging system

Abstract

Current calibration methods for multimodal systems consisting of structured light and thermography use calibration targets with physical characteristics. However, defects in the manufacturing of these targets are common. Therefore, these methods are prone to undesired errors. We propose a calibration method for a multimodal system (a visible camera, projector, and thermal imaging camera) that does not require the construction of a physical calibration target. For this purpose, thanks to an auxiliary camera, we use a digital screen to obtain the intrinsic parameters of the camera, and a mirror to obtain the intrinsic and extrinsic parameters of the projector and the thermal imaging camera. The experimental results demonstrate that it is possible to elude the challenging task of fabricating physical targets without compromising the accuracy of the system calibration compared to conventional methods.