Geometrically Corrected 50 Megapixel Thermal Imaging with Full Radiometric Information

Abstract

Thermal imaging has become a valuable method for quality control, damage detection and the identification of energy losses. As in every other method, the resolution is crucial for the outcome of analyses and experiments. State of the art thermography cameras have sensors with 1024 $$\times $$ 768 pixels, which can record thermal images up to 3.1 megapixels via sensor motion and interpolation. Being mobile devices, these cameras cost several ten thousand euros. In this article, we use a comparably cheap 640 $$\times $$ 512 pixel thermography camera for stationary applications, in combination with a panorama head, to create geometrically corrected thermal images of around 50 megapixels with full radiometric information. The panorama head is an optical pivotal point adapter, which can rotate a mounted camera to previously defined angular positions and record images automatically. These single images get geometrically corrected and combined to a whole picture. The technique presented in this article can be applied to almost every thermography camera and is therefore flexible in respect to particular applications or experimental questions. With a novel method of data treatment, the complete radiometric information can be maintained, allowing for a better analysis and processing in thermographic software. With this technique, even full 360 $$^\circ $$ $$\times $$ 180 $$^\circ $$ thermal image panoramas are possible, which can be used for the inventory of buildings. Due to the geometric calibration, these pictures can be combined with dimensionally stable measurements such as e.g. 3D point clouds from laser scanning.