Orthophoto Creation Based on Low Resolution Thermal Aerial Images

Abstract

The creation of high-resolution thermal images, which cover great areas and which are suitable for area measurements, proves to be a serious challenge. The native resolution of thermal cameras is significantly lower than of cameras operating within the visible light spectrum. Conventional methods, which are capable of producing large, so-called orthophotos from several pictures, cannot be applied for thermal images. However, if specific requirements are met, it is possible to produce an orthophoto from overlapping thermal image mosaics, which contains a larger area. The advantage of the thermal orthophoto is that it displays thermal radiation within the spectrum 7–14 μm, that is invisible to the naked eye, in such manner that the area deemed interesting can be substantially enlarged and distance and area calculation can be conducted on the picture. The developed procedure can be automatized, in this way, this means a process difficulty nearly identical to the creation of orthophotos within the visible light range. During the experiments, an extremely low-resolution (160 * 120 pixel), 35 Megapixel thermal image was created using the data of the thermal sensor, which met other requirements for the orthophoto.