A Fast Approach to Best Scanline Search of Airborne Linear Pushbroom Images

Abstract

The linear pushbroom camera has become one of the most important imaging sensors in today's photogrammetry and remote sensing practices. Airborne digital sensors (ADS) or three-line scanner (TLS) imaging system such as the ADS40 from Leica Geosystems and STARIMAGER from STAR-LABO Corporation use the pushbroom technique to collect high-resolution, multi-channel seamless image strips. As we know, the object-to-image coordinate computation serves as a core step during the process of photogrammetric images. However, each scanline captured by a linear pushbroom sensor has six exterior orientation ( E O) parameters at the corresponding instant of exposure. The image point coordinates will not be accurately calculated through colinearity equations unless reasonable EO parameters are determined. Therefore, the best scanline search (BSS) has direct effects on efficiency of object-to-image coordinate computation during image processing. This paper addresses a fast BSS method based on the novel central perspective plane of scanline (CPPS) constraints. The search process is simply performed through analytical geometric calculations, which can significantly improve the efficiency of the object-to-image coordinate computation. The feasibility and robustness of the proposed method have been verified using ADS40 and STARIMAGER images. Experimental results show that the proposed method improves scanline search speed considerably with the time cost decreased by nearly 85 percent compared with the traditional methods.