A Fast and Robust Scan-Line Search Algorithm for Object-to-lmage Projection of Airborne Pushbroom Images.

The projection of a 3D object point onto a 2D image plane (i.e., the object-to-image projection) is one of the fundamental operations in photogrammetric data processing. Unlike that for a frame image, the object-to-image projection for a pushbroom image is not a straightforward process because each scan line is exposed at a distinct instant of time, and a preliminary step is therefore required to determine the corresponding scan-line coordinate of the ground point to be projected. This paper presents a new scan-line search algorithm for the object-to-image projection of airborne pushbroom images, which employs a coarse-to-fine strategy following four consecutive steps: affine transformation, iterative search, sequential search, and sub-pixel interpolation. The experimental results with 255 pushbroom images captured in various flight conditions show that the proposed algorithm is robust and can save at least 15 percent of the computational time when compared to the previous methods, while the latter often cannot yield correct results in strong turbulence scenarios. [ABSTRACT FROM AUTHOR]