3D line reconstruction from airborne three-line scanner data

This paper deals with the automatic reconstruction of 3D object lines from airborne three-line scanner data. These novel sensor systems contain three linear CCD arrays which are oriented perpendicular to the flight direction of the aircraft. In a first processing step, raw image data is projected onto a plane at mean terrain height, resulting in three so-called rectified images with different viewing angles. Although these images are visually equal to frame images, after rectification they still contain small projection errors due to aircraft movements in combination with the line perspective geometry of the sensor. We present a new two-step feature-based approach to extract 3D information from three-line scanner data. In the first step 2D extracted lines are matched in three rectified images. Due to errors in the rectified images and in the 2D line extraction, the matching algorithm only provides approximate 3D information. After the approximate alignment of the object line by the matching algorithm, more precise estimates of pose parameters can be obtained by a least squares fitting algorithm in the second step. In this step the geometry of the recording situation is used in order to remove projection errors. Results of the two-step approach are shown for a complex building model, proving the high potential of airborne digital line scanners for 3D feature extraction purposes.