LAUSR

The Gaofen-7 (GF-7) satellite system adds a footprint camera that shares the same optical path as its laser altimeter to ensure consistent spatial referencing between the laser footprint point and the obtained optical images. However, this introduces additional errors between the two different loads while ensuring the geometric relations of the laser altimeter and footprint camera. First, the accuracy and error analyses of the laser altimeter and footprint camera are carried out based on the working mode of the GF-7 satellite laser altimeter and footprint camera in this study. A rigorous sensor model of laser geometric positioning is proposed based on the coupled footprint camera, which is achieved for the geometric correlation of laser spots on the ground and the focal plane of the footprint camera. The satellite laser altimeter simulation platform was used to analyze the various error sources in the geometric positioning of the laser altimeter, and GF-7 satellite data were used to verify the proposed geometric positioning model of the laser altimeter and footprint camera. The results show that the positioning error of the GF-7 footprint camera is less than 5 m (root-mean-square error) relative to the dual-line array image, which can provide ground control points for stereo mapping.