Integrating Stereo Images and Laser Altimeter Data of the ZY3-02 Satellite for Improved Earth Topographic Modeling

Abstract

The positioning accuracy is critical for satellite-based topographic modeling in cases of exterior orientation parameters with high uncertainty and scarce ground control data. The integration of multi-sensor data can help to ensure precision topographical modeling in such situations. Presently, research on the combined processing of optical camera images and laser altimeter data has focused on planetary observations, especially on the Moon and Mars. This study presents an endeavor to establish a combined adjustment model with one constraint in image space for integration of ZY3-02 stereo images and laser altimeter data for improved Earth topographic modeling. The geometric models for stereo images and laser altimeter data were built first, and then, the laser ranging information was introduced to construct a combined adjustment model on the basis of the block adjustment model. One constraint that minimized the back-projection discrepancies in image space was incorporated into the combined adjustment. Datasets in several areas were collected as experimental data for the validation work. Experimental results demonstrated that the inconsistencies between stereo images and laser altimeter data for the ZY3-02 satellite can be reduced, and the elevation accuracy of stereo images can be significantly improved after applying the proposed combined adjustment. Experiments further proved that the improved height accuracy is insensitive to the number and relative position of laser altimeter points (LAPs) in stereo images. Moreover, additional plane control points (PCPs) were incorporated to achieve better planimetric accuracy. Experimental results in the Dengfeng area showed that the adjustment results derived by using LAPs and additional four PCPs were only slightly lower than those for the block adjustment with four ground control points (GCPs). Generally, the proposed approach can effectively improve the quality of Earth topographic model.

WITHDRAWN: Optical Satellite Sensor and Positioning Accuracy Assessment for The Hongqi-H9 Wide-Range Satellite in Different Terrains

“…Consequently, applying multi-lens stitching may significantly increase the difference in the pixel resolution between the edge and center of the image plane [13]. Moreover, the shift differences in the images caused by the curvature and rotation of the Earth, among other factors, may lead to different sampling effects at different viewing positions, leading to a deteriorated image quality [14]. The Hongqi-H9 satellite avoids the projection distortion caused by multiple lenses by using a single lens whose optical axis points to the center of the Earth.…”

Laser Spot Center Location Method for Chinese Spaceborne GF-7 Footprint Camera

“…Due to the base-to-height ratio, platform stability, and other factors, the vertical accuracy of optical stereoscopic mapping is difficult to meet application requirements [2]. As a high-precision ranging instrument, laser altimeters can obtain high-precision vertical measurement information, and have been widely used in the field of aerospace photogrammetry [3]; these include the Geoscience Laser Altimetry System (GLAS) system [4], the Mars Orbiter Laser Altimeter (MOLA) system [5], China's ZY3-02 satellite system [6], and Gaofen-7 (GF-7) satellite system. Xie et al [7] verified that the laser precision of the ZY3-02 satellite system is about 2~3 m in areas with a slope less than 2 • , and the absolute accuracy is better than 1 m in flat areas after calibration.…”

“…Xie et al [7] verified that the laser precision of the ZY3-02 satellite system is about 2~3 m in areas with a slope less than 2 • , and the absolute accuracy is better than 1 m in flat areas after calibration. Consequently, integrating the stereo imagery and laser altimeter data has the potential to generate better geometrical positioning accuracy [3], especially for areas where it is difficult to obtain ground control points. However, due to various errors, such as attitude errors, synchronization errors, calibration errors, and environmental errors, the calculated laser ground points may be inconsistent with the real locations.…”

“…However, due to various errors, such as attitude errors, synchronization errors, calibration errors, and environmental errors, the calculated laser ground points may be inconsistent with the real locations. Thus, non-conjugated points are generated by back-projecting the laser ground points to the stereo images [3]. These deviations have caused great difficulties in constructing a combined adjustment model of laser data and stereo image data.…”

Method for the Automatic Generation and Application of Landmark Control Point Library

“…The third way is the technical scheme commonly used in practical engineering applications. Therefore, in general, ground control points play a very important role in improving the geopositioning accuracy of satellite images [8], [9].…”