Geometric Accuracy Analysis Model of the Ziyuan-3 Satellite without GCPs

The ZiYuan-3 satellite (ZY-3) was China's first civilian stereo mapping satellite designed to meet the 1:50 000 scale mapping requirements. We analyzed main error sources influencing the geometric accuracy of the ZY-3 images, and the error propagation rules of these error sources in image production. Accuracy estimation models of ZY-3 images without ground control points (GCPs) were deduced and the theoretical geometric accuracy of ZY-3 images was obtained. Without GCPs, 556 ZY-3 panchromatic nadir images covering 3,500,000 km² of the Chinese mid-west region and 12 ZY-3 stereo image pairs covering 14,000 km 2 around Taiyuan of China were used for planar and vertical accuracy verification, respectively. The experimental results confirmed the correctness of the accuracy estimation model for ZY-3 images. The accuracy results obtained through the model and experiment showed that without GCPs, the geometric accuracy of the ZY-3 images satisfied the Chinese stereo mapping requirements for 1:50 000 scale topographic maps.