Preliminary Evaluation of the Stereo Mapping Accuracy of the Gaofen-7

The Gaofen-7 (GF-7) is China’s new-generation sub-meter stereo mapping satellite and an important part of the CHEOS (China High Resolution Earth Observation System). The stereo mapping camera carried on GF-7 allows acquisition of along-track stereoscopic pairs with a swath width greater than 20 km, a resolution better than 0.8 m, and a base-to-height ratio of approximately 0.6. GF-7 stereo data over Sichuan and Heilongjiang test sites are used for the evaluation and analysis of 1:10,000 scale stereo mapping accuracy. The test results show that, according to China’s mapping specifications, products such as digital line graphic (DLG), digital terrain model (DTM), digital surface model (DSM) and digital orthophoto map (DOM) can meet the accuracy requirements for hilly, mountainous and alpine terrain. For the flat terrain type with the highest accuracy indicators, products such as DTM, DSM and DOM can also achieve the required accuracy; but for the DLG products, the elevation accuracy is not always able to meet the specifications, which need to be further studied.