Block-adjustment with sparse GCPs and SPOT-5 HRS imagery for the Project of West China Topographic Mapping at 1:50,000 scale

High-resolution satellite images (HRSI) at sub-5m footprint such as IKONOS and SPOT-5 HRG/HRS images are becoming increasingly available to the earth observation community and their respective clients. SPOT-5 imagery is one of the main data sources for the project of West China topographic mapping (WChTM) which has been approved by the State Council of China in year 2006. In this paper, we present an approach for block-adjustment based on rational function model (RFM) with sparse GCPs by using SPOT-5 Images. To test the proposed approach, it has been applied to SPOT-5 images over 2 test-fields, one is in Baoji City, Chanxi, China, and another covers eastern part of Tibet Plateau, China. All test-fields are with variable terrain geomorphologic type and several tens of GCPs and check points measured by DGPS. The block-adjustment results show that with SPOT-5 HRS images and small number of GCPs we can achieve 5-9 m in planimetric and 2-3 m in height direction. From these experiments, itpsilas shown that with the proposed block-adjustment approach, by using SPOT-5 HRS imagery with small number of GCPs, satisfactory image orientation results can be achieved with a little bit better accuracy than those requirements from the Chinese surveying and mapping regulations for 1:50000 topographic maps.