Area precision of the features abstracted from SPOT5 image

Compared to other satellite data, SPOT5 image has obvious advantage in spatial resolution of 2.5 m for panchromatic image satisfied with the demand of land use updating survey at 1: 10,000 scale theoretically. But unfortunately, few studies have been done on area precision of the features. In this paper, one case study was taken in Longxiang section of Zhejiang province in China. A system area precision analysis was performed for the features abstracted from SPOT5 image at 1: 10,000 scale based on the data derived from contemporary aerial survey as true references. Based on antitheses, the area precision was analyzed from the different aspects such as land use type, patch size and combination of land use type. At the same time, the minimum patch area was determined for information extraction from SPOT5 image according to certain precision standard. The results indicate that, on 1:10,000 scale, the patch area precision of each land use type reach about 90% overall, except some upland patches with small area. In fact, for some land use types with frequent conversion, such as residence and construction, the patch average area precision can reach about 95%, the maximum of area precision is about 99%. The study also shows that the bigger the patch area is, the higher the precision can be obtained. Furthermore, it is reliable to extract the patch information of buildings with a high area precision when the changing is between building and other land use types. However, the borderline is unsharp when upland borders upon orchard plot, it is difficult to extract the patch information accurately and the area precision is correspondingly low.