Effect of Rectification mode on Positioning Accuracy of Quickbird panchromatic Image in Loess Hilly and Gully Area

摘要

The high spatial resolution imagery have been used in extensive scopes in recent years, however the effect of different rectification modes on positioning accuracy of those imagery has not been validated by tests. In this article, we took one Quickbird panchromatic image of the Loess hilly and gully area of North Shaanxi province as an example to carry out corresponding tests. In the tests, four rectification modes were designed: polynomial transformation and orthorectification with reference of points measured by GPS in the field; polynomial transformation and orthorectification with reference of rectified 1:10000 topographic maps. The tests come to the conclusions as follows. (1) Before the rectification, the positioning accuracy of Quickbird panchromatic image is between the range of 90 to 160 meters; (2) With the different numbers of GCPs evenly distributed, the scopes of total RMS error of GCPs are larger than that of RMS error of positioning accuracies of rectified images in each rectification mode; (3) Among those four modes, the positioning accuracy of Quickbird panchromatic image through GPS points - orthorectification mode is highest, and the 1:10 000 map - orthorectification mode comes second, and the GPS points- polynomial transformation comes third, and 1:10000 map- polynomial transformation is lowest, and the highest values are 2.33 meters, 4.30 meters, 6.91 meters and 7.42 meters respectively. In the four modes, only in the GCP points- orthorectification mode, the GCP number has little effect on the positioning accuracies of rectified images. In other three modes, with the GCP number decreases, the accuracy of rectified images decreases.