Direct Georeferencing of SPOT 5 HRS Imagery Without(or with a Few) Ground Control Point

The photographic principle of SPOT 5 HRS is discussed in detail.By a series of coordinate system transforming,the rigorous orbit model of direct geo-referencing without ground control point is established.Experimental results of three datasets show that there are systematic errors existed.Once a ground control point is introduced,the result is improved tremendously.Results of 580 km test dataset with one ground control point are still better than 20 m for the planar position and about 10m for the altitude.It shows that the orbit itself is very stable.The HRS imagery has promising potential for various applications.