There still has some def iciencies in photogrammetric application with the existing geometric imaging model of radar imagery. In view of this situation the theoretical analysis was made f irstly in this paper. Then several equations were constructed in turn

including Range-Coplanar （R-Cp） equation with explicit function form of image point coordinate

Range-Coplanarity equation in geocentric coordinate system and rigorous positioning model based on R-Cp equation. At last some tests including rigorous positioning were done with spaceborne TerraSAR-X imagery and sparse ground control point. The theory and experiments show that the proposed R-Cp model embody the attributes of image measurement coordinate as photogrammetric observation value

which make it easy to absorb and utilize mature digital photogrammetric theory and methods developed on collinear equation model for optical remote sensing images. For data processing of radar imagery photogrammetry the model can overcome the shortcomings existed in other model and improve the rigor

stability

reliability and eff iciency.