Comments: The disadvantage of this approach is of course that it depends strongly on the precision of r₁ and r₂. These are only known with the range resolution of the SAR, i.e. with a precision of several meters. This limits the achievable height resolution to values of around 100m, although better resolutions are possible with high-resolution airborne systems. Nevertheless, this method has widely been used, especially in extraterrestrial mission. For example, a DEM of the cloud-covered venus was generated using radar-grammetry.