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Terrain Correction of SAR Images Part 4

A short comment only on the "Range Doppler Terrain Correction." As described in Part 1, the SARSIM algorithm takes the DEM and using orbit parameters of the satellite creates a simulated SAR image from this DEM. The simulated and the real SAR image, which will look very similiar, are coregistered. Through this simulation, the displacement for each location in the original landscape, the DEM, is known, so if the simulated SAR image is transformed back into the original DEM -- and the coregistered SAR image along with it -- the pixels of the SAR image will receive their real, geographical location.

The Range Doppler Algorithm does not simulate a SAR image to coregister this and the original SAR image, but calculates displacement based on orbit parameters and a DEM. The Range Doppler algorithm is much faster in processing scenes. When comparing scenes with both SARSIM and Range Doppler methods, I find no difference in the final product. However, the Range Doppler method does not work for quite a few of my scenes. If I understood ESA correctly, this is due to not accurate enough data in the SAR metadata, such that calculations of the displacement is incorrect. This appears to be special with data from the Arctic regions

I havent therefore used this one that much, but in other areas of the world it may be worth using the Range Doppler Terrain Correction.

Choose Geometry>Terrain Correction>Range Doppler Terrain Correction  (in Graph Builder choose "Terrain Correction"). The settings are as follows