Is an ellipsoid correction necessary after the slant-to-ground-range to project to WGS84

s1tbx
#1

Hi,

Suppose that I’m working with Single Look Complex images from Sentinel-1 (or any other SAR sensor).
Right now, I’m carrying out only the Slant range to ground range projection on these images, and the resulting image’s geometry seems a bit different (distorted) from the optical one I’m visualizing on Google Maps.

Is it necessary to perform an Ellipsoid correction after the slant range to ground projection to have the image projected into the WGS84projection, and therefore to obtain a geometry that is similar to the one shown on Google Maps?

Thanks.

#2

Yes, use the average height EC if your data is flat or in the ocean. Otherwise, you should use range Doppler terrain correction.

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#3

When I flip the SAR image horizontally prior to the Slant-range-to-ground-range + Terrain Correction processing, the coregistration I’m doing afterwards is worse than when I omit the `Flip operator.

Is there an explanation for this error in the coregistration?

#4

You do not need to flip nor do slant-to-ground. Just use the terrain correction directly.

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