HI! I have 2 sentinel 1 SLC image, with baseline 172m. I do Insar interferometry process with snaphu, so export and previus to "unwrapper " option, I read the config file, and now the baseline is setted to other baseline. Is an error? I can´t understand what is going on there…
the perpendicular baseline is estimated for SLC products and can change after application of the orbit file. This is what we observe in the Stack Overview 170.92 (before) and 172.18 (after).
The difference between SNAP (172) and snaphu (215) is interesting and I do not have an explanation, so far. But I would be interested if this has an impact on the unwrapping result. So if you want to copy the snaphu folder, change the BASELINE value to 172 and run it again, we could compare if the results.
Maybe someone knows why the value used by snaphu is different.
thank you - that is interesting. So the larger baseline (215, left) produces higher terrain variation) than the smaller one (172, right). Which one is closer to the SRTM data? You could calculate a difference image to test.
I have no idea why the values are different in SNAP and snaphu, but we should clarfiy it, as it makes a real difference.
@lveci@jun_lu Do you have an explanation why the baseline in the snaphu metadata differs from the one from SNAP?
@hriston_bg How do you call them ? I mean, i understand they are different things(thanks for that), but i want to be sure going from baseline to perpendicular baseline, or vice versa. Thanks again
The figure shows a sketch of the acquisition geometry for repeat pass interferometric acquisition. The vector between the two orbital positions at times 𝑡0 and 𝑡1, respectively, is called the baseline. The components of the baseline along (Δ𝑅) and across (𝐵⊥) the direction from satellite to target influence the range difference Δ𝑅 between the two acquisitions, and hence the interferometric phase.