Interferogram or Coherence tool in snappy?

I am following a paper and am trying to write their process with snappy. It is talking about using coherence and they posted the method (picture below) they used with snap and I am wondering why one should create a product using the Interferogram tool instead of the Coherence tool? I am a little confused about what the difference is. Doesn’t an interferogram create a coherence raster?

Coherence Estimate coherence from stack of coregistered images
Interferogram Compute interferograms from stack of coregistered S-1 images

Thanks as always!

You need the interferogram tool because that is the tool that calculates the actual phase map used to calculate elevation change. Coherence shows the reliability of the pixels. You cannot do InSAR using coherence only.

The Interferogram tool generates both inteferogram and coherence rasters.

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As InSAR processing is computationally demanding you should do your processing via GPT to avoid large performance degradation due to snappy/Python. You can use the snapista Python wrapper:

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