[itishappy]

If my understanding is correct (and I'd love to be corrected if not!), it can be used to generate super accurate differential heightmaps. It won't tell you exactly how high a peak is, for example, but it can tell you that it's dropped a few millimeters since the last time you measured.

https://en.wikipedia.org/wiki/Interferometric_synthetic-aper...

[lmc]

Typically you will get an image pair for an area every 6-12 days. The phase used in interferometry is massively affected by atmospheric conditions, which can vary a lot in this time, and are difficult to correct for. So, one pair is often not enough for this. But if you look at a bunch of pairs for that area over a longer time period, you might be able to correct for the atmospheric effects and get your differential height map. You can get more accurate elevation models 'out of the box' with different systems, e.g., the SRTM (one of the most well known publicly available global elevation maps) [1] was made with insar but 2 antennas on one craft, and Germany's TanDEM-X [2] is a pair of satellites flying in formation a few hundred meters apart, capturing the same area at the same time.

[1]: https://www.earthdata.nasa.gov/data/instruments/srtm [2]: https://en.wikipedia.org/wiki/TanDEM-X