I Want to monitor the surface subsidence of my specific study area from year 1990 to 2015 with “SAR Interferometry”
so my question is that is any satellite which provide data in this range of Time…??
or can I use 2 different satellite data for SAR Interferometry…??
Like RadarSAT 1 and RadarSAT 2
I am currently working on surface subsidence using a stack of SENTINEL-1 images. I understand that the more images we stack, the more the atmospheric error is minimized.
So, my question is:
Lets say i have five images, perform the interferometric processing (pair1-pair2, pair2-pair3, pair3-pair4,pair4-pair5) and create a stack out of them. pair1-pair2 form the subsidence map1, pair2-pair3 form the subsidence map2, pair3-pair4 form the subsidence map3 and pair4-pair5 form the subsidence map4. Finally, i add them all up ( subsidence map1 + subsidence map2 + subsidence map3 + subsidence map4) to find the final displacement map. At the very end, i want to discard pixels values that have coherence value below 0.5.
So, do we just choose a random coherence layer out of the 5 pairs to masks out the low coherence values?.
Do we add up the coherence layers as we did for the subsidence map?
Do we multiply each coherence layer and the we mask it out?
Calculate an average coherence with the band maths and apply one threshold (0.5 seems too high for a mean value because the raster values will generally be lower after the averaging and not many areas will remain. Maybe 0.3)
Apply a threshold of 0.3 for every coherence image to get 5 binary masks. You then multiply all masks and have values of 1 remaining at pixels which were above 0.3 at all times and 0 where coherence fell below the threshold at least once.
multi-looking can improve the image/interferogram quality, but inevitably reduces the resolution. So if you don’t depend on the resolution of 10 meters of S1 you can perform it, but it is not required at all.
talking of the multi looking, i remarked that the resultant displacement obtained with a multi looked interferogram is different from that without multi looking the interferogram. is it due to the reduction of the resolution as said by @ABraun or something else. also which is more reliable, with or without the multi looking?
my second question is how do i add a stable point in my displacement map. following the tutorial from ESA, when i take the pixel value and add to the displacement map, it affects the lower but also the upper bound of the displacement histogram. i looks strange to me, is there a proper way to do it?
I’m using around 10 images for Subsidence studies,I updated orbital file and TopSAR-split, please tell me how to run batchprocessing for these ten images(1-2image, 2-3 image , 3-4 image and so on).
And then how to add these output to a single image ?
please clarify this doubt…
Thank you so much ABraun.
Please tell me how can i add these (1-2, 1-3, 1-4 ) SAR interferometric images to a single image (single output).
Means how can i add these images (1-2, 1-3 and 1-4) to a single image.
I stacked all the 12 displacement images(1master+11slave). and then Using Band Math i created one displacement_combine ((1+2+3+…12) / 12). then
how can i create profile plot from 2017-2020 displacement ?
and please tell + and - values indication in google earth map (means which part is uplifting or subsiding) ?