Hello! I am trying to calculate canopy height from TanDEM-X and TerraSAR-X data using PolInSAR and RVoG-Model in PolSARpro, but I cannot import my data sets. The data is quadpol monostatic single baseline but when I select Dual Data sets in the environment it cannot find any files. I tried converting the files to bin.hdr in SNAP but it did not help. My best guess is that I need to generate S-Matrix files such as S11, S12, S21 and S22, since that is the output of the PolSARproSIM with which it works. I don’t know how to create these files and the articles I have read only state that they have generated the S-Matrix but they do not state how. I know that one can derive the Coherency (T) and Covariance (C) Matrix from the Sinclair-Matrix in SNAP but when I tried importing the T and C Matrix generated files instead that did not work either. I might be going about this all wrong, I am new to this field and I would greatly appreciate any help
Here is how I solved the PolInSAR Workflow for Tandem-X and TerraSAR-X data, I got the RVoG heights but note that there might be mistakes in my workflow and calculations so caution is advised. I just wanted to post it since I did not manage at all to get it to work before and it might be a good start for some wanting to test PolInSAR on their own data sets. Feel free to comment if you notice mistakes!
Import:
Environment > Single data set, set the path as close as possible to the folder with the Tandem-X/TerraSAR-X files. Click yes in warning message.
Import > Spaceborne Sensors > Tandem-X , go to common TDX/TSX file (.xml) and read header (rest should fill in automatically). Extract data, check yes when asked if you want to create new folders (master; slave).
Environment > Dual data sets > master set to the automatically created master folder and slave to automatically created slave folder.
Workflow PolInSAR:
Follow this workflow (second practical): Lecture Full Title
Tips:
Flat Earth:
The flat earth file can be generated in SNAP (create interferogram, check output flat earth phase, export band subset flat earth as PolSARPro .bin format)
Kz File:
The kz file can be generated by calculating kz and then using band math in SNAP, create new band with that value and export in PolSARpro format.
Kz (vertical wavenumber) calculation:
kz = 2pi x BT / Lambda x R x sin(0)
Source:
Noelia Romero-Puig , Student Member, IEEE, Juan M. Lopez-Sanchez , Senior Member, IEEE,
and J. David Ballester-Berman. (2020). “Estimation of RVoG Scene Parameters by Means of
PolInSAR With TanDEM-X Data: Effect of
the Double-Bounce Contribution” - Page 2, figure 5
Kz = vertical wave number
BT = perpendicular baseline
Lambda = Wavelength
R = Slant Range
0 = Incidence angle
Incidence angle (0):
Can be found in the metadata. I took the average of incidence near and incidence far. Needs to be converted to radians ( incidence angle x pi/180)
Effective baseline (B):
Found in the metadata (can open in SNAP).
Perpendicular baseline:
BT = B x cos(0)
Wavelength:
= c/f (speed of light / frequency). Frequency of X-Band can be found in metadata (unit: GHz)
Slant Range:
Found in metadata
Workflow for georeferencing and orthorectifying PolSARpro results for use in ArcGIS Pro:
- Import original satellite image into SNAP.
- Export metadata from original satellite image as subset into a folder (SNAP).
- Copy the .bin files (Result from PolSARpro) into the folder containing the exported metadata.
- Import the result file from PolSARpro into SNAP in PolSARpro format. Now SNAP should show the .bin file in the correct position in World View.
- For use in ArcGIS pro, apply terrain correction (do not check complex output box)
- Load the automatically generated .img file of the terrain corrected image into ArcGIS Pro.