Hi,
I am playing with S1Tiling to generate gamma-rtc calibrated images. I noticed some kind of “lines” artifacts in the output images, particularly in mountain area. These artifacts seem to come the gamma area map itself.
Below is a screen capture (area is located on MGRS tile 31TDH, orbit #132). Most values are roughly in the [25, 500] range, and white pixels where the lines are, carry very high values (say > 1000).
I used a 30m resolution SRTM DEM, with there settings:
[Processing]
cache_dem_by: copy
calibration: gamma_naught_rtc
remove_thermal_noise: True
lower_signal_value : 1e-7
use_resampled_dem: True
resample_dem_factor_x: 2.0
resample_dem_factor_y: 2.0
distribute_area: False
min_gamma_area: 1.0
calibration_factor: 1.0
output_nodata: False
output_spatial_resolution : 10.
orthorectification_gridspacing : 40
orthorectification_interpolation_method : bco
mode : Normal
# Required for gamma maps
ram_per_process : 70000
disable_streaming.gamma_area : True
creation_options.s1_on_dem : float64 COMPRESS=DEFLATE, BIGTIFF=YES, PREDICTOR=3, TILED=YES, BLOCKXSIZE=1024, BLOCKYSIZE=1024
In Small et al. it is stated that a low res DHM (less than the image resolution) would cause some content loss. Do you think that the `resample_dem_factor_x/y` is the culprit here? Should/could I configure my process differently to avoid these obviously not expected artifacts?
Many thanks for this magnificent piece of software, and for your help!