I’am using 12,5 meter resolution ALOS PALSAR DEM to geocode my SAR displacement Image. What is the ideal pixel spacing number for resampling if i use this DEM ? the default value that been given from SNAP is 15 meter which is bigger than the original ALOS DEM resolution.
the DEM is resampled to the input data, so you shouldn’t change this parameter by your own.
But it is very likely that you won’t benefit from the external DEM here, because the 12.5m DEM provided with ALOS RTC products originates from SRTM. So the 30m SRTM was upsampled to 12.5 (for ALOS RTC generation) and then is again downsampled to 15m in SNAP and you potentially lose information here.
Please see Table 1 in this document: https://asf.alaska.edu/wp-content/uploads/2019/03/rtc_product_guide_v1.2.pdf
Outside Hawaii and Alaska, the DEM is SRTM.
Simply selecting the SRTM 1Sec AutoDownload option will give you same (or even more precise) results.
Thanks a lot Mr. Braun.
I have another question, but kinda out of topic from this theme. Can we use DEM from UAV (ex : Drone DJI) which has sub-centimeter spatial resolution to process topographic phase removal to obtain higher interferogram accuracy? My problem to process it with ALOS/SRTM DEM is the current morphological in my location study is not representative at present time because of the eruption damage…
You can use it when it is projected to WGS84 and stored as GeoTiff, but maybe it makes sense to resample it to 1m or even more so SNAP can handle the size