A forum to discuss the optical processing services for ground deformation


#1

Hi all!
We just setup a forum to report experiences on the use of the optical services (MPIC, DSM-OPT, ALADIM) dedicated to ground deformation analysis (earthquakes, landslides).
Do not hesitate to report any successful or unsuccessful runs of the services, or any new functions that you would like to be implemented.

Jean-Philippe for the CNRS-EOST team


#2

Hello to everyone,
I will summarize in few comments my experience using the ground deformation analysis tools from GEP.

  1. ALADIM was added recently in my toolbox, but I havent found any description about the workflow (parameters, upload file formats etc) even outside GEP.

  2. DSM-OPT tool; run a few test runs using the available sample datasets (Pleiades). However, a description of custom upload files is needed - native product zip format or separate files?

  3. MPIC-OPT; As I used this tool a lot more than the other ones, I will offer more extensive comments and feedback about this. The two papers from Stupf et al. 2017/2018 offered some helpful insight into the processing chain, including my own experience in using MicMac for displacement analysis.
    MPIC-OPT generally seems to work, with some exceptions that I will describe below, mapping ground displacement at a Sentinel-2 tile scale. Havent really tried time-series examples for landslide displacement, as my main focus was on co-seismic large horizontal displacements.

Positive/encouraging aspects:

  • Large area covered - full Sentinel-2 tile
  • Parameters on tool panel are kept quite simple and fast to use once familiar with the tool
  • Export includes multitude of file products, which is useful
  • Inverse matching is important, as in many cases there is observable difference in outcome

Disadvantages/problems:

  • There is an issue with Sentinel-2 single-tile compatibility. Some specific tiles (usually older than 2017 but some recent too) are incompatible and the tool fails. This must be related to some format issues at the GEP repository.
  • There should be an option to a) manually input some parameters and b) deactivate cloud masking. Most of the examples I ran, had the issue of cloud masking overkill: cloudless tiles over desert/arid areas had large parts missing due to erroneous masking, while in other scenes cloud masking removed urban-semi-urban areas that had no clouds or haze.
  • From the relevant publications, I’ve understood that MPIC-OPT uses the coregis process or a variant for scene pre-processing and correction (destriping/deramping). However, most runs had some visible artifacts, especially stripes. Deramping mostly worked on most cases - I run separately the same images using MicMac and usually there was a significant ramp present that needed correction, which wasnt present on MPIC-OPT products (although this could be an effect of better co-registration).
    Some examples from Sentinel-2 tile and pushbroom artifacts in MPIC-OPT products:

MPICOPT_Stripe
Px2 RGB

MPICOPT_Stripe2
Px2 RGB

  • As the Px1 / Px2 are the basic output products, there should be an option to convert in map units, or a description of how to do the conversion manually. Although I am familiar with this, few people do know in depth the MicMac/MM2DPosSism processing and they would find this trivial.

Hope to have offered some insight into the sucess and issues encountered using the optical ground deformation tools. I will post any new progress/issues as they come around.

Sotiris Valkaniotis