Dear everyone,
The images below are ERT resistivity pseudosections. Please look at the red circled part.
I realized some of the models have blurry or has very limited information (as the L06), while some of the models have so many data (L10).
I wonder if this is due to over removal of data points at the "externate bad data points" and also over filtering at the "RMS error statistic". However, only these two method can reduce the RMS error of the model.
Please help to answer if you know what does this representing. I really appreciate your help.
That top panel is your apparent resistivity value or your forward model. it is the bottom panel which is your inversion that matters. However, not knowing anything else about this survey, I would guess that this can possibly relate to operational human errors when installing the survey line. Your error is not extremely high but it is also not low. This is a high error for 8 iterations of DD array. I would guess something went wrong when installing the electrodes. the electrode contact might not have been good or some of the electrodes might not have been properly connected with the cable. Look at your inversion, is it showing something that you originally anticipated?
The profile picture on Facebook has a pixel limitation that you might not be aware of. If your picture exceeds the pixel restriction, the picture is automatically adjusted and the quality will be reduced. Right format: The right image format is important to avoid the blurry end result.
Several reasons could be attributed to such problem, and I can mention four of them here:
1- Exterminate bad data points reason: you maybe exterminated many data points from acquired profile.
2- RMS data filtering: maybe you removed many data points from the RMS window to minimize inversion error, and I normally don't prefer to do so, but try not to play in this module unless you know what you are doing.
3- System or acquisition problem: maybe the problem is due to uneven electrode spacing were experienced in the field, also maybe the topography was very irregular and was not taken into account.
finally, to summarize what I said, I'd Highley recommend you re-import your dataset in RES2DINV software and not play in the exterminate bad data points module or the RMS module and give it a try, also try to import topography of the surface "elevations of electrodes " (if any) and finally, in the future make sure to firmly place the electrodes in the ground to avoid many problems (I.e., high RMS error, or high contact resistivity) and take IP measurements along with ERT for the same profile as the both can be combined to make your interpretation reliable and help in error analysis.
and feel free to send me the dataset and all the information related to the survey (system utilized, Acquistion parameters, and profile's location). Wish this helps.
Muhammad A. El Hameedy
Hi
This looks like a graphics plotting issue as the measured res and calculated res images are reasonably similar (as they should) and the inversion would seem to be a reasonable inversion of what can be made out from the first two distorted images therefore the data seems fine and it is just its plotting in the first two images. Have you checked the example data sets to see if you get the same error?
Paul C
Either there is a missing data or the resistivity array methods are different. Another factor could be over iteration.
Might be useful to email me one of your data files and I'll run them through my RES2DInv and see what happens. [email protected]
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