ERT: blanked out cells when adding new regions to the mesh

[amehriban]

Hello dear pygimli team,

I am working with an ERT dataset where electrodes are placed both under the water (on the seabed), and on land (on an island). We have some CTD measurements taken on the same day as ERT was done, so we have some idea of the water layer resistivity. I therefore added to the mesh two regions that represent water (north and south of the island) and set regularization limits based on the range of water resistivity from CTD. This is the result that I get:

(https://github.com/gimli-org/gimli/assets/119584593/fa25b473-4c1c-4fe3-b19b-41926b24c7b6)

My question is: what could be the possible reason of the blanking out of some cells here and there? Does it somehow indicate a problem with the mesh?
When I run the inversion without adding the water regions, it looks normal:

(https://github.com/gimli-org/gimli/assets/119584593/8f11335b-aa35-4db8-88f6-33440923cab0)

"question"

[halbmy]

Thank you for reporting this.

Obviously, the coverage vector is not correctly mapped back according to the region markers. In case of regions, the model cells are renumbered by increasing region number. Whereas this is accounted for the model vector, there is obviously a bug for the coverage that needs to be corrected. In the meanwhile you can avoid alpha shading by showResult(..., coverage=1).

[amehriban]

Thank you very much!

[halbmy]

This was indeed a bug that I corrected by e7b51cc so that the region example works as expected:
https://dev.pygimli.org/_tutorials_auto/3_inversion/plot_8-regionWise.html#region-specific-regularization

[amehriban]

Thank you very much for such swift response and solution! can confirm, it works now