how do we encode ghost cells such that VisIt can correctly extract them with "Inverse Ghost Zone"

[jfavre]

I am unable to properly encode ghost zones in Ascent such that VisIt (v3.3.3) reading back the Blueprint HDF5 file would recognize the cell-data as such and show them to me with an "Inverse Ghost Zone"

reading VTKFormat.html
it would seem like the special label "avtGhostZones" would be recognized
so I added the following to my Conduit description

`ascent_options["ghost_field_name"].append() = "avtGhostZones";

mesh["fields/avtGhostZones/association"].set("element");`

I can pseudo-color all other variables, except the "avtGhostZones" (no coloring appears). fine. But Inverse Ghost Zones does not show me any cells!

if instead I encode my Conduit node with a more generic name, such as "ghost", i.e.
`ascent_options["ghost_field_name"].append() = "ghost";

mesh["fields/ghost/association"].set("element");`

VisIt lets me make a pseudocoloring of it (see attached screenshot for a 4 MPI task job (this is a 2D problem), but I still cannot apply 'inverse ghost zone'

End of the day, I would expect that Ascent would take any name I specify as "ghost_field_name" and make a blueprint HDF5 file with corresponds to what VisIt expects. I'd appreciate some guidance. TIA

[cyrush]

@jfavre The VisIt blueprint plugin does not support ghost zone identification yet.

For ghost zones in Ascent (as you report) we do use a field to indicate ghost zones & Ascent allows you to specify this name and it will use that field as ghosts in its pipelines.

However it does not cull ghost zones before blueprint export.

Calling it avtGhostZones may actually confuse VisIt. There is some general logic in VisIt for debugging related to that name.

I recommend giving it your own name (ghost_zones) and to work around the limitation in VisIt -- manually apply a threshold operator to exclude the ghosts.

[jfavre]

Thanks @cyrush !