Existing visualization tools? DG support?

[ibaned]

Hello, this project looks interesting!
I have a couple of questions:

1. What visualization tools read this format or are actively being enhanced to read this format?
2. Is there or will there be support for Discontinuous Galerkin fields?

Thanks!

[v-dobrev]

Discontinuous fields are definitely supported:

FMS/src/fms.h

Lines 316 to 322 in bdccccb

	typedef enum {
	FMS_CONTINUOUS, // H1-conforming
	FMS_DISCONTINUOUS, // "L2-conforming"
	FMS_DISCONTINUOUS_WEIGHTED, // "L2-conforming" volume weighted
	FMS_HCURL, // H(curl)-conforming
	FMS_HDIV // H(div)-conforming
	} FmsFieldType;

Regarding visualization: FMS is still in the early prototype stage, so there is no support for it in any visualization tool. However, one of the main goals of FMS is to promote (and serve as the basis for) broader adoption and support for high-order meshes and fields in visualization tools.

We (the CEED ECP project) will be talking to the ECP visualization projects (which include members of the ParaView and VisIt teams) to get their feedback and discuss a path forward for adding support for FMS in VisIt and ParaView.

Currently, FMS defines only a data exchange interface and the idea is to implement file I/O format(s) on top of this interface.

For postprocessing and visualization, one will probably need a finite element library to interpret the basis function and degree-of-freedom specifications used by FMS and provide a richer mesh and field query interface.

[tzanio]

To add to @v-dobrev's answer: as shown in the PUMI/MFEM example, we can read the FMS data in MFEM, convert to MFEM's mesh and visualize with GLVis, so that's one option that could be used currently.

[ibaned]

@tzanio so for PUMI/MFEM is FMS the middleman, e.g. PUMI -> FMS -> MFEM?
I'll look into GLVis, thanks!

[tzanio]

@ibaned: yes, see https://github.com/CEED/FMS/blob/master/examples/README.md

[bangerth]

Interesting. We'd be interested to write the corresponding interfaces in deal.II as well.

VTK in newer versions has support for higher order polynomial fields defined on individual cells. This seems to work reasonably well in Paraview already, and we can write these from deal.II. Since essentially every finite element is a subset of a (complete) polynomial space of sufficiently high degree, this allows exact visualization. deal.II implemented this in dealii/dealii#6994 and some follow-up patches.

[v-dobrev]

Hi @bangerth,

We're glad you are interested!

We are trying to engage as many FE libraries/applications as possible, so we can create a rich, arbitrary order FE-focused mesh and data exchange interface and file format (or suite of file formats).

The FMS data exchange interface is a first beta (v0.1), so any feedback on that is welcome.

Thanks,
Veselin