[Dune-devel] VTK writer for intersection or codim=1 entity data?

[Ospina De Los Rios, Santiago]

Dear Simon and Christian ,


many thanks for the input, @Christian, yes, access would be very much appreciated! I will check later this week how these work on my application.


Best,

Santiago

________________________________
From: Dune-devel <dune-devel-bounces at lists.dune-project.org> on behalf of Simon Praetorius <simon.praetorius at tu-dresden.de>
Sent: Friday, June 23, 2023 5:02:10 PM
To: dune-devel at lists.dune-project.org
Subject: Re: [Dune-devel] VTK writer for intersection or codim=1 entity data?


See

https://gitlab.dune-project.org/extensions/dune-vtk/-/merge_requests/47

for an example implementation of an edge-datacollector, or more generally a data-collector that collects data from any requested codim sub-entity-set.

Best,
Simon

On 6/22/23 15:41, Simon Praetorius wrote:

Hi Santiago,

Maybe this is also similar in dune-vtk. There, the "extractor" is called "datacollector". You can implement an interface where you can essentially collect whatever you want. But there is no example for intersection grids.

In the simplest form you could follow the ContinuousDataCollector. If you do not have a parallel grid it can even be simplified. The numPoints() function should return the number of vertices in the grid and the numCells() function the number of edges. The points() implementation is the same as in the continuous data-collector and the cells() function just iterates over the edges instead of the elements. The only thing where you need to be a bit careful is the pointData() (or cellData()) function. The input is a grid-function. The abstraction is currently not general enough to allow grid-functions to be bound to entity sets that are not the elements of the grid. Thus, the implementation for the pointData() should be the same as a the ContinuousDataCollector and for the cellData() you just need to evaluate in e.g. the edge centers instead of the element centers.

I hope you got an idea of how to implement it. As I said, it is not yet tested and I cannot give any guarantees that it works. But if it does, it would be great if you could contribute this to the repository.

Best,
Simon

On 6/22/23 08:05, Christian Engwer wrote:
Dear Santiago,

long ago I implemented something like that to visualise data of a UDG discretization. I'm partially using the dune-grid vtk writer, but defined a different "extractor" to collect the data.

We never polished it, if you want, I can give you access.

Best Christian


Am 22. Juni 2023 06:40:14 MESZ schrieb "Ospina De Los Rios, Santiago" <santiago.ospina at iwr.uni-heidelberg.de><mailto:santiago.ospina at iwr.uni-heidelberg.de>:
Dear Dune Developers,

I was wondering if any of you had faced the problem of writing data for intersection data for VTK? In particular, I am interested in 0D/1D/2D VTK meshes+data (not C++ grids) resulting from the intersection between the 1D/2D/3D non-overlapping domains of a grid. So far, I only use conforming grids, so either interesection or codim:=1 entity writers would do for me.

I could not see any hint to these kind of writers in the dune-grid and dune-vtk modules. Maybe I missed it? So I was wondering if any of you already had similar problem/solution or if you see an easy way to re-use the existing writers for this purpose? Any pointer would be appreciated, thanks!

Best,
Santiago



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Dr. Simon Praetorius
Institut für Wissenschaftliches Rechnen
Fakultät Mathematik
Technische Universität Dresden
Tel.: TUD-34432
Mail: simon.praetorius at tu-dresden.de<mailto:simon.praetorius at tu-dresden.de>
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--
Dr. Simon Praetorius
Institut für Wissenschaftliches Rechnen
Fakultät Mathematik
Technische Universität Dresden
Tel.: TUD-34432
Mail: simon.praetorius at tu-dresden.de<mailto:simon.praetorius at tu-dresden.de>
Web: https://tu-dresden.de/Members/simon.praetorius
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