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

[Simon Praetorius]

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>:
>>
>>     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
> Web:https://tu-dresden.de/Members/simon.praetorius
>
> _______________________________________________
> Dune-devel mailing list
> Dune-devel at lists.dune-project.org
> https://lists.dune-project.org/mailman/listinfo/dune-devel

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