[Paraview] ImageData extent overlapping within MPI Catalyst pipeline

[Utkarsh Ayachit]

Luigi,

For an image data distributed across multiple ranks with no ghost
cell, there still exists a single point overlap for the points. The
points along the shared boundary are expected to be duplicated among
ranks.  I am thinking your 3D regular grid should be mapped as
cell-data rather than point data. Thus when creating the image, try
setting the point extents as 1+cell-extents and then pass your data to
the cell data arrays rather than point data.

e.g.

int cell_exts[6] = { local domain exts };
int point_exts[6] = { cell_exts[0] , cell_exts[1] + 1,
                                cell_exts[2], cel_exts[3] + 1,
                                cell_exts[4], cel_exts[5] + 1};
vtkNew<vtkImageData> data;
data->SetExtent(point_exts);
data->GetCellData()->SetScalars(...<vtkDataArray subclass with 3d grid data> );

Utkarsh

On Fri, Aug 19, 2016 at 1:42 PM, Luigi Calori <l.calori at cineca.it> wrote:
> We are newbie in Catalyst, trying to instrument two CFD MPI simulation codes
> that both have 3d  regular grid
>  as it' s data structure. We have followed the fortran example and used
> ImageData for both codes.
> The two code are different in the distribution of the memory among
> processors:
> one is a differential one who keep overlapping extents among processors:
> this gave no problems.
> The other does not have any overlapping as it using 2d fft decomposition.
> The imagedata extents of each processor do not overlap as there is no need
> of "ghost" cells.
> This result in a strange bug in filter slicing:
> If the slicing is done in the paraview client ( the whole field is passed to
> client) and we slice there, slice is ok.
> If the slicing is done in the catalyst pipeline, the slice has gaps.
>
> As one difference is the overlapping of each processor extent, is it
> REQUIRED that there is some overlapping of
> PointData extents?
>
> Thanks in advance for any help
>
> Best
>
> Luigi
>
> --
> Luigi Calori
> SuperComputing Applications and Innovation Department
> CINECA - via Magnanelli, 6/3, 40033 Casalecchio di Reno (Bologna) - ITALY
> Tel: +39 051 6171509  Fax: +39 051 6132198
> hpc.cineca.it
>
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