[Paraview] Disappearing volume rendering?

[B.W.H. van Beest]

Yes, I do set a scalar for each cell. I left them out in the example, as
also with a scalar I couldn't get a volume display.

I'm not sure what you mean by "adjusting the transfer function".

Regards,
Bertwim



On 10/13/2014 07:28 PM, Burlen Loring wrote:
> do you have any scalars? those are not optional for volume rendering.
> Additionally you may need to adjust the transfer function,
>
> On 10/13/2014 10:22 AM, B.W.H. van Beest wrote:
>> No, it doesn't work. The filter creates tets, which are visible in the
>> wireframe representation,
>> but when I select "Volume"  representation the image disappears.
>>
>> I can't imagine it is so difficult to render a volume in Paraview. I
>> must be doing something wrong....
>>
>> Regards,
>> Bertwim
>>
>> On 10/13/2014 05:36 PM, Cory Quammen wrote:
>>> Bertwim,
>>>
>>> I'm not sure that the volume renderer can handle VTK_HEXAHEDRON
>>> elements. Try the "Tetrahedralize" filter on your source and see if
>>> the Volume representation works.
>>>
>>> Thanks,
>>> Cory
>>>
>>> On Mon, Oct 13, 2014 at 10:19 AM, B.W.H. van Beest <bwvb at xs4all.nl>
>>> wrote:
>>>> Hi,
>>>>
>>>> I'm struggling to get a proper 3D view of my model system (yes,
>>>> embarrassing!)
>>>> but must admit my defeat.
>>>> After stripping almost everything, keeping the minimum to exhibit the
>>>> issue,
>>>> I'm left with the following:
>>>>
>>>> I have created a simple box source. To get a 3D representation, I
>>>> sub-classed
>>>> the code for this Source from vtkUnstructuredGridAlgorithm.
>>>>
>>>> In the RequestData method, I define the 8 point of the unit cube. I
>>>> added the points to the
>>>> underlying unstructed grid, and I specified the cell topology.
>>>>
>>>> This all seems to work: when instantiating this box Source, I *do*
>>>> get the
>>>> expected cube in the representations (Surface, wireframe, Points).
>>>>
>>>> However, when I select the "Volume" representation, *the image
>>>> disappears*
>>>> What am I doing wrong?
>>>>
>>>> As the code is not too long and very simple, I take the freedom to
>>>> paste
>>>> it below.
>>>>
>>>> Kind regards.
>>>> Bertwim
>>>>
>>>> =========================================
>>>>
>>>>   int sphBoxSourceC::RequestData( vtkInformation *vtkNotUsed(request),
>>>>                                  vtkInformationVector
>>>> **vtkNotUsed(inputVector),
>>>>                                  vtkInformationVector *outputVector)
>>>> {
>>>>     // Get the info object
>>>>     vtkInformation *outInfo = outputVector->GetInformationObject(0);
>>>>     vtkUnstructuredGrid *umesh = vtkUnstructuredGrid::SafeDownCast(
>>>> outInfo->Get( vtkDataObject::DATA_OBJECT() ) );
>>>>
>>>>     // Pre-allocate some memory
>>>>     umesh->Allocate( 1024 );
>>>>
>>>>     // Specify points.
>>>>     double r0[] = { 0.0, 0.0, 0.0 };
>>>>     double r1[] = { 1.0, 0.0, 0.0 };
>>>>     double r2[] = { 0.0, 1.0, 0.0 };
>>>>     double r3[] = { 1.0, 1.0, 0.0 };
>>>>     double r4[] = { 0.0, 0.0, 1.0 };
>>>>     double r5[] = { 1.0, 0.0, 1.0 };
>>>>     double r6[] = { 0.0, 1.0, 1.0 };
>>>>     double r7[] = { 1.0, 1.0, 1.0 };
>>>>
>>>>     // Collect the points in a vtk data structures.
>>>>     {
>>>>        vtkSmartPointer<vtkPoints> points =
>>>> vtkSmartPointer<vtkPoints>::New();
>>>>        points->SetDataType( VTK_DOUBLE );
>>>>
>>>>        points->InsertNextPoint( r0 );
>>>>        points->InsertNextPoint( r1 );
>>>>        points->InsertNextPoint( r2 );
>>>>        points->InsertNextPoint( r3 );
>>>>        points->InsertNextPoint( r4 );
>>>>        points->InsertNextPoint( r5 );
>>>>        points->InsertNextPoint( r6 );
>>>>        points->InsertNextPoint( r7 );
>>>>
>>>>        // Transfer points to umesh.
>>>>        umesh->SetPoints( points );
>>>>     }
>>>>
>>>>     // Cell Topology
>>>>     vtkIdType vtx[8] = { 0, 1, 3, 2, 4, 5, 7, 6 };
>>>>     umesh->InsertNextCell( VTK_HEXAHEDRON, 8, vtx );
>>>>
>>>>     return 1;
>>>> }
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Powered by www.kitware.com
>>>>
>>>> Visit other Kitware open-source projects at
>>>> http://www.kitware.com/opensource/opensource.html
>>>>
>>>> Please keep messages on-topic and check the ParaView Wiki at:
>>>> http://paraview.org/Wiki/ParaView
>>>>
>>>> Follow this link to subscribe/unsubscribe:
>>>> http://public.kitware.com/mailman/listinfo/paraview
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the ParaView Wiki at:
>> http://paraview.org/Wiki/ParaView
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/paraview
>
>
>