[vtkusers] Re: Mapping/Interpolate scalars in a suitable way on a Finite Element Mesh

[Peter Wallin]

Im using the vtkBandedPolyDataContourFilter and it works fine, thanks for your help, I must have overlooked that filter somehow.

thanks for all your answers!

Regards,

Peter
----- Original Message -----
From: Steve Joyce <Steve.Joyce at sercoassurance.com>
Date: Thursday, October 14, 2004 4:50 pm
Subject: Re: Mapping/Interpolate scalars in a suitable way on a Finite	Element Mesh

> Hi,
> 
> The interpolation is by colour rather than by value by default.
> However, I've obtained reasonable results using a
> vtkBandedPolyDataContourFilter, which uses the value interpolation
> defined for the cell type to create sub-cells of a given scalar value,
> which are then coloured. The number of sub-cells depends on your node
> values and the number of values you have specified for the filter. It
> works like a normal contour filter, but fills in the contours with the
> appropriate colour (hence the name). Note that point scalars get
> converted to cell scalars by this filter. I've only tried this for
> linear hexahedrons so far.
> 
> Steve
> 
> >>> vtkusers-request at vtk.org 14/10/2004 15:26:16 >>>
> 
> ------------------------------
> 
> I have read in a mesh from a Finite Element solver, into VTK and 
> now I
> want to map the stresses( point scalars) in a suitable way. The values
> are mapped correctly in the points(nodes) but the interior of the cell
> looks bad.
> 
> I have attached two pictures that shows the mapping. As seen in the
> images, the diagonal of the quads has a constant value i.e. the result
> is interpreted as two planar triangles. In a case with a quad element
> and with a non-planar response surface this is not a good
> representation. 
> 
> 
> I want the mapping to be like a contour filter that clearly show the
> stresses around a certain point(s). Any suggestions? Is it 
> possibly to
> somehow use the contourfilter on my scalars?
> 
> 
> 
> 
> code extraction...
> 
> 
> this->lut=vtkLookupTable::New();
> this->lut->SetTableRange(this->filereader->GetOutput()-
> >GetScalarRange());this->lut->SetHueRange(0.667, 0.0);
> this->lut->Build();
> 
> 
> this->bar=vtkScalarBarActor::New();
> this->bar->SetLookupTable(lut);
> this->bar->SetNumberOfLabels(8);
> 
> 
> 
> this->pMapper=vtkPolyDataMapper::New();
> this->pMapper->SetInput(gFilter->GetOutput());
> this->pMapper->SetLookupTable(lut);
> this->pMapper->SetScalarRange(this->filereader->GetOutput()-
> >GetScalarRange());
> 
> // furhter down the pipeline..
> 
> 
> this->actor->SetMapper(dataMapper);
> //this->actor->GetProperty()->SetInterpolationToFlat();
> this->actor->GetProperty()->SetInterpolationToGouraud();
> this->actor->GetProperty()->SetAmbient(0.4);
> this->actor->GetProperty()->SetDiffuse(0.2);
> this->actor->GetProperty()->SetSpecular(0.2);
> .....
> 
> Best Regards,
> 
> Peter
> 
> 
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