[vtkusers] Create a color map using polyData in VTK

[David Doria]

On Fri, Feb 3, 2012 at 2:19 AM, Gishara Indeewarie <gish.777 at gmail.com>wrote:

> Hi all,
>
> I have a set of points (x,y,z) and the values of each point. I have
> created a surface according to the following example.
>
> http://www.vtk.org/Wiki/VTK/Examples/Cxx/Filters/SurfaceFromUnorganizedPoints
>
>
> And I want to create a color map by giving colors to each point according
> to the value of each point.
> My problem is that I can't see the color map in my example. All I see is
> the surface with a plain color.
> The code is as below:
>
> vtkPoints *points = newPts;//ReadCFDData2();
> vtkSmartPointer<vtkPolyData> polydata
> = vtkSmartPointer<vtkPolyData>::New();
>   polydata->SetPoints(points);
>
>   vtkSmartPointer<vtkDoubleArray> weights =
> vtkSmartPointer<vtkDoubleArray>::New();
>   weights->SetNumberOfValues(PoValues.GetSize());
>   for(int i=0; i< PoValues.GetSize();i++){
>   weights->SetValue(i, PoValues[i]);
>   }
>   polydata->GetPointData()->SetScalars(weights);
>
>   vtkSmartPointer<vtkVertexGlyphFilter> glyphFilter =
>     vtkSmartPointer<vtkVertexGlyphFilter>::New();
> #if VTK_MAJOR_VERSION <= 5
>   glyphFilter->SetInputConnection(polydata->GetProducerPort());
> #else
>   glyphFilter->SetInputData(polydata);
> #endif
>   glyphFilter->Update();
>
>   // Create a plane to cut
>   vtkSmartPointer<vtkPlane> plane =
>     vtkSmartPointer<vtkPlane>::New();
>   plane->SetOrigin(polydata->GetCenter());
>   plane->SetNormal(1,1,1);
>
>
>   // Construct the surface and create isosurface.
>   vtkSmartPointer<vtkSurfaceReconstructionFilter> surf =
>     vtkSmartPointer<vtkSurfaceReconstructionFilter>::New();
>
>   surf->SetInput(polydata);
>  //
>   vtkSmartPointer<vtkContourFilter> cf =
>  vtkSmartPointer<vtkContourFilter>::New();
>   cf->SetInputConnection(surf->GetOutputPort());
>
>    // Create the color map
>   vtkSmartPointer<vtkLookupTable> colorLookupTable =
> vtkSmartPointer<vtkLookupTable>::New();
>   colorLookupTable->SetNumberOfColors(64);
>   colorLookupTable->SetHueRange( 0.0,0.667);
>   colorLookupTable->SetTableRange(0,3);
>   colorLookupTable->Build();
>
>   // Create a mapper and actor
>   vtkSmartPointer<vtkPolyDataMapper> mapper =
> vtkSmartPointer<vtkPolyDataMapper>::New();
>
> mapper->SetInputConnection(/*reverse->GetOutputPort()*/cf->GetOutputPort());
>   mapper->ScalarVisibilityOff();
>   mapper->SetLookupTable(colorLookupTable);
>
>   vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
>    actor->GetProperty()->SetColor(1.0, 0.8941, 0.7686); // bisque
>   actor->SetMapper(mapper);
>
>   //Create a renderer, render window, and interactor
>   vtkSmartPointer<vtkRenderer> renderer
> = vtkSmartPointer<vtkRenderer>::New();
>   vtkSmartPointer<vtkRenderWindow> renderWindow
> = vtkSmartPointer<vtkRenderWindow>::New();
>   renderWindow->AddRenderer(renderer);
>   vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor
> = vtkSmartPointer<vtkRenderWindowInteractor>::New();
>   renderWindowInteractor->SetRenderWindow(renderWindow);
>
>   //Add the actor to the scene
>   renderer->AddActor(actor);
>   renderer->SetBackground(.3, .6, .3); // Background color green
>
>   //Render and interact
>   renderWindow->Render();
>   renderWindowInteractor->Start();
>
> Please explain me where I have gone wrong. Thanks a lot.
>
> --
> Gish
>

Why are you setting a color on the actor if you want the lookup table to
provide the colors?
   actor->GetProperty()->SetColor(1.0, 0.8941, 0.7686); // bisque ?

Here is a working example of using a color map:

http://www.vtk.org/Wiki/VTK/Examples/Cxx/Meshes/Color_a_mesh_by_height

See if that helps.

David
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