[vtkusers] Render scene without shading, light, interpolation

[Ken Martin]

Did you make sure none of the points were shared between cells? That would
cause issues.

Other than that you want

renWin->SetMultisamples(0);  // MSAA will create interpolated pixels
actor->GetProperty()->SetAmbient(1.0)
actor->GetProperty()->SetDiffuse(0.0)
actor->GetProperty()->SetSpecular(0.0)

and you should be good. Interpolation **should** be irrelevant if the
cell's points have the same color.



On Wed, Nov 30, 2016 at 2:20 AM, Jaehyun Jang <sysexits at gmail.com> wrote:

> Dear vtk users,
>
> I am trying to these tasks using *vtkPolyDataMapper with
> vtkUnsignedCharArray*, *vtkRenderer, vtkRenderWindow *to get pixel count
> of a specific cell
>
> 1. Translate index value(within 1 ~ 16777215) to R, G, B value (using R =
> idx & 255, G = (idx >> 8) & 255, B = (idx >> 16) & 255
> 2. From all points of each cell, assigning those color values into *vtkUnsignedCharArray
> *with SetTupleValue(point index of same cell, color) (the forth value of
> color is always 255)
> - i.e, All different cells have different RGB value. (If I set only 50
> cells in the model, only 50 cells have distinct color in 1 ~ 50)
> 3. Setting the model using *vtkProperty *with these settings
>     m_actor->GetProperty()->BackfaceCullingOn();
>     m_actor->GetProperty()->LightingOff();
>     m_actor->GetProperty()->ShadingOff();
>     m_actor->GetProperty()->SetInterpolationToFlat();
>
> 4. Render this model using *vtkRenderWindow *with these settings
>     renderwindow->SetOffScreenRendering(1);
>     renderwindow->AddRenderer(renderer);
>     renderwindow->SetSize(600, 600);
>     renderwindow->Render()
> 5. Get vtkImageData using *vtkWindowToImageFilter *and access
> GetScalarPointer
> 6. Translate RGB to index and count it.
>
> However, RGB values translate wrong indices which I did not expect, I want
> to know how to set my renderer or actor without interpolation and shading
> to get the expected color.
>
> Thanks.
>
> --
> *Jaehyun Jang*
> Master's candidate
> School of Computing, KAIST
> 291, Daehak-ro, Yuseong-gu, Daejeon
> E3-1, 2413 STE
> Computer Graphics and Visualization Lab <http://cgv.kaist.ac.kr/>
> Resume <https://www.linkedin.com/in/silvesterjang> | Github
> <https://github.com/sysexits> | Personal
>
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-- 
Ken Martin PhD
Chairman & CFO
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065
518 371 3971

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