[vtkusers] Volume rendering

[Lisa Sobierajski Avila]

Hello Natraj,

Having binary data may be the problem. A central difference technique is 
used to generate normals - and with only 0's and 1's there are a very 
limited number of possible normals. Perhaps the "bad" lighting is caused by 
this.

Lisa


At 02:59 PM 9/27/2001, Natraj Iyer wrote:
>Hi,
>
>I am having problems in volume rendering a voxelized object. The
>lighting seems to be really bad. I tried adding lights but it does not
>help.. Does anyone have any suggestions on how to rectify this.. When I
>generate the isosurface using vtkContourFilter it works fine..
>
>My voxel.vtk file just contains 1's and 0's.
>
>I have to use vtkImageCast because VTK gives me an error saying Data
>Type 2 is unsupported.
>
>Thanks
>
>Natraj
>
>My tcl script is as follows:
>
>vtkDataSetReader areader
>    areader SetFileName voxel.vtk
>
>vtkImageCast reader
>reader SetOutputScalarTypeToUnsignedShort
>reader SetInput [areader GetOutput]
>
># Create transfer functions for opacity and color
>vtkPiecewiseFunction opacityTransferFunction
>     opacityTransferFunction AddPoint  0  0.0
>     opacityTransferFunction AddPoint  1  1.0
>
>vtkColorTransferFunction colorTransferFunction
>     colorTransferFunction AddRGBPoint       0.0 1.0 0.0 0.0
>     colorTransferFunction AddRGBPoint      1.0 0.0 0.0 0.3
>
># Create properties, mappers, volume actors, and ray cast function
>vtkVolumeProperty volumeProperty
>     volumeProperty SetColor colorTransferFunction
>     volumeProperty SetScalarOpacity opacityTransferFunction
>     volumeProperty ShadeOn
>     volumeProperty SetDiffuse 1.0
>     volumeProperty SetAmbient 0.3
>     volumeProperty SetSpecular 1.0
>     volumeProperty SetSpecularPower 100.0
>
>vtkVolumeRayCastCompositeFunction  compositeFunction
>
>vtkVolumeRayCastMapper volumeMapper
>     volumeMapper SetInput [reader GetOutput]
>     volumeMapper SetVolumeRayCastFunction compositeFunction
>
>vtkVolume volume
>         volume SetMapper volumeMapper
>         volume SetProperty volumeProperty
>
>vtkLight light1
>light1 SetPositional 1
>light1 SetPosition 15.0 15.0 15.0
>
>vtkLight light2
>light2 SetPositional 1
>light2 SetPosition -5.0 -5.0 -5.0
>
>vtkRenderer ren1
>vtkRenderWindow renWin
>     renWin AddRenderer ren1
>     renWin SetSize 300 300
>vtkRenderWindowInteractor iren
>     iren SetRenderWindow renWin
>     iren LightFollowCameraOn
>
>ren1 AddVolume volume
>ren1 SetBackground 1.0 1.0 0.9
>ren1 AddLight light1
>ren1 AddLight light2
>
>renWin Render
>
>
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