[vtkusers] volume data

[Ross Eldridge]

Vlad-

At the moment, all you can volume render in VTK are vtkImageData (and 
its subclasses) or a vtkUnstructuredGrid.  If possible, I would have 
tried to have your data as a vtkImageData (of which vtkStructuredPoints 
is a subclass), as using a vtkVolumeRayCastMapper (which only takes 
ImageData) is one of the faster methods of volume rendering.

If your data is in a structured grid, I would suggest converting it to 
an unstructured grid using vtkDataSetTriangleFilter.  Once you have a 
vtkUnstructuredGrid, you should be able to volume render it using a 
vtkProjectedTetrahedraMapper, which volume renders unstructured grids.  
As long as your data isn't too large, you should be able to volume 
render it easily.

-Ross

Vlad - Andrei Lazar wrote:
> Hey,
>
> Thanks for the very quick reply. Indeed it does not work very well 
> with glyphs. Trying now to modify the example in the VolumeRendering 
> directory. The problem is that my data is a StructuredGrid and 
> vtkVolumeRayCastMapper takes in a StructuredPoints at most. Is there a 
> way to convert a structuredGrid to StructuredPoint?
>
> Also tried using the vtkVolumeTextureMapper2D but when I call the 
> renderer TCL seg faults.
>
> Any easy ways out?
>
>
> Vlad
>
>
>
>
>
>
> Ross Eldridge wrote:
>> Hey Vlad,
>>
>> Instead of using cuts and isosurfaces, have you tried using a volume 
>> renderer on your data?
>>
>> If you really want to use glyphs, you'll want to adjust your 
>> vtkPolyDataMapper to do what you want.  To do that, set your mapper's 
>> lookup table to a new vtkLookupTable you create, and set whatever 
>> color ranges and alpha range (opacity) you want (don't forget to set 
>> your lookup tables scalar range using SetRange).  Of course, this is 
>> limited to a linear change in opacities, but hopefully it's what 
>> you're looking for.
>>
>> -Ross
>>
>>
>> Vlad - Andrei Lazar wrote:
>>
>>> Hello,
>>>
>>> I am trying to visuzlize 3D volume data. As it is rather hard to see 
>>> anything using cuts or isosrufaces, I have to come up with a new way.
>>>
>>> My idea was to place a glyph at each data point and make the opacity 
>>> of the glyph proportional to the value in that voxel. So far I did 
>>> not manage to do such a thing (the documentation is not all that 
>>> great I have to say...).
>>>
>>> Is there an easy way to do such thing?
>>>
>>> Best regards,
>>> Vlad
>>> ------------------------------------------------------------------------ 
>>>
>>>
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