Hey, cool, I just tried that on some test data, and it looks like it might do 
the trick. I do have a rather large dataset, but I'll try both this and 
Sebastian's suggestion and see what happens. Thanks!

-Jeff


On Dec 13, 2010, at 15:31 , Berk Geveci wrote:

> What you need is to volume render cell data instead of point data. 
> Unfortunately, ParaView does not support volume rendering of cell data in 
> images. However, it supports volume rendering of cell data in unstructured 
> grids. Try this:
> 
> - Create a STRUCTURED_POINTS with cell data
> - Load it
> - Apply Clean to Grid
> - Volume render
> 
> I wouldn't recommend doing this if your volumes are going to become large.
> 
> -berk
> 
> On Mon, Dec 13, 2010 at 10:41 AM, Jeff Johnson <[email protected]> wrote:
> This is great, thanks Berk and Sebastien. Yes, I am trying to do volume 
> rendering. My dataset represents a 3D grid occupancy map, where each cell has 
> a specified likelihood of occupancy. I'd like to render that as a set of unit 
> cells, where the opacity is directly related to the likelihood of occupancy 
> (i.e., totally opaque means likelihood of 1, totally transparent mean 
> likelihood of 0). Does that make sense?
> 
> I did try STRUCTURED_POINTS for doing the volume rendering, and it's seems 
> close to what I'm looking for, but maybe I'm not setting it up quite right: 
> The coloring seems to radiate out from one side, and it also seems to bleed 
> out into neighboring cells. If I could get the color to radiate from the 
> center out (or just have the cell uniformly colored), and have the coloring 
> end at the cell boundaries, that would be perfect. I've attached a pic of 
> what I see.
> 
> Thanks again, guys.
> 
> -Jeff
> 
> 
> 
> 
> On Dec 13, 2010, at 07:22 , Berk Geveci wrote:
> 
> > Assuming that you are defining a uniform rectilinear grid, you need 
> > STRUCTURED_POINTS. As for defining opacity, what is your goal? To do volume 
> > rendering? Other than when using volume rendering, opacity does not have 
> > any effect.
> >
> > If you need to define an arbitrary set of cubes, you probably need an 
> > unstructured grid.
> >
> > Can you give us an example of your dataset and visualization you want to 
> > do? A picture maybe?
> >
> > -berk
> >
> > On Sun, Dec 12, 2010 at 10:15 AM, Jeff Johnson <[email protected]> wrote:
> > Thanks, but I'm totally new to the VTK file format and ParaView, and the 
> > documentation is not clear. It seems like the STRUCTURED_GRID geometry is 
> > the proper one for what I need, but I can find virtually no examples of 
> > it's use. For instance, if I want to specify a set of unit cubes from a set 
> > of points, do I do that in POINT_DATA or CELL_DATA? If I want to color them 
> > and set an opacity, where does that information go? The documentation says 
> > that a lookup table is a set of RGBA values that is associated with scalar 
> > data, but what does the scalar data represent, and how do I associated it 
> > with the cubes?
> >
> > -Jeff
> >
> >
> > On Dec 12, 2010, at 03:27 , Sebastien Jourdain wrote:
> >
> > > Hi Jeff,
> > >
> > > on the help page of vtk (http://www.vtk.org/VTK/help/documentation.html)
> > > you do have a link on the VTK file format.
> > > You should be able to find all the informations that you need here:
> > > http://www.vtk.org/VTK/img/file-formats.pdf
> > >
> > > Seb
> > >
> > > On Sat, Dec 11, 2010 at 8:44 PM, Jeff Johnson <[email protected]> wrote:
> > >> Hi all,
> > >>
> > >> I'm using ParaView to visualize a dataset, and I'm trying to generate an 
> > >> ASCII VTK file that will specify a set of voxels, where each voxel has 
> > >> an associated color and opacity. Does anyone have any suggestions for 
> > >> how I should format the file? It seems like this should be easy, but I 
> > >> can't make heads or tails of the documentation.
> > >>
> > >> -Jeff
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> 
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