[vtkusers] Re: vtkusers digest, Vol 1 #2035 - 18 msgs

[Dr. Daniel James White PhD]

Hi Janne,

try using the Mayavi VTK frontend, with the experimental volume module,
see the mayavi mailing list for this.

Dan

On Monday, August 25, 2003, at 04:52 PM, vtkusers-request at vtk.org wrote:

>
> Message: 2
> From: =?iso-8859-1?Q?H=E4m=E4l=E4inen_Janne?= <Janne.Hamalainen at hus.fi>
> To: "'vtkusers at vtk.org'" <vtkusers at vtk.org>
> Date: Mon, 25 Aug 2003 14:41:36 +0200
> Subject: [vtkusers] Blending two volumes
>
> Hi all,
>
> I have a following situation: I have two vtkImageData objects =
> (tomographic
> medical data) that I want to display using volume rendering. I would =
> want to
> blend them (as with vtkImageBlend), so that both objects would have
> different colors, e.g., so that I had a gray translucent data set and =
> inside
> that an opaque green area.=20
>
> I have done the same thing for 2D slices extracted from the volume by
> mapping the original intensity levels of the images to colors with
> vtkImageMapToColors (using a different vtkLookupTable for both) and
> combining the results with vtkImageBlend. The results can be shown =
> easily
> with 2D texture mapping. For 3D rendering this doesn't seem a possible 
> =
> way
> to do things. I can of course map the volumes to different colors and =
> blend
> them, but volume rendering seems to assume that the mapped data has no
> colors, but instead a vtkColorTransferFunction is used to map the =
> intensity
> levels. Different color transfers can be specified for each component =
> of the
> input data, but I don't understand how this is interpreted. Is it =
> simply
> that you can specify what component to use for volume rendering? And is
> there any way to use the original color components of the input =
> vtkImageData
> in volume rendering to get the desired effect?=20
>
> I also tried rendering (ray casting) the two volumes to a same scene =
> using a
> different color transfer for both, but the results weren't =
> satisfactory. The
> volume that was rendered last (it is inside the other volume) is not =
> veiled
> by the other translucent volume, but instead is shown as though it were
> outside it. The toggle IntermixIntersectingGeometry is on, although I =
> would
> guess that it hasn't any effect on volumes, right?
>
> If anyone 1. knows a way to volume render colored image data (or knows 
> =
> that
> it is not possible), or 2. knows if there is a way to render multiple
> volumes to a same scene so that overlapping parts are blended, I would
> gladly accept any information,
>
> -Janne
>
>
Dr. Daniel James White BSc. (Hons.) PhD
Cell Biology
Department of biological and environmental science
PO Box  35
University of Jyväskylä
Jyväskylä FIN 40014
Finland
+358 (0)14 260 4183 (work)
+358 (0)414740463 (mob)

http://www.chalkie.org.uk
dan at chalkie.org.uk
white at cc.jyu.fi