[vtkusers] How to convert float data to unsigned short for volume rendering, and a bug? in load filters

[Dr. Daniel James White PhD]

Hi All,

1)
I saw this load filter a while ago, but have just been been prompted to 
mention it.

On a red hat 8 linux box,
recent VTK CVS and MayaVi1.3  CVS snapshot 20031023

On trying to load any of the filters I get this error message
Exception
/usr/lib/python2.2/site-packages/mayavi/Main.py:487:
NameError :global name 'kw' not defined (in load_filter)

2) On my MacOSX machine where load filter works (also with recent VTK 
CVS and MayaVi1.3  CVS snapshot 20031023)
I have a .vtk file containing a 3D structured grid  of scalar float 
data from cryo Electron Microscopy of a virus.

Yes Prabhu, another application for MayaVi is 3D structures of large 
molecules such as viruses and ribosomes from cryEM!

Here is the file header

# vtk DataFile Version 2.0
hbcore2 17 parts 2Dec93                                     Dec  8 
14:31:48 199
BINARY
DATASET STRUCTURED_POINTS
DIMENSIONS 55 55 55
ORIGIN 0.000000 0.000000 0.000000
SPACING 1.000000 1.000000 1.000000
POINT_DATA 166375
SCALARS density float 1
LOOKUP_TABLE default

I made this .vtk file from a .mrc file using proc3d in the EMAN cryoEM 
data manipulation package.

I want to volume render with data with the volume module (and our 
experimental volumepro100 module which is working nicely so far..)
however the data is float, and has negative values (and positive ones), 
and does not work for ray casting with vtkRayCastMapper.

Some how I need to convert this to unsigned short? for volume rendering.

Iso surface works with the data as it is, but the transparency does not 
work on my linux box. It is either 100% or 0% transparent hen I move 
the opacity slider in the MayaVi isosurface module window. Transparency 
does work fine on the OSX machine.


Can I use a vtk filter from within MayaVi, perhaps "user defined 
filter" or one of the existing ones to make this data work for the 
MayaVi volume module?

cheers

Dan



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