Volume rendering structured grid data...

[Joey Mukherjee]

> I need to volume render scalar data lying on a structured grid.  I've
> searched the archived e-mail list and looked at the Vtk documentation
> (book, pamphlet, and man page).  From this I've determined that two
> techniques have been suggested in the past:
> 
>    * Resample/splat the data into a structured points form, e.g.
>      "financialField.tcl" and go from there
>    * Slice through the grid, creating planes of polygons, and render
>      these back to front with appropriate colors and opacities, e.g.
>      "combVol.tcl"

I don't know how to do what you explicitly asked for, but since you asked for 
comments, I'll give you my experiences with roughly the same data.

We thought we wanted volume rendering and all we really needed was creating the 
iso-surfaces.  The atmospheric data we were looking at would create some shapes 
in the data, but we were having problems with the resample/splatting that you 
are seeing.  

What we ended up doing was just creating the iso surfaces with a 
vtkContourFilter and that produced some nice plots.  I then offered the user the 
ability to cut plane the data so they could truly see inside the shells.  By 
modifying the number of contours to generate, the user could generate more/less 
shells.

This was good enough and could handle a greater variety of data.  Just my 
experience, but wanted to let you know you weren't alone!  :-)

Joey

+--------------------------------------------------------------------------+
+     Joey Mukherjee                     "I am amused by the simplicity    +
+      joey at swri.org                      of this game.  Bring me your     +
+  http://www.space.swri.edu/~joey        finest meats and cheeses."       + 
+                                                                          +
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