[vtk-developers] Rendering scalar data with NaNs

[Moreland, Kenneth]

Alan,

As I recall, in your case you were using the ParaView plot over line filter, which internally uses a probe filter with a line source, and then running the results through an integration filter.  These changes do not touch any of those classes and should therefore have no effect.  These changes only effect the classes that convert scalars to colors for rendering.

-Ken


On 8/23/10 4:36 PM, "Scott, W Alan" <wascott at sandia.gov> wrote:

What would happen if the following occurs (real problem I worked on a few weeks ago) - a user wants to model a exhaust plume from a power plant.  The model does not go down to the ground.  The user then wanted to plot with line from OUTSIDE of this space , through this space, and out the other side (which ended up partially filled with nans - I am not sure if by ParaView, or his simulation code).  Would all of this data have color now, or would it stay transparent?

Alan


From: vtk-developers-bounces at vtk.org [mailto:vtk-developers-bounces at vtk.org] On Behalf Of Moreland, Kenneth
Sent: Monday, August 23, 2010 4:30 PM
To: VTK Developers
Subject: [vtk-developers] Rendering scalar data with NaNs

I've recently run into an issue with rendering fields with NaN values in it.  In this case, the data comes from a simulation that intentionally writes out NaN values, which have a significant meaning.  The problem is that the current VTK rendering classes have no control over what color the NaN values map to, and I have noticed that different hardware maps them differently.

Thus, I propose making the changes in the attached patches (created with git-format-patch).  First, a NanColor was added to vtkLookupTable (as a 4-tuple RGBA) and added to vtkColorTransferFunction (as a 3-tuple RGB) so that these respective lookup tables would return a specific color for NaN.  Next, vtkScalarsToColorsPainter was modified to use a 2D texture map that uses the second dimensions to distinguish between real and NaN values.  I also added a test for rendering these NaN values along with the other non-finite -INF and INF values.

Does anyone object to these changes, or do they seem reasonable to put into VTK?

-Ken

   ****      Kenneth Moreland
    ***      Sandia National Laboratories
***********
*** *** ***  email: kmorel at sandia.gov
**  ***  **  phone: (505) 844-8919
    ***      web:   http://www.cs.unm.edu/~kmorel



   ****      Kenneth Moreland
    ***      Sandia National Laboratories
***********
*** *** ***  email: kmorel at sandia.gov
**  ***  **  phone: (505) 844-8919
    ***      web:   http://www.cs.unm.edu/~kmorel

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtk-developers/attachments/20100823/aea66284/attachment.html>