[Paraview] application specific questions

[Bond, Karina Paula Carvalho]

Thanks! Your responses have been very helpful. 
I will need a little bit of time to work on the LUT and file format suggestions you made. I might have more questions then. But I have a few things to try before that ..

Karina

-----Original Message-----
From: Utkarsh Ayachit [mailto:utkarsh.ayachit at kitware.com] 
Sent: Tuesday, April 24, 2012 12:15 PM
To: Bond, Karina Paula Carvalho
Cc: paraview at paraview.org
Subject: Re: [Paraview] application specific questions

Karina,

> ...And then you are saying I should be able to use the "LUT Editor" in Paraview individually for each of my files(*.vtk) after loading them in manually, right?

Yes. Also, is the scalar for each segment constant for that segment?
In that case you may want to name the scalar using the same name for all the segments but give each one a different scalar value. Then when you load it, you can color all segments using the same scalar array but specify a LUT that spans the range for scalar values provided by all segments.


> Can I use *.vtm to group a bunch of "unstructured grid" blocks of data? If yes, is there some advantage of using "Polydata" instead of "unstructured grid" for the segments?

Unstructured is just fine. vtm can support blocks comprising of unstructured datasets. Note that vtm requires  the blocks to be specified using the VTK-XML formats (and not legacy VTK) so you'll have to write *.vtu files for your segments.

> So if load my *.vtm file into Paraview, is there a quick way to select a different LUTs for each segment? OR will I have to manually extract each block and select a LUT? I can see how this might get cumbersome as the number of segments increase.

Alas, that's what you have to --- extract each one to color it. But if we're talking of a constant scalar for the entire segment, things might get easier by the solution I suggested earlier.

> I was actually hoping I could somehow specify the LUT in the vtk file. But you said earlier this is not recognized in Paraview, right? Any thoughts?

Yup, ParaView won't respect LUTs in the vtk file. But you can specify the color scalar (RGB) in the data directly. SImply create a scalar array that's of the type unsigned-char with 3 components and the color using that array. ParaView will still try to create a LUT by default, but on the display tab, you should then be able to uncheck "Map Scalars" and the colors specified in the data will be used directly. I am not sure I've expressed it clearly here, so let me if it isn't obvious.

> I am using v3.14.0. For the unstructured grid data , the volume rendering displays almost like a surface rendering while I am moving the mouse. And then there is a delay one I have settled on a position ( not pressing the  left-button on the mouse") and then I see the volume rendering.

Ah! You're using unstructured grid volume rendering. Yes, that'd do what you say. And here the delay is due to CPU. We only have CPU volume renderers, if I am not mistaken. Again, if your data is a structure data, I'd leave it as ImageData. It should perform much better.

Utkarsh