[Paraview] Best file format for volume rendering in ParaView?

[Christoffer Green]

Hello

Thank you for the suggestions.

The use case is that I am currently writing an application (based on
ParaView) that is going to be used by doctors/researchers for visualizing
MRI data of blood flow (some more information can be found here:
http://www.jcmr-online.com/content/14/S1/W14 ). This means that the user
has some data files (volumes of velocity data, 2d image planes, none of the
data is axis aligned, all of it overlapping) and they need to get this data
in to the application and I am currently trying to figure out what the
recommended way of doing this would be. I can not rely on the users having
any deep knowledge of ParaView, 3d math or even above basic general
computer skills so asking them to write macros or manually rotating the
data might not work well :)

The data->cleantogrid->volume render workflow sounds interesting. My
current problem with it (as well as using mergeblocks instead of
cleantogird) is that it appears to take about 8 hours to produce a result
that way (I do not know what that result is yet since I have not seen it
through to the end). This is off course unacceptably slow but perhaps this
is a bug?

But if I understand you correctly you are saying that unstructured grid is
the data format that would be best for this. Is there any file format that
when imported is an unstructured grid by default and would doing it that
way speed things up massively?

BR/ Christoffer

On Tue, May 22, 2012 at 3:39 PM, Berk Geveci <berk.geveci at kitware.com>wrote:

> What is your end goal? Volume rendering a collection of MRI volumes
> (together? non-overlapping?) that may not be axis aligned? One way of doing
> this in ParaView would be to convert them to unstructured grid (by using
> clean-to-grid for example) but this comes at a large memory overhead and
> performance overhead. The simpler and more efficient way of doing it is to
> load each MRI volume as a separate image data and then use the
> Transformation setting from the Display panel to position and orient them
> as necessary. It would pretty straightforward to write a macro to do all of
> this automatically given a particular file.
>
> On Mon, May 21, 2012 at 7:57 AM, Christoffer Green <
> christoffer.green at gmail.com> wrote:
>
>> Hello
>>
>> What are your thoughts on the best file format to use when doing volume
>> rendering in ParaView?
>>
>> I have been trying out the ensight format and the vtk format and find
>> them less then ideal, is there anything better?
>>
>> Findings for ensight:
>> ParaView does not appear to support volume rendering of ensight files due
>> to it not supporting volume rendering of multi-block datasets and the
>> ensight reader always imports things in multi block mode. There are ways to
>> get around this (tetrahedralize together with calculator filter) but the
>> end results appear to be extremely slow when volume rendering.
>>
>> Findings for vtk:
>> Importing a volume of data as image data and volume rendering it works
>> well but image data in the vtk format must always be aligned to the global
>> orthogonal (x, y, z) axes so it cannot be rotated. Since we have multiple
>> data files that all must be positioned and rotated in a scene (MRI volumes
>> and image planes) this makes things uncomfortable. There is a transform
>> filter in ParaView but after applying it to image data it changes the data
>> type to curvalinear grid which ParaView cannot volume render.
>>
>>
>> What are the alternatives?
>>
>> BR/ Christoffer
>>
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