[vtkusers] Multiple volumes rendering with vtkGPUVolumeRayCastMapper or similar

Fri Aug 26 03:04:42 EDT 2016

2016-08-26 8:38 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> Den 26 aug. 2016 5:06 fm skrev "Alvaro Sanchez" <
> alvaro.sanchez at kitware.com>:
> >
> > Hi Alberto,
> >
> > as you have noticed, multi-volume rendering is currently not supported
> in the vtkGPUVolumeRayCastMapper.  If you are building VTK with OpenGL2
> however, it supports independent components so (depending on your use case)
> you might be able to render up to 4 volumes (one per component), provided
> you can arrange them in a four component array (this has the limitation
> that each component will need to have the same dimensions).  That said, we
> are working on giving support for multiple volumes in the next VTK release.
>
> I have to jump in and ask: I was under the impression that multiple
> volumes was supported, as long as they don't intersect eachother in 3D
> space? But you're saying it's not possible at all?
>
I found the mail by Aashish which led me to believe this was possible:

    http://public.kitware.com/pipermail/vtkusers/2016-February/094333.html

If it is actually possible, I have a question about the result I would get:
If I had multiple volumes in the same view (non-intersecting) and the
camera was positioned such that one of the volumes is in front of the other
relative to the camera. Would the obstructed voxels of the furthest volume
not be visible at all, or would I be able to see them "through" the nearest
volume?

Elvis

> If so I'm in a bit of trouble myself, as I was planning on doing that soon
> :(
>
> In my case I have multiple volumes (coming from different readers) that I
> want to render next to eachother (but not overlapping anywhere).
>
> If that's really not possible, I'll have to rethink my pipeline and
> redesign my custom reader to work with multiple files instead (and output a
> single volume). The problem with this is that I might want to show a volume
> that is larger than 2048 voxels in one dimension, which is not possible, at
> least not on intel, due to GPU texture size limitations (see my semi-recent
> thread about this). I had hoped that using multiple volumes would be a way
> to get around this.
>
> Thanks in advance,
> Elvis
>
> >
> > With regards to the solution you mentioned (https://github.com/bozorgi/
> VTKMultiVolumeRayCaster), you could use it temporarily if it would solve
> your problem better than fitting the volumes as independent components.  It
> seems to implement a similar approach as we would do (connecting various
> inputs/ properties to the mapper) so it should not be extremely difficult
> to migrate to the official implementation in the future.  I have not tried
> it myself but please do let us know if you have any remarks once you try
> it.  As far as I know, if the python bindings are not explicitly disabled
> for these new classes then they should be also wrapped.
> >
> > Regads,
> > Álvaro
> >
> >
> >
> >
> >>
> >> ---------- Forwarded message ----------
> >> From: amdelaossa <adelaossa at gmail.com>
> >> Date: Thu, Aug 25, 2016 at 10:00 AM
> >> Subject: [vtkusers] Multiple volumes rendering with
> vtkGPUVolumeRayCastMapper or similar
> >> To: vtkusers at vtk.org
> >>
> >>
> >> Dear all,
> >> we (a research team in DESY, Germany) are strongly interested in
> rendering multiple data volumes in the same view with VTK.
> >> We chose VTK for our 3D visualisation project on beam-plasma
> interactions due to its extended functionality and features,
> >> its open source character and because it is written in C++ with
> bindings for python.
> >> However, we will require to show multiple volumes in the same view
> (representing the data of different particle species in our simulations).
> >> We are currently using a vtkGPUVolumeRayCastMapper object for each data
> set, which is then connected to a vtkVolume.
> >> The different vtkVolume objects are then added to the vtkRenderer.
> >> We have tried to use different vtkRenderer objects for the different
> vtkVolumes,
> >> but still only the first volume on the first vtkRenderer is displayed.
> >>
> >> Searching in the web, we have found the following (potential) solution:
> >> https://github.com/bozorgi/VTKMultiVolumeRayCaster
> >> which is published here:
> >> http://www.ncbi.nlm.nih.gov/pubmed/24841148
> >>
> >> It consists on new vtk classes to handle multiple volumes rendering.
> >> As it might work well for our purposes, we would like to ask your
> opinion about this new classes.
> >> Are you planning to incorporate something like this in the official VTK
> distribution soon?
> >> If not, we will be interested in incorporating this new class into our
> personal VTK installation.
> >> Then the question is: Will be the python bindings automatically
> generated for these new classes?
> >>
> >> Thanks a lot for your support!
> >>
> >> Best regards,
> >> Alberto
> >>
> >>
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> >>
> >
> >
> >
> > --
> > Alvaro Sanchez
> > Kitware, Inc.
> > Senior R&D Engineer
> > 21 Corporate Drive
> > Clifton Park, NY 12065-8662
> > Phone: 518-881-4901
> >
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