[vtkusers] Multiple volumes rendering with vtkGPUVolumeRayCastMapper or similar

Sat Aug 27 20:03:23 EDT 2016

I'm glad it worked out.

Cheers,

On Aug 26, 2016 12:12 PM, "amdelaossa" <adelaossa at gmail.com> wrote:

> Hello Álvaro,
>
> It works!
> Rendering multiple overlapping data volumes with the same grid is possible
> with vtkGPUVolumeRayCastMapper.
> Using numpy arrays was easy to gather the different 3-dimensional data
> arrays together by adding a 4th index to the combined array.
> The volume properties can be set independently for each one of the
> components.
> Thanks for the help!
>
> Best regards,
> Alberto
>
>
> On 26 Aug 2016, at 15:55, amdelaossa <adelaossa at gmail.com> wrote:
>
>
> On 26 Aug 2016, at 15:43, Alvaro Sanchez <alvaro.sanchez at kitware.com>
> wrote:
>
> It is great to read that you are working on this feature for future
>> releases of VTK.
>> I think that it will be very useful for many people.
>> In the mean time I would like to try your proposed approach of defining
>> multiple components in one volume.
>> Let me ask you something:
>> If data1, data2, data3 are my three independent three-dimensional data
>> arrays, should I merge them first in a four-dimensional array where the
>> first index is the component index?
>>
>>
> You should merge them in a three-dimensional array (each component being
> dataN).  Checkout TestGPURayCastTwoComponentsIndependent, that could
> serve you as an example.  Going back to your initial question though, as
> Elvis pointed out, if your volumes are not overlapping you could create
> instead several vtkVolumes (each with its own mapper), this should also
> work.
>
>
>
> My volumes are overlapping but they are defined in the same (regular)
> grid.
> So I need to use the multi-component trick.
> However I still do not understand the format…
> Lets say that I have two 3D arrays data1 and data2 with identical number
> of components in each direction, i.e.  data1(Nx,Ny,Nz) and data2(Nx,Ny,Nz).
> Should merge them into another array which would look like this:
> data(2 * Nx, Ny, Nz)
> with data(i,j,k) = data1(i,j,k) for i<Nx and
> data(i,j,k) = data2(i-Nx,j,k) for i>=Nx
>
> Is that right?
>
> Thanks!
> Alberto
>
>
> Could you give an rough estimation of when multiple volumes rendering
>> with vtkGPUVolumeRayCastMapper will be available in VTK?
>>
>>
> My best guess would be VTK 8.
>
>
>
> On Fri, Aug 26, 2016 at 6:39 AM, amdelaossa <adelaossa at gmail.com> wrote:
>
>> Hi Álvaro,
>>
>> Thanks a lot for your prompt answer!
>> See my comments below.
>>
>> 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.
>>
>>
>> It is great to read that you are working on this feature for future
>> releases of VTK.
>> I think that it will be very useful for many people.
>> In the mean time I would like to try your proposed approach of defining
>> multiple components in one volume.
>> Let me ask you something:
>> If data1, data2, data3 are my three independent three-dimensional data
>> arrays, should I merge them first in a four-dimensional array where the
>> first index is the component index?
>>
>> With regards to the solution you mentioned (https://github.com/bozorgi/VT
>> KMultiVolumeRayCaster), 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.
>>
>>
>> Alright. However this solution is currently not useful to me since it was
>> implemented for VTK 5 (I think) and it fails to compile against VTK 7.
>> So I am temporarily stuck here. I’d like to try your approach with the
>> multi-components…
>>
>> Could you give an rough estimation of when multiple volumes rendering
>> with vtkGPUVolumeRayCastMapper will be available in VTK?
>>
>> Thanks a lot!
>>
>> Regards,
>> Alberto
>>
>>
>> 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
>>> <http://plasma.desy.de/research/simulation_and_theory/index_eng.html> 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
>>
>>
>>
>
>
> --
> Alvaro Sanchez
> Kitware, Inc.
> Senior R&D Engineer
> 21 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4901
>
>
>
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