[vtkusers] [vtk-developers] [vtk-users] OpenGL2 - GPU Volume Rendering performance

Mon Oct 26 15:12:11 EDT 2015

Simon,

I used your dataset on paraview master as of today on my Linux box running
Ubuntu 14.04 and NVIDA Quadro card and I am getting about 15-20 FPS with
shading on with 1920x1080 resolution.

Are you on the proper 4.4 or using RC1/RC2? I checked the shading
performance fix was in 4.4 but not in RC's. I don't have access to Windows
box right away but I will try there too.

NOTE: You might get multiple emails because of the attachment size issue.
Sorry about that.

Thanks,

On Mon, Oct 26, 2015 at 2:45 PM, Aashish Chaudhary <
aashish.chaudhary at kitware.com> wrote:

>
>
> On Mon, Oct 26, 2015 at 2:13 PM, Simon ESNEAULT <simon.esneault at gmail.com>
> wrote:
>
>> Hello Aashish,
>>
>> Thanks for the quick answer
>> We are using a vtkImageData, 512x512x591 with short element (you can find
>> the dataset here : https://www.dropbox.com/s/ptqwi0ebv75kt35/volume.zip).
>> So I think it's all about GPU volume raycast mapper.
>> The new mapper does bring low resolution, but when compared to the old
>> one, it seems less "low resolution" during interaction than the old one
>>
>
> Right, so that's why its not a exact comparison. What happens is that
> depending on what is interactive, (you can set the desired update rate in
> VTK, not exposed in ParaView I believe),  it will do interactive but with
> higher resolution (smaller sample distance).  If they both have the same
> sample distance, then the new mapper should out perform the old one,
> however, there is another thing we need to consider here which is shading.
>
>
>> Shading is enabled, gradient opacity disabled
>>
>
> Can you disable the shading and see if now they both (opengl1 and 2)
> equally better? We already pushed a fix for it but not sure if that you
> have in your build.
>
>>
>> Don't know if you need a minimal example, but I believe the GPURenderDemo
>> used with this dataset is enough to highlight the slow down.
>>
>
> Yes, I will use this dataset. Thanks.
>
>>
>> Thanks
>> Simon
>>
>>
>> 2015-10-26 18:57 GMT+01:00 Aashish Chaudhary <
>> aashish.chaudhary at kitware.com>:
>>
>>> Also,
>>>
>>> Do you have shading enabled? We fixed a bug with shading that was
>>> causing the slow performance a while back. I don't remember if that was
>>> included in 4.4 or not ( I can check ).
>>>
>>> - Aashish
>>>
>>> On Mon, Oct 26, 2015 at 1:53 PM, Aashish Chaudhary <
>>> aashish.chaudhary at kitware.com> wrote:
>>>
>>>> Simon,
>>>>
>>>> What kind of dataset you are using? Depending on the data type you
>>>> might be using
>>>> the GPU one or the unstructured renderer. The performance we measured
>>>> is related to the GPU ray cast mapper
>>>> and will apply only to the vtkImageData inputs.
>>>>
>>>> Also, helpful would be is if you can tell if the new mapper is bringing
>>>> low resolution when you interact with the volume (and whether or not it
>>>> happens with old mapper).
>>>>
>>>> Thanks,
>>>>
>>>>
>>>> On Mon, Oct 26, 2015 at 1:47 PM, Simon ESNEAULT <
>>>> simon.esneault at gmail.com> wrote:
>>>>
>>>>> Hi All,
>>>>>
>>>>> We are trying to make the switch to the new OpenGL2 backend for our
>>>>> application, and although the switch was easy (thanks for not breaking the
>>>>> API ;) ), we can see a significant slowdown on the GPU volume rendering
>>>>> part, especially during interaction. Typically we dropped from 15/20 fps to
>>>>> 7/8 fps, on the same machine (Win32, Nvidia Quadro K420), with the same
>>>>> code around.
>>>>>
>>>>> This slow down can be seen in ParaView, if you compare the latest 4.4
>>>>> OpenGL2 build with the classic 4.4 build while volume rendering a big
>>>>> enough volume (512^3)
>>>>>
>>>>> The blog post here
>>>>> http://www.kitware.com/blog/home/post/976
>>>>> claims that the new GPU volume rendering implementation should be
>>>>> faster than the old one, is there some more detailed explanation somewhere
>>>>> ? Are there some important parameters that can make the difference ?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Simon
>>>>>
>>>>> PS : The polygonal rendering seems a lot faster with the new backend !
>>>>>
>>>>> --
>>>>> ------------------------------------------------------------------
>>>>> Simon Esneault
>>>>> Rennes, France
>>>>> ------------------------------------------------------------------
>>>>>
>>>>> _______________________________________________
>>>>> Powered by www.kitware.com
>>>>>
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>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>>
>>>>
>>>>
>>>> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.
>>>>   *
>>>> *| http://www.kitware.com/company/team/chaudhary.html
>>>> <http://www.kitware.com/company/team/chaudhary.html>*
>>>>
>>>
>>>
>>>
>>> --
>>>
>>>
>>>
>>> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.
>>>   *
>>> *| http://www.kitware.com/company/team/chaudhary.html
>>> <http://www.kitware.com/company/team/chaudhary.html>*
>>>
>>
>>
>>
>> --
>> ------------------------------------------------------------------
>> Simon Esneault
>> Rennes, France
>> ------------------------------------------------------------------
>>
>
>
>
> --
>
>
>
> *| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
> *| http://www.kitware.com/company/team/chaudhary.html
> <http://www.kitware.com/company/team/chaudhary.html>*
>

-- 

*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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