[vtkusers] Volume rendering problem

[Ken Martin]

Some systems only support up to 4096 as a 3D texture dimension, maybe try
300x300x4096 -Ken

On Thu, Aug 11, 2016 at 8:44 AM, Elvis Stansvik <
elvis.stansvik at orexplore.com> wrote:

> 2016-08-11 13:26 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>
>> 2016-08-11 11:37 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>>
>>> 2016-08-11 11:18 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>
>>> :
>>>
>>>> Hi all,
>>>>
>>>> I'm wrestling with a volume rendering problem.
>>>>
>>>> I've set up a very basic pipeline that just renders a volume.
>>>>
>>>> As source it uses a custom reader I wrote that loads a volume from a
>>>> HDF5 dataset (float).
>>>>
>>>> It seemed to be working fine with the volume I had been testing with
>>>> (see attached works_fine.png), which was a 120x120x2000. In addition to the
>>>> the rendering itself, the screenshot shows a histogram plot I was using for
>>>> debugging, as well as some editor controls I use to modify the
>>>> color/opacity transfer function.
>>>>
>>>> I then tested with another volume which is larger (300x300x5000), but
>>>> apart from that has pretty much the same characteristic for its scalar
>>>> values as the first one, and all of a sudden I don't see anything. See the
>>>> attached not_working.png, which shows the setup using the problematic
>>>> volume.
>>>>
>>>> As you can in the histogram, there's a lot of voxel values roughly
>>>> around 1, much like in the first volume, so I would expect that with the
>>>> same transfer functions (black color, and an opacity ramp from 0.0,0.0 up
>>>> to 5.0,1.0), I should see _something_.
>>>>
>>>> I'm pretty sure I'm missing something basic here, but does anyone have
>>>> an idea why I get the expected rendering with my smaller volume, but not
>>>> with the bigger one?
>>>>
>>>> Thanks a lot for any advice!
>>>>
>>>
>>> Sorry, shortly after sending this I think I got one step closer to an
>>> explanation. The file from which I load this second, larger, volume is
>>> actually a concatenation of several files, and I just tried loading one of
>>> the files separately and it worked fine (the rendering looks as expected).
>>> So something is probably wrong in the script I use for concatenating HDF5
>>> files. I'll do some digging there.
>>>
>>
>> There seems to be nothing wrong with the concatenation script I'm using.
>> I've now tried creating smaller volumes by not concatenating the full set
>> of files, and up until a resulting volume of around ~2500x300x300 it works
>> okay, but if I extend the volume more than that, the rendering fails like
>> described previously. It's quite strange :/ And I don't think I'm hitting
>> some out-of-memory condition inside VTK, since it normally prints nice
>> errors and crashes if that happens.
>>
>
> I'm beginning to think that maybe I'm running out of graphics memory?
> Could this be a symptom of that?
>
> I've now created a minimal test case, and would very much appreciate if
> someone could try it out to see if they get the same problem:
>
> Download
>
>    https://drive.google.com/open?id=0B1a2u6qVxaL7M1B6bFhreE1RQW8
>
> and extract the .tar archive (162 MB since it includes two volumes). Then
>
>    cmake .
>    make
>    ./voltest working.hdf5
>    ./voltest not_working.hdf5
>
> For me, rendering of working.hdf5 works, but not rendering of
> not_working.hdf5. Is that the case also for you?
>
> The only difference between the two volumes is that not_working.hdf5 is
> slightly larger than working.hdf5 (2500 voxels high vs 2000). Apart from
> that they were both created in the same way.
>
> Thanks a lot in advance,
> Elvis
>
>
>> Elvis
>>
>>
>>> Elvis
>>>
>>>
>>>>
>>>> Elvis
>>>>
>>>> PS. If you're confused by the range of the vtkAxisActor that you see in
>>>> the screenshots, when comparing to the the volume sizes I stated above,
>>>> it's because my custom render currently hardcodes the spacing to 0.2. DS.
>>>>
>>>
>>>
>>
>
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-- 
Ken Martin PhD
Chairman & CFO
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065
518 371 3971

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