[vtkusers] Glitch in rendering when using vtkGPUVolumeRayCastMapper in 7.0.0

[Elvis Stansvik]

2016-05-26 15:17 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> 2016-05-26 15:03 GMT+02:00 Andras Lasso <lasso at queensu.ca>:
>
>> Maybe you’ve forgot to set the camera clipping range.
>>
>
> Hm, I realize I wasn't clear: The problem occurs only with the GPU mapper,
> not with the software based one. So I don't think it's a clipping range
> problem (since then it would show up in the software mapper as well). I've
> also tried changing my clipping range and the effect is the same.
>
> It occurs no matter how zoomed in/zoomed out I am, and seems to more have
> to do with the angle I'm viewing the volume from.
>

Bah, my camera was actually positioned inside the volume. Moving it outside
to a "safe distance" and the problem is gone.

Elvis


>
> Elvis
>
>
>>
>>
>> Andras
>>
>>
>>
>> *From: *Elvis Stansvik <elvis.stansvik at orexplore.com>
>> *Sent: *May 26, 2016 08:29
>> *To: *VTK Users <vtkusers at vtk.org>
>> *Subject: *Re: [vtkusers] Glitch in rendering when using
>> vtkGPUVolumeRayCastMapper in 7.0.0
>>
>>
>> 2016-05-26 14:01 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>>
>>> 2016-05-26 13:46 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>
>>> :
>>>
>>>> Hi all,
>>>>
>>>> When I view my volume from certain angles, there are glitches in the
>>>> rendering when using vtkGPUVolumeRayCastMapper , see attached screenshots
>>>> when the glitch is occurring and when it is not.
>>>>
>>>> Has anyone seen this behavior and know what the problem might be? This
>>>> is on Intel HD 4400 graphics.
>>>>
>>>
>>> If it's not quite clear, the glitch is at the bottom of the first
>>> screenshot, where an are of the volume is not visible.
>>>
>>
>> An observation: I had the following to enable parallell projection in my
>> code:
>>
>>     self.camera.ParallelProjectionOn()
>>
>> If I remove this line, so that perspective projection is used instead,
>> the glitches disappear.
>>
>> This is not a solution, since I need to use parallell projection, but
>> maybe it's a clue to the problem?
>>
>> Elvis
>>
>>
>>> From certain angles the volume disappears almost completely.
>>>
>>> Elvis
>>>
>>>
>>>>
>>>> I would love to be able to use the GPU volume mapper since it's so much
>>>> faster than the software one.
>>>>
>>>> Thanks,
>>>> Elvis
>>>>
>>>
>>>
>>
>
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