[vtk-developers] UseJitteringOn() has no effect in 7.1.0.rc1

[Elvis Stansvik]

2016-10-14 17:14 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
> Den 14 okt. 2016 4:39 em skrev "Aashish Chaudhary"
> <aashish.chaudhary at kitware.com>:
>>
>> Based on the video its hard to say if it is the wood grain I am seeing or
>> something else is going on. Can you send a high-res static picture?
>
> I'm traveling at the moment, but I'll make a close-up screenshot as soon as
> I'm stationary.

Attaching a screenshot showing the effect. It's easiest to see in the
central close-up view.

I'll make a small test case as soon as I can.

Elvis

>
> The effect I'm seeing at least has the distinct look of wood grains :)
>
> Elvis
>
>>
>> @Alvaro, it would be good to look at the jittering code carefully as well.
>>
>> - Aashish
>>
>> On Fri, Oct 14, 2016 at 9:54 AM Alvaro Sanchez
>> <alvaro.sanchez at kitware.com> wrote:
>>>
>>> Hi Elvis,
>>>
>>> the mapper uses a vtkPerlinNoise instance to generate the jitter noise
>>> and as far as I know there are currently no knobs exposed to tweak the
>>> amount of ray perturbation.  Are you using the GL2 backend?  It would also
>>> be good to know what features are active along with ray jittering (multiple
>>> components, etc.), so if you could provide some sample data or code would be
>>> very helpful.
>>>
>>> Thanks!
>>> Alvaro
>>>
>>> On Fri, Oct 14, 2016 at 3:47 AM, Elvis Stansvik
>>> <elvis.stansvik at orexplore.com> wrote:
>>>>
>>>> Hi all,
>>>>
>>>> I updated our product to use VTK 7.1.0.rc1, as I was interested in
>>>> trying out vtkGPUVolumeRayCastMapper::UseJitteringOn() to get rid of
>>>> some woodgrain effects we're suffering from in our volume rendering
>>>> (mostly when the volumes are rendered very opaque).
>>>>
>>>> But turning the option on seems to have little to no effect. This is
>>>> the result with the option on:
>>>>
>>>>     https://dl.dropboxusercontent.com/u/22350696/out.ogv
>>>>
>>>> It looks about the same to me as it does with the option off.
>>>>
>>>> Are there any knobs for this option? How does it determine how much to
>>>> perturbate the rays?
>>>>
>>>> Thanks for any advise.
>>>>
>>>> Elvis
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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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