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

[Alvaro Sanchez]

Hi Elvis,

I found the root cause of this, the noise texture is not being correctly
sampled in the shader.  I will tag you on the MR once the patch is ready so
that you can try it out.

Cheers,

On Thu, Oct 20, 2016 at 1:30 AM, Elvis Stansvik <
elvis.stansvik at orexplore.com> wrote:

> 2016-10-20 5:46 GMT+02:00 Alvaro Sanchez <alvaro.sanchez at kitware.com>:
> > I ran your test program and I could reproduce the wood-grain artifacts
> you
> > see.  It seems to me that the jitter noise might need some tweaking.  I
> will
> > try a few things and investigate further, will let you know my findings.
>
> Thanks Alvaro.
>
> Elvis
>
> >
> >
> > On Wed, Oct 19, 2016 at 8:07 AM, Elvis Stansvik
> > <elvis.stansvik at orexplore.com> wrote:
> >>
> >> 2016-10-19 14:03 GMT+02:00 Alvaro Sanchez <alvaro.sanchez at kitware.com>:
> >> > Hi Elvis,
> >> >
> >> > thanks for the test case.  Sorry, I did not have time to run it yet
> but
> >> > I
> >> > will have a look at it today.
> >> >
> >> > It seems unlikely to me that the small data spacing is affecting
> >> > jittering.
> >> > I will come back to you after debugging a bit with your test case.
> >>
> >> Alright, no hurry. Thanks a lot for having a look.
> >>
> >> Elvis
> >>
> >> >
> >> > Cheers,
> >> > Alvaro
> >> >
> >> > On Wed, Oct 19, 2016 at 1:54 AM, Elvis Stansvik
> >> > <elvis.stansvik at orexplore.com> wrote:
> >> >>
> >> >> 2016-10-15 11:16 GMT+02:00 Elvis Stansvik
> >> >> <elvis.stansvik at orexplore.com>:
> >> >> > 2016-10-14 15:54 GMT+02:00 Alvaro Sanchez
> >> >> > <alvaro.sanchez at kitware.com>:
> >> >> >> 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.
> >> >> >
> >> >> > Hi again Alvaro,
> >> >> >
> >> >> > Here's a minimal test case including sample data (129 MB):
> >> >> >
> >> >> >     https://dl.dropboxusercontent.com/u/22350696/test_grain.tar.gz
> >> >> >
> >> >> > Build with:
> >> >> >
> >> >> >     cmake .
> >> >> >     make
> >> >> >
> >> >> > and run with:
> >> >> >
> >> >> >     ./test_grain rec-0300mm-0400mm.xml
> >> >> >
> >> >> > The result should be as in the attached screenshot.
> >> >>
> >> >> Anyone had time to run my test case? Are you seeing the same thing?
> >> >>
> >> >> Elvis
> >> >>
> >> >> >
> >> >> > Elvis
> >> >> >
> >> >> >>
> >> >> >> 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
> >> >
> >> >
> >> >
> >> >
> >> > --
> >> > 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
>



-- 
Alvaro Sanchez
Kitware, Inc.
Senior R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4901
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