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

[Alvaro Sanchez]

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.


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
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