[vtkusers] shading bug in vtk 6.2?

[Aashish Chaudhary]

Looks like a bug but hard to tell without a sample code that can replicate
this behavior on other machines.

- Aashish

On Wed, May 27, 2015 at 8:00 AM, marcin.krotkiewski <
marcin.krotkiewski at gmail.com> wrote:

>  Hi,
>
> I have a problem with shading in VTK 6.2 when using OpenGL2. The problem
> is visible when using lightkit, but not with simple scene light. I have
> attached pictures that demonstrate the problem.
>
> - model.jpg shows the 3D surface I am looking at - three combined
> gaussians.
> - shading_flat.jpg and shading_gouraud.jpg show a view from below at a
> place in the shadows, with steep surface slope. Both pictures are taken at
> the same camera position.
>
> shading_flat.jpg shows a strange patch that seems to me is a shading
> artifact. In contrast, shading_gouraud.jpg shows a nice, smooth gradient in
> the shadows. I have tested my code using vtk 6.1 and the result is
> different, i.e., similar to that shown in shading_gouraud.jpg.
>
> It seems also that the artifact is not there (or not visible) when
> lightkit is switched off. I have played around and I think it is caused by
> the fill light in the lightkit. Depending on the position of the fill light
> I can make this artifact patch all black.
>
> Could this be a bug related to the new OpenGL2 rendering engine?
>
> Thanks,
>
> Marcin
>
>
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-- 



*| Aashish Chaudhary | Technical Leader         | Kitware Inc.            *
*| http://www.kitware.com/company/team/chaudhary.html
<http://www.kitware.com/company/team/chaudhary.html>*
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