[vtkusers] shading bug in vtk 6.2?

[marcin.krotkiewski]

I have attached the dataset and a simple MATLAB script that demonstrate 
the problem. Java bindings are used in the script.
With the chosen fill light settings the artifact patches are almost 
black. They are visible on the high slope parts of the model.

Hope this helps,

Marcin


On 05/27/2015 02:58 PM, Aashish Chaudhary wrote:
> 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 <mailto: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.
> /
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