[vtkusers] PolyData rendering problem

[Aashish Chaudhary]

On Thu, Nov 14, 2013 at 1:01 AM, Frank Gao <Frank.Gao at guidemia.com> wrote:

> Hi Aashish, David,
>
>
>
> I found out some old posting, and got a clue that the code can be
> RenderWindow()->SetPolygonSmoothing() and
> RenderWindow()->SetMultiSamples(). Did some test and found out they can not
> be used together. Only SetMultiSamples() will solve the problem. I tried
> SetMultiSamples(8) and SetMultiSamples(2). Both worked fine. I have no idea
> which one we should use, and what’s the impact.
>

Don't use polygon smoothing that's the old way (
http://www.gamedev.net/topic/107637-glenablegl_polygon_smooth/)

Can you please confirm this is the right thing to do? And what number
> should we use in SetMultiSamples?
>

I believe VTK does this (http://www.opengl.org/wiki/Multisampling) the more
samples you have the poorer the performance you will get.  However, if your
data is not that big, then I would suggest set it to 8 if not then 4 should
be good enough.

>

>
>
> Best regards,
>
> Frank
>
>
>
> *From:* vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] *On
> Behalf Of *Frank Gao
> *Sent:* Wednesday, November 13, 2013 9:06 PM
> *To:* 'Aashish Chaudhary'
>
> *Cc:* 'VTK Users'
> *Subject:* Re: [vtkusers] PolyData rendering problem
>
>
>
> Hi Aashish, David,
>
>
>
> Yes it is confirmed that the Antialiasing option is the reason. With
> either preference setting, when this one is off, we will see the problem.
> Setting antialiasing by 2x or 4x does not make noticeable difference. So my
> guess is that setting the Antialiasing will fix the problem, but we are not
> sure where and how is the best fix. Could you please shed some lights on
> this?
>
>
>
> Please see the following for a sample model.
>
> https://www.dropbox.com/s/f4dnywwcohlrvko/polydata_rendering_case.stl
>
>
>
> Best regards,
>
> Frank
>
>
>
> *From:* vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org<vtkusers-bounces at vtk.org>]
> *On Behalf Of *Aashish Chaudhary
> *Sent:* Wednesday, November 13, 2013 6:01 AM
> *To:* Frank Gao
> *Cc:* VTK Users
> *Subject:* Re: [vtkusers] PolyData rendering problem
>
>
>
> Can you try this experiment:
>
>
>
> Keep the setting to performance but just turn on the Antialiasing if it is
> possible to change that setting individually? There you will find options
> as well. Try different options and let us know if you see the difference?
>
>
>
> It could be either: z buffer precison issue or antialiasing issue if there
> is nothing special about your dataset.
>
>
>
> Also, can you send us this dataset?
>
>
>
> - Aashish
>
>
>
>
>
> On Tue, Nov 12, 2013 at 11:57 PM, Frank Gao <Frank.Gao at guidemia.com>
> wrote:
>
> Hi David,
>
>
>
> I did a comparison between the nVidia card settings, and found out the
> differences with “Performance” and “Quality” preference. Please see the
> document below.
>
>
>
>
> https://www.dropbox.com/s/vwdgj44zz6y3w6w/nVIdiaCard_Setting_difference.docx
>
>
>
> I am assuming there are some OpenGL calls to implement the difference, but
> don’t really know what to do. Hope this can provide some clues.
>
> Best regards,
>
> Frank
>
>
>
> *From:* vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] *On
> Behalf Of *David E DeMarle
> *Sent:* Tuesday, November 12, 2013 4:43 PM
> *To:* Frank.Gao at guidemia.com
> *Cc:* VTK Developers; VTK Users
> *Subject:* Re: [vtkusers] PolyData rendering problem
>
>
>
> What is the world space size of the triangles? Are they small enough to
> push the limits of GL float precision?
>
>
> David E DeMarle
> Kitware, Inc.
> R&D Engineer
> 21 Corporate Drive
> Clifton Park, NY 12065-8662
> Phone: 518-881-4909
>
>
>
> On Tue, Nov 12, 2013 at 6:10 PM, Frank Gao <Frank.Gao at guidemia.com> wrote:
>
>
>
> Hi All,
>
>
>
> We are having some problems with the surface rendering in VTK. If the
> users don’t set their graphics card preference to “Quality”, the surface
> rendering will show a lot of “ghost” lines between the triangles, but they
> are not the polydata edges. Completely display artifact. When the triangles
> are small, this is much more obvious. I places a picture in the following
> link. The left one has problem. The right one is when preference is set to
> “quality”.
>
>
>
> https://www.dropbox.com/s/1kvpzia57uggist/vtk_polydata_rendering_case.PNG
>
>
>
> Because of this we have to tell the users to change their graphics card
> setting. Is this something we can do in the code? Thanks a lot in advance.
>
>
>
> Regards,
>
> Frank Gao
>
>
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> --
> | Aashish Chaudhary
> | R&D Engineer
> | Kitware Inc.
> | www.kitware.com
>



-- 
| Aashish Chaudhary
| R&D Engineer
| Kitware Inc.
| www.kitware.com
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