[vtkusers] Noise appears when extreme zooming in

[Ken Martin]

It could be a few things, we would really need more details to narrow it
down. Two things you can check

1) maybe a lighting issue, if you change your actors to be only ambient, no
diffuse, do you still see the issue?

2) maybe a zbuffer issue, If you zoom too far you can end up with bad (not
ideal) zbuffer clipping ranges. To narrow that down
 - are these Actors or Actor2D, what mapper are you using, do you have
overlapping or coincident geometry?
 - when you see the problem what is the value of
    - the camera's clipping range
    - camera's position, and focal point, distance
    - the bounds of your data

Generally you do not want any of those values to be really small or large
relative to the square root of the range a float can normally hold.





On Mon, Oct 17, 2016 at 5:28 PM, Patricio Palma C. <patriciop at gmail.com>
wrote:

> Hi experts, does anybody has any idea of what could causing the issue
> described in the previous email?
> Recently I have noted that something similar occurs on 3D structures when
> zooming in extremely to the structure and then rotating it. It appears
> a kind of pattern to generate the shadow of the face but as you rotate the
> structure the face begin to get noisy.
>
> My current setup is VTK git development branch using OpenGL2 as rendering
> backend. mesa 12.0.1 with AVX. I have also tried using mesa 11.2 and the
> results are the same.
>
> Thanks!
> Regards
> Patricio
>
> El Monday, October 3, 2016, Patricio Palma C. <patriciop at gmail.com>
> escribió:
>
>> Dear Experts
>>
>> I'm using VTK 7.1 (latest Git version) and Mesa 12.0 with AVX. I have an
>> application that display a 2D structure and some data on it. After zooming
>> in a couple times in the same spot of the structure it begins to appear
>> some noise over the 2D structure that increase after continuing zooming in.
>>
>> Is this a known issue? is there a way to solve/avoid this?
>>
>> I've attached some pictures showing how the noise appears while zooming
>> in.
>>
>> [image: Inline image 2]
>> [image: Inline image 3]
>> [image: Inline image 5]
>> [image: Inline image 6]
>>
>> --
>> Patricio Palma Contreras
>>
>
>
> --
> Patricio Palma Contreras
>
>
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-- 
Ken Martin PhD
Chairman & CFO
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065
518 371 3971

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