[vtkusers] Noise appears when extreme zooming in

Tue Oct 18 01:01:48 EDT 2016

Hi Ken, experts,

   Thank you for the quick response.
Regarding point one, SetDiffuse(0.0) was applied to all actors, the
structure looks darker with no shadows, but the issue still occurs.

About point 2:
- the actor we use is derived from vtkQuadricLODActor
- and there are some overlapping geometries

Below is a image of the structure in the beginning. Clipping range,
position, focal point and distance are shown below
[image: Inline image 1]
Debug: Camera clipping range:  3.61282   4.44839
Debug: Camera position:  -1.93487   2.37646   2.48559
Debug: Camera focal point:  0.0543755   -0.0598546   0.0492757
Debug: Camera distance:  3.97849
Debug: Bounds : [  -0.100974  ,  0.296875  ,  -0.08  ]  [  0.08  ,  0  ,
 0.05  ]

After zooming in a bit, it appears a soft pattern of lines over the face of
the structure
[image: Inline image 2]
Debug: Camera clipping range:  3.61282   4.44839
Debug: Camera position:  -1.92875   2.37186   2.4952
Debug: Camera focal point:  0.0604954   -0.0644594   0.0588774
Debug: Camera distance:  3.97849
Debug: Bounds : [  -0.100974  ,  0.296875  ,  -0.08  ]  [  0.08  ,  0  ,
 0.05  ]

Finally after zooming in a couple of steps more, it appears noise/lines
over the face.
[image: Inline image 3]
Debug: Camera clipping range:  3.61282   4.44839
Debug: Camera position:  -1.92882   2.37202   2.49498
Debug: Camera focal point:  0.0604254   -0.0643013   0.0586621
Debug: Camera distance:  3.97849
Debug: Bounds : [  -0.100974  ,  0.296875  ,  -0.08  ]  [  0.08  ,  0  ,
 0.05  ]

It calls my attention that only position and focal point are being updated
after zooming in.

Thanks
Patricio

On Mon, Oct 17, 2016 at 8:21 PM, Ken Martin <ken.martin at kitware.com> wrote:

> 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
>>
>>
>> _______________________________________________
>> Powered by www.kitware.com
>>
>> Visit other Kitware open-source projects at
>> http://www.kitware.com/opensource/opensource.html
>>
>> Please keep messages on-topic and check the VTK FAQ at:
>> http://www.vtk.org/Wiki/VTK_FAQ
>>
>> Search the list archives at: http://markmail.org/search/?q=vtkusers
>>
>> Follow this link to subscribe/unsubscribe:
>> http://public.kitware.com/mailman/listinfo/vtkusers
>>
>>
>
>
> --
> Ken Martin PhD
> Chairman & CFO
> Kitware Inc.
> 28 Corporate Drive
> Clifton Park NY 12065
> 518 371 3971
>
> This communication, including all attachments, contains confidential and
> legally privileged information, and it is intended only for the use of the
> addressee.  Access to this email by anyone else is unauthorized. If you are
> not the intended recipient, any disclosure, copying, distribution or any
> action taken in reliance on it is prohibited and may be unlawful. If you
> received this communication in error please notify us immediately and
> destroy the original message.  Thank you.
>

-- 
Patricio Palma Contreras
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: step2.jpg
Type: image/jpeg
Size: 5141 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0007.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: zoom2.jpg
Type: image/jpeg
Size: 46634 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0008.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: zoom3.jpg
Type: image/jpeg
Size: 66880 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0009.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: step1.jpg
Type: image/jpeg
Size: 2217 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0010.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: step0.jpg
Type: image/jpeg
Size: 3073 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0011.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: step3.jpg
Type: image/jpeg
Size: 8251 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0012.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: zoom1.jpg
Type: image/jpeg
Size: 37655 bytes
Desc: not available
URL: <http://public.kitware.com/pipermail/vtkusers/attachments/20161018/cc79c92d/attachment-0013.jpg>