Help in reducing shimmering during animation

Help in reducing shimmering during animation

I'm working on an animation where the camera moves along a spline. The object it circles is comprised of two cylinders - the inside cylinder is slightly reflective. The outside cylinder has a transparent glass type surface.

During the animation, there is a very prominent shimmer / wobbling effect on the glass that most likely occurs from reflected light. I'm ok with this effect on the glass, but it also seems to be distorting the edges of the inside cylinder - and this has a unsettling, disturbing feel to it.

Can anyone offer advice on what parameters I might change to eliminate or reduce the shimmering on the edges of the insider cylinder?

sample animation can be downloaded from here:

http://www.gotlibdesign.com/rendersample/BodyBling.zip

In addition to various lights, these are the main settings I am using:

Camera:
Perspective: 38.717
antialising mode: edge
min samples: 1 x 1
max samples 4 x 4
Tolerance 0.050

Using HDRI tag

Radiosity:
intensity: 1
samples: 200
Diffuse Smatterings: 5
Specular Smatterings: 2

Using Fog tag

Outside Cylinder
The outside glass cylinder has a render tag with following checked:
visible for primary rays
filter textures

And it uses these material settings:

Color
ambient: 0
diffuse: 0

Specular
color: 3A3A3A

Emissive
Color: 3A3A3A

Reflection
color (white)
Intensity: 0300
angle: 0
samples: 16.0

Transparency
Color (white)
intensity: 0.950
index of refraction: 1.500
use alpha channel: not checked
fresnel: checked

Inside Cylinder
The inside glass cylinder has a render tag with following checked:
cast shadows
visible in radiosity
visible for primary rays
receive radiosity
filter textures

And it uses these material settings:

Color
color: 8A6B59
ambient: 0.970
diffuse: 0.950

Specular
color: black

Emissive
Color: black

bump mapping
intensity: 0.040

Reflection
color (black)
Intensity: 0.300
angle: 3.0
samples: 8.0

Transparency
none

Hi.
2 things:
A. make sure your glass cylinder has lot more longitudinal sections than the default parametric object; something above 65 will work just fine.
B. This effect can be caused by exporting the Quicktime movie in a somewhat scaled format rather than the rendered one.

Cheers
Frank

(Will post an example later.)

Thanks Frank.

Regarding your suggestion to increase the longitudinal section of the cylinder: I forgot to mention that the polygone objects have been made editable. Can I use Linear Subdivide to achieve the same fix?

Also - the sample I posted was a reduced QuickTime file. But the original movie was exported from Cheetah at the same dimensions set in the camera resolution. The shimmer is very noticeable in the original file as well. I even tried exporting the animation as a PNG image sequence but that too had the distortion.

pegot said:

Regarding your suggestion to increase the longitudinal section of the cylinder: I forgot to mention that the polygone objects have been made editable. Can I use Linear Subdivide to achieve the same fix?

Click to expand...

No - either a Catmull-Clark subdivision or the Subdivision Modifier will help you here.

pegot said:

Also - the sample I posted was a reduced QuickTime file. But the original movie was exported from Cheetah at the same dimensions set in the camera resolution. The shimmer is very noticeable in the original file as well. I even tried exporting the animation as a PNG image sequence but that too had the distortion.

Click to expand...

So it´s just the "low poly" mesh what is causing this and it will be an easy fix.
Here´s my quick hack on this with a glass parametric cylinder with 65 longitudinal sections.

Cheers
Frank

I see now that my problems might have been caused by (a) inexperience and (b) an unnecessarily complicated object - most certainly caused by the latter!

On closer inspection I realized my glass object has quite a number of modifications I had forgotten about, and these might also be the issue.

I used it in a boolean operation to give the glass some thickness while maintaining a hollow interior (I think I used two cylinders, one with a wider radius than the other - and to complicate things, they might have been of differing longitudinal sections).

This resulted in an object that, while it has a large number of longitudinal sections, is also triangulated.

Guess I should just try to recreate the object in a simpler manner, such as in your sample movie. I modeled it a ways back so this now forces me to re-evaluate my methods.

These are the things that really bites one during the learning process. You spend all this time modeling, texturing, and lighting a scene. And it might all work fine in a still render. But animation multiples the complexities of all these tasks tenfold!

Yes - that explains a lot.
I would go with a spline and lathe creator for the glass flacon - best to control everything; curvature, sections etc.

Cheers
Frank

All fixed :smile:

Thanks again!

I went with a tube polygone - will try a spline when I have more time.