View Full Version : custom object sampling /AA with MR

11 November 2005, 11:41 PM
using maya 6.5, the custom sampling overrides for MR in an object's shape node don't seem to be working properly... what i want is an entire scene that has min -1 max 1 samples, except for a few specific objects which should be min 0 max 2.

when i set these 0 2 values in the object's overrides, the object looks about ten times worse. ?

is this a bug in 6.5, and if so can someone confirm if its working in 7.0?

EDIT: ok I've just found this in the help: "Min Max Object Samples Limits: The values you select must be within the global sample limits". what the hell is the point of having an "override" if you have to increase the sampling of every other object in the scene..?? even after setting ranges in globals and sampling every object manually, i can't get the ideal settings i described above.

11 November 2005, 02:22 AM
The point is to raise the min level on the object over the other parts of the scene.

In Maya 6.5 the object samples min and max get translated to mental ray both set to the min. I believe it is fixed in Maya 7.

Also you can use default object min and max to do what you want.
For example, if we set the overall range to -1 1
default object samples to -1 0 and
object samples to 0 1

The object will span 0 to 1 samples and everywhere else will span -1 0.

Go here for more details and look at the last section:

11 November 2005, 03:12 AM
thanks for the reply - following that example i just did a test and unfortunately the results were not impressive :( the scene consisted of 3 balls. the settings were as follows:

Global AA Samples: Min -1 Max 2
Global Sample Defaults: Min -1 Max 1
Per Object Samples (on 1 ball): Min 2 Max 2 (Min 1 makes no difference).

Funny thing is all 3 balls look better with overrides off, and just setting Global AA Samples to 0 2, and it renders 3 times faster. ?

so either i'm doing something majorly wrong or the intergration of the per-object samples is lacking in 6.5.

11 November 2005, 04:30 AM
Francesca created a shader that fixes two bugs in Maya 6.5, and this is one of them. You can get it here:

You create a 'dummy' object (just a cube or something) and attach this shader as a Geometry Shader to it. You can then use the fixes the shader provides. The object you apply this shader too won't show up in your render.

11 November 2005, 03:30 PM
It renders faster because there are less samples with global 0 2.
More samples = more rendering.

Did you take a look at the samples diagnostics to check your settings?

The balls with the 2 2 settings should have shown opaque white with their high density of samples. 2 2 means 16 samples per pixel density.

When you say they look 'better' with overrides off, what does that mean?

After this is understood, then put your objects in Francesca's geoshader and set the geoshader samples to 0 2, and the details should get higher samples. And, the
rendering time will go back down.

All of this assumes that you have set contrast low enough to give reasonable sampling range througout your image. Again, use samples diagnostics to check your setting.

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11 November 2005, 03:30 PM
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