Queen soft nous apporta ses lumieres en ce 2008/02/09 14:04:
> I have a problem obtaining nice sharp edges.
> I have tried several antialiasing methods and huge resolution renderings
> (something like 8000x6000). I still get jagged edges. Mostly when overlapping
> shapes. If shape is directly over background, the edge is quite nice.
> Please take a look at attached samples.
> I have used INI settings:
> Green spikes image: http://img229.imageshack.us/my.php?image=spiky2zo7.jpg
> Antialias=On
> Sampling_Method=2
> Antialias_Threshold=2
A very high treshold value. Almost every pixels will stay under that difference.
> Antialias_Depth=2
> Test_Abort_Count=400
Over the white background, the difference is large enough to trigger the 
antialias process, but elsewhere, the difference is just not large enough.
You probably want something more like 2/256 (0.0078)or 2/(256*3) (0.0026).
> 
> Green blob: http://img223.imageshack.us/my.php?image=002005gx6.jpg
> Antialias=On
> Sampling_Method=2
> Antialias_Threshold=5
An absurdly large treshold value, NO pixel will exeede that value.
> Antialias_Depth=1
> Test_Abort_Count=500
Here, the treshold is so large that antialias never have a chance to kick in.
You probably want something more like 5/256 (0.0195) or 5/(256*3) (0.0065).

> 
> 
> 
> 
In POV-Ray, the rgb values range from zero to 1. The difference between 2 pixels 
is calculated as the sum of the absolute values of each channels. That 
difference normaly stay in a 0 to 3 range.
In your examples, you probably want a difference of 2 on a scale that goes from 
zero to 256.
The "default" antialias treshold is of 0.3.
Set Antialias_Threshold to something like 0.1 and you will get much beter results.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you've tried to scan your face for 
a texture.
Quietly Watching

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