On 2013-12-15 01:56, clipka wrote:
>
> The answer is quite simple: As various internal "fudge factors" are set
> to 1e-6, scene details should be a good deal larger than that.
>

Well, I can live with the fact that s=1e-6 doesn't render anything, 
although I think that POV-Ray should be free of internal absolute fudge 
factors that break scale invariance. If these are really needed, they 
should be relative so they work at any scale, or at least modifiable by 
the user.

The problem is that even quite large scales s>>1e-6 result in different 
images. The stripped-down scene I posted earlier might somewhat conceal 
the severity of my problem. The following closer to what I actually try 
to render: Transparent thin surfaces. Notice the vast difference in 
visual appearance depending on s=1 or s=10. Interestingly, the 
difference vanishes for thicker surfaces (e.g. 1/100 instead of 1/1000).

I'm stumped. Please tell me how I can scale such thin transparent 
surfaces to get an equivalent visual.


// START SCENE FILE

#version 3.7;

#declare s = 10; // try 1 or 10

camera {
	location 0.1*s*z
	look_at 0
}

sphere {
	0, s
	texture {
		pigment { rgb 1 }
		finish { emission 1 diffuse 0 }
	}
}

#declare shell = difference {
	sphere { 0, 1.001 }
	sphere { 0, 1 }
}

union {
	object { shell translate -x/2 }
	object { shell translate x/2 }
	scale s*0.03
	material {
		texture {
			pigment { rgb 0.9 filter 1 }
			finish {
				ambient 0
				diffuse 0
				reflection { 0, 1 }
				conserve_energy
			}
		}
		interior {
			ior 1.61
			fade_power 1001
			fade_distance 6*s
		}
	}
}

// END SCENE FILE

Post a reply to this message

Attachments:
Download 'scale_problem2_1.png' (4 KB) Download 'scale_problem2_10.png' (3 KB)

Preview of image 'scale_problem2_1.png'

Preview of image 'scale_problem2_10.png'