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I'm getting some lighting artifacts when using radiosity. There is one
light in the scene, an area light, in a light group with some spheres. On
the blue sphere (Neptune, actully) I'm seeing some bright patches (upper
left picture). If I change the color of the area light, it doesn't affect
the artifact (upper right). The artifact isn't present in the pretrace
step (lower left). Also, the artifact changes shape/size if I render a
different portion of the image or change the final render size keeping all
other things constant (lower right, also showing a pretrace step).
Any ideas? Thanks in advance!
Here is the radiosity code:
global_settings {
radiosity {
#if (image_width>1500)
pretrace_start 0.01 // start pretrace at this size
pretrace_end 0.001
#else
pretrace_start 0.08
pretrace_end 0.02
#end // end pretrace at this size
count 60 // higher -> higher quality (1..1600) [35]
nearest_count 8 // higher -> higher quality (1..10) [5]
error_bound 1.8 // higher -> smoother, less accurate [1.8]
recursion_limit 3 // how much interreflections are
calculated (1..5+) [3]
low_error_factor .5 // reduce error_bound during last pretrace
step
gray_threshold 0.0 // increase for weakening colors (0..1)
[0]
minimum_reuse 0.015 // reuse of old radiosity samples [0.015]
brightness 0.3 // brightness of radiosity effects (0..1)
[1]
adc_bailout 0.01/2
//normal on // take surface normals into account [off]
//media on // take media into account [off]
//save_file "file_name" // save radiosity data
//load_file "file_name" // load saved radiosity data
//always_sample off // turn sampling in final trace off [on]
//max_sample 1.0 // maximum brightness of samples
}
assumed_gamma 1.0
}
Here is the light group:
light_group {
#if (arealight)
light_source {
0*x
color rgb <255,255,230>/255
area_light
<0.5*Rsun, 0, 0> <0, 0, 0.5*Rsun>
10, 10
adaptive 2
circular
orient
//jitter
translate 1*<8*Rj,1.1*Rsun,-Rsun>
}
#else
light_source {
<0, 0, 0> // light's position (translated below)
color rgb <1, 1, 1> // light's color
translate <-30, 30, 30>
}
#end
#if (radiosity_on)
plane {
y, 0
texture { pigment { color rgb 1.8 } finish { ambient 0.00 diffuse 0.4
specular 0 reflection 0}}
}
#else
plane {
y, 0
texture { pigment { color rgb 1 } finish { ambient 0.10 diffuse 0.6
specular 0 reflection 0}}
}
#end
object { earth translate -Rn*x translate <-2*Re,Re,2*Rj> }
object { moon translate -Rn*x translate <-2.3*Re,Re_moon,2*Rj+Re>}
object { venus translate -Rn*x translate <-4.5*Re,Rv,2*Rj>}
object { mars translate -Rn*x translate <-6.5*Re,Rmars,2*Rj>}
object { mercury translate -Rn*x translate <-8*Re,Rmerc,2*Rj>}
object { pluto translate -Rn*x translate <-9*Re,Rp,2*Rj>}
object { jupiter rotate 180*y translate <1.90*Rs,Rj2, -Rj>}
object { saturn rotate -13*x rotate -65*y translate <-1.7*Rs,Rs2, -Rj>}
object { uranus translate -Rn*x translate <1.5*Rs,Ru2, 2*Rj>}
object { neptune translate -Rn*x translate <0.5*Rs,Rn2, 2*Rj>}
}
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Mike Sobers wrote:
> I'm getting some lighting artifacts when using radiosity. There is one
> light in the scene, an area light, in a light group with some spheres. On
> the blue sphere (Neptune, actully) I'm seeing some bright patches (upper
> left picture). If I change the color of the area light, it doesn't affect
> the artifact (upper right). The artifact isn't present in the pretrace
> step (lower left). Also, the artifact changes shape/size if I render a
> different portion of the image or change the final render size keeping all
> other things constant (lower right, also showing a pretrace step).
>
> Any ideas? Thanks in advance!
> count 60 // higher -> higher quality (1..1600) [35]
Increase this. For low end (test) renders, I use 100. For higher end
(ie final), I use at least 300 (of course, that's just me).
...Chambers
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Ben Chambers <ben### [at] pacificwebguy com> wrote:
> Mike Sobers wrote:
> > Any ideas? Thanks in advance!
>
> > count 60 // higher -> higher quality (1..1600) [35]
>
> Increase this. For low end (test) renders, I use 100. For higher end
> (ie final), I use at least 300 (of course, that's just me).
>
> ...Chambers
Thanks for the tip! I bumped count up to 1000, and it only changed the
shape/size of the artifacts. However, you got me thinking, and by dropping
error_bound from 1.8 to about 0.2 the problem is resolved. Funny thing
though, it seems to be dependent on the pretrace_end size and overall image
size. Anyone have any suggestions as to what causes this in the first
place?
-Mike
PS - planets are to scale, Earth is the largest of the small ones
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