I don't think the problem was due to the background{} ...
If you turn off the normals in radiosity, you will get a similar (or
the same) result ...
the "ambient-normals" of the sphere just scramble the reflections, so
you can't recognize them ...


--
background{rgb 1}camera{location<1,5,-2>look_at 0}#macro
m(a,b,i)#local d=(b-a)
/8;#local
e=vcross(d,y);#if(i)m(a-e,a+e+2*d,i-1)m(a+e,a+2*d-e,i-1)m(a+3*d-e,a+e
+3*d,i-1)m(a+3*d-e,a+5*d-e,i-1)m(a+6*d-e,a+e+6*d,i-1)m(a+8*d-e,a+e+8*d
,i-1)#else
cylinder{a,b,vlength(d)/3 pigment{rgb 0}}#end#end m(-4*x,2*x,4) // Jan
Walzer


"Kari Kivisalo" <kar### [at] kivisalonet> schrieb im Newsbeitrag
news:3AB88380.89C707E7@kivisalo.net...
> Ken wrote:
> >
> > No, I don't. I have never seen any situation in real life that
this
> > would represent.
>
> How can you compare then?
>
> I have seen several photometric images of physical setups and
> corresponding rad simulations in IEEE and other publications
> which clearly show the validity of radiosity. There are differences
> in implementations, like noise in the ray based radiosity, but the
> basic concept is solid.
>
> The problem with all radiosity implementations is that there are too
> many cryptic parameters to tweak so users in general use non optimal
> setup which ruins the simulation. There is an EU project ARCADE
which
> tries to automate the parameter tweak phase among other things so
that
> you don't have to be "Certified Radiosity Technician" to produce
good
> results. http://www-imagis.imag.fr/ARCADE/
>
> This particular scene is a poor choice for meaasuring how realistic
> the simulation is for two reasons. The "sky" emits the same amount
of
> "energy" as the "sun". Nobody has ever seen this situation so it's a
> bit difficult to compare. The scene is also uniform in all
directions.
>
>
> There is something funny going on with background{} and radiosity.
> I rendered the same scene enclosed in a sphere and the anomaly at
> the bottom of the sphere disappeared.
> http://hammer.prohosting.com/~kkivisal/sphere.jpg
>
>
>
______________________________________________________________________
> Kari Kivisalo
http://www.kivisalo.net

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