[Radiance-general] high reflectance & roughness metals

[Ignacio Munárriz]

I was disturbed with the horizontal lines that was present in the metal
http://www.alfanature.com/avis/exteriore3b.jpg

son i took a look at the code normal.c, first discovering that the random
functions
lrand48(), drand48() in random.h
did not work in my computer (return always 0), so i changed them for:
#define random() rand()
#define srandom(s) srand((unsigned)(s))
#define frandom() (random()*(1./2147483648.))
then random works but continued with the artifact, then i changed normal.c
in this way:

instead of multisamp(rv, 2, d);
rv[0]=frandom();
rv[1]=frandom();

i think that multisamp creates a pattern in the random because the randoms
numbers i got were rare( some too exacts .50000 0.00000 .7500000)

and the result is
http://www.alfanature.com/avis/exter.jpg






----- Original Message -----
From: "Gregory J. Ward" <gregoryjward at gmail.com>
To: "Radiance general discussion" <radiance-general at radiance-online.org>
Sent: Friday, February 25, 2005 6:24 PM
Subject: Re: [Radiance-general] high reflectance & roughness metals


Hi Ignacio,

If you prefer standard Monte Carlo sampling over the low-discrepency
method, then you should recompile with -DMC as a flag in your rmake
script.  The only way to reduce the noise is to increase your sampling
density (initial rendering resolution).

-Greg

> From: Ignacio Munárriz <gvn at retena.com>
> Date: February 25, 2005 12:40:40 AM PST
>
> hi, althought i guess it has been discussed already at the forum, i've
> having some problems with high reflectance & roughness metals to
> simulate a
> diffuse   metal (alluminium) garage door
>
> ...

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