"Vincent L." <nomail@nomail> wrote:
> Hi all,
>
> In an attempt to get a clean render, I am trying to tune
> the radiosity settings for the scene.
>
> With the following settings I get round splotches as shown
> on the attached image. I tried various changes in the settings
> making the splotches smaller, or changing their location,
> but to date, I still have round splotches. (I manage to find these
> by comparing with other settings renders ; with nearest_count 10
> splotches move and are less visible, yet there are still splotches).
>
> Has anyone of you encountered such splotches and managed to
> get rid of them ? Any suggestion ?
>
> Here are the settings :
>
> global_settings {
>   charset utf8
>   adc_bailout 0.001
>   max_trace_level 10
>   #if(Rad)
>     radiosity{
>       pretrace_start 0.04
>       pretrace_end   0.02
>       count 300
>       nearest_count 5
>       error_bound 0.07
>       recursion_limit 1
>       low_error_factor .5
>       minimum_reuse 0.01
>       brightness 1
>       adc_bailout 0.01
>     }
>   #end
> }
>
> Vincent
>
> P.S. Splotches are apparently linked to reflection finish
> (finish { reflection { 0.0, 0.5 } }) of the dragons. The same
> scene with matte dragons has no splotches...


The splotches are sampling errors and can be fixed.
Offhand, why is your nearest_count so low? And your pretrace_end could be
smaller, which can allow you to reduce artifacts with such a small error_bound
(without boosting the count).

I am not sure of what you prefer, appearance-wise, but I would change your
radiosity block to:

radiosity{
    pretrace_start 0.080
    pretrace_end   0.005
    count 200
    nearest_count 20
    error_bound 0.07
    recursion_limit 3
    low_error_factor .5
    minimum_reuse 0.01
    brightness 1
    adc_bailout 0.01
}


This is just a guess, though, as radiosity needs to be tuned to fit the user's
quality/speed preferences.

  If possible, can you read through and try what is recommended in the radiosity
tuning guide in the wiki?  The techniques in it have worked well for me and I am
always looking to improve the article.  I still quite a few radiosity questions
on the newsgroups that I thought may have been covered by it, but no one
mentions it, so I don't know if people read it and it didn't work for them, or
if people are just not aware of it.

Another thought is that if it is only associated with reflection, you could use
load_file and save_file to sidestep this.



    -Reactor

Post a reply to this message