Thank you for tips.
One clarification: may I remove AA from the first step as it will not affect 
the values stored in the radiosity file?

I also just realized with more tests that if I use the same radiosity 
parameters at both steps, the second one runs much faster. If I change 
'count', 'error_bound', 'recursion_limit' even to more relaxed values, it 
takes more than double of the time to render.

Rgds,
Zoly

"Alain" <ele### [at] netscapenet> wrote in message 
news:46d86fb9@news.povray.org...
> Zoly nous apporta ses lumieres en ce 2007/08/31 12:49:
>> Hi,
>>
>> I am finishing a set of scenes that make intensive use of radiosity as 
>> the light comes from outside of the space that I am designing. To allow 
>> more light to enter through the windows, I am applying radiosity in 2 
>> steps:
>>
>> 1. Render without windows storing the radiosity info (save_file)
> Windows without the "glass" pane.
>> 2. Render with windows and reading the radiosity info from the file 
>> (load_file).
>>
>> I have some doubts about how storing radiosity info works. I would 
>> appreciate some lighting (in my mind):
>>
>> 1. What radiosity parameters have influence on the info that is stored in 
>> the file (all of them?)
> All of them.
>> 2. What radiosity parameters have influence on the image if I am using 
>> load_file?
> Any can have an effect, when there is a need to gather some extra samples.
>> 3. Does the info in the file overwrite the radiosity parameters in the 
>> SDL code?
> NO.
>> 4. Can I make the first step at a lower size than the second step?
> Absolutely. You can also remove any AA.
>> 5. Does it matter where I put the parameters load_file and save_file in 
>> the code (after the actual radiosity parameters, after them, ...?
> load_file
> radiosity parameters
> save_file
> or
> radiosity parameters
> load_file
> save_file
>
> If you save_file before load_file, you may reload the data you just saved.
>> 6. If I get some artifacts in the first step, may I remove them in the 
>> second one?
> The second step will gather additional samples if needed. They may, or 
> not, remove or reduce those artefacts.
> Use high quality parameters in the first pass, and more relaxed ones on 
> the second pass.
> In the first pass, remove any flat transparent, colorless, objects. 
> Reflective objects should have the texture replaced by a plain white one 
> IF they are far from bright surfaces: high ambient ones.
> Keep shaped with ior or colored transparent objects as they actively 
> change the radiosity samples. Also, keep non-flat reflective
>>
>> Thanks for your help,
>> Zoly
> If you also use photons, you must keep any object that is a target for the 
> photons.
>
> -- 
> Alain
> -------------------------------------------------
> You know you've been raytracing too long when you have ever brought your 
> computer to its knees by mistakenly launching 64 simultaneous frames to be 
> traced, while trying to maximizing the benefits of parallelizing them.
> Carsten Whimster

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