Le 19-03-15 à 07:54, Thomas de Groot a écrit :
> On 15-3-2019 9:35, Thomas de Groot wrote:
>> On 14-3-2019 13:28, Thomas de Groot wrote:
>>> On 14-3-2019 8:43, Thomas de Groot wrote:
>>>> The small issue I was talking about is the thin line of light 
>>>> visible between the glass/lead and the window frame. It could be the 
>>>> window being a tiny bit too small but I guess it is light "leaking" 
>>>> at angles. Something similar is shown at the angle between floor and 
>>>> wall. I dimly remember this phenomenon was discussed many years ago 
>>>> and I do not remember the way to correct that, except, I believe, by 
>>>> using stochastic anti-aliasing. I shall test that in any case.
>>>>
>>>
>>> As I supposed indeed, stochastic antialiasing (with no_cache) solves 
>>> the issue.
>>>
>>
>> The downside of this is that combining stochastic aa with photons, 
>> will dramatically decrease render speed. A rough calculation for the 
>> image above, with a crude setting of aa (+a0.1) and with photons 
>> enabled, shows that it will take at least 24 hours to render. :-(
>>
> 
> Not precise enough I am afraid. I need to give you more relevant info:
> 
> + The issue mentioned above was solved using UberPOV, without photons, 
> and with no_cache on in the radiosity block. Command line: +w640 +h640 
> +am3 +a0.01 +ac0.995 +r3 +bm2 +bs8 +wt6. Radiosity's count was lowered 
> to 10. Render time seemed acceptably "low" (I didn't render a complete 
> image).
> 
> + The same settings using UberPOV, this time with photons on, the render 
> time soared up to the estimate of 24 hours+.
> 
> + Using the latest version of 3.8, and with identical settings for +am3 
> on the command line (no_cache is /not/ available in this version), both 
> with or without photons available, the render time was "low" i.e. 
> acceptable for a test and within the hour. However, the issue mentioned 
> above was *not* solved. I tried to increase dramatically the count value 
> in the radiosity block but to no avail where the issue was concerned.
> 
> I would like some expert's view on the matter please.
> 

The most obvious issue that I see is where the wall meet the floor. It 
looks like you are getting radiosity samples from the back of the wall.
Some possibility :
Make the wall go slightly lower than the floor.
Place another box inside the wall at the floor's level.
Add a plinth in front of the wall. It can make the scene more realistic 
at the same time.
Scale up the whole scene by some factor, like 10 times. If using spacing 
for the photons, increase it by the same factor.

If you have some problem with the window, try making the outer edge 
broader so that it goes into the red frame.


Alain

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