I just tried to render this (old?) example scene in the newest 3.7 RC7:

	http://www.oyonale.com/modeles.php?page=40

However, I get a completely black image.

It works fine if I turn radiosity off. I notice that when you turn 
radiosity on, the scene has no light sources... but it renders fine in 
POV-Ray 3.6.

Is this a bug in 3.7?

Timwi

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Am 12.03.2013 15:36, schrieb Timwi:
>
> I just tried to render this (old?) example scene in the newest 3.7 RC7:
>
>      http://www.oyonale.com/modeles.php?page=40
>
> However, I get a completely black image.
>
> It works fine if I turn radiosity off. I notice that when you turn
> radiosity on, the scene has no light sources... but it renders fine in
> POV-Ray 3.6.
>
> Is this a bug in 3.7?

No, it's actually a feature. (And I'm not kidding.)

3.7 introduces a major change to the "ambient" mechanism, with the goal 
of making it easier to use one and the same material definition for both 
non-radiosity and radiosity renders.

The "ambient" term is now reserved for modeling ambient light reflected 
diffusely by the respective material - which is exactly what radiosity 
does (albeit at a much more sophisticated level), so the "ambient" 
mechanism is disabled when radiosity is enabled.

For modeling materials that emit light by themselves, a new "emission" 
term has been added to the finish block instead. This is enabled in both 
non-radiosity and radiosity renders, and is also independent of the 
global ambient_light setting.


Of course we're aware that using the "ambient" mechanism for what is now 
catered to by the "emission" mechanism has been ubiquitous, and that 
this change would break plenty of existing scenes, if it wasn't for a 
backdoor we're providing: If "#version 3.6" (or anything lower than 3.7) 
is specified, the "ambient" mechanism remains enabled in radiosity 
renders as well.

Obviously this backdoor only works if the scene in question has a 
corresponding "#version" statement. Unfortunately Gilles' scene does not.


So you have two options for fixing the scene:

(a) Place a "#version 3.6;" statement at the beginning of the .pov file; 
this is what I'd recommend if you just want to render the scene and 
maybe toy around with it a little.

(b) Replace all occurrences of "ambient" with "emission" (and, if 
applicable, multiply the respective parameter by whatever value is 
specified as "ambient_light"); this is what I'd recommend if you intend 
to use the scene as a basis for some work of your own, to be sure all 
the bells & whistles of 3.7 work as they should. (The "ambient" 
behaviour is not the only thing that depends on the #version setting, 
although most of the other stuff is more subtle.)

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On 12/03/2013 16:34, clipka wrote:
> Am 12.03.2013 15:36, schrieb Timwi:
>>
>> I just tried to render this (old?) example scene in the newest 3.7 RC7:
>>
>>      http://www.oyonale.com/modeles.php?page=40
>>
>> However, I get a completely black image.
>>
>> Is this a bug in 3.7?
>
> No, it's actually a feature. (And I'm not kidding.)
> [...]

Wow, thanks for the detailed explanation!

Timwi

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