Le 2019-11-14 à 15:49, Dick Balaska a écrit :
> On 11/14/19 7:26 AM, William F Pokorny wrote:
>> On 11/14/19 2:27 AM, Dick Balaska wrote:
>>>
>>> Changing my SDL from #version 3.7 to 3.8 causes the image to be much 
>>> darker.
>>>
>>
>> One of the changes 3.7 to 3.8 was to take the default ambient to 0.0. 
>> It's a funky color adder disconnected from gamma handling, and at 0.1, 
>> it tends to brink near blacks way up in intensity with AG 1.0 - 
>> washing out the contrast in the images. Your 1.7 AG is already 
>> compensating for this effect to a large degree.
>>
>> Have you tried changing the default ambient back to 0.1 when changing 
>> your version to 3.8?
>>
>> Bill P.
> 
> I'm trying to explore/understand this.
> This,
> https://www.povray.org/documentation/3.7.0/r3_4.html#r3_4_1
> says the default ambient is <1,1,1>, not 0.1.  Am I looking at the wrong 
> thing?
> 

Yes, you are looking at the wrong thing.

This refers to ambient_light in the global_settings. This is not the 
default ambient value but a multiplicator that is applied to every 
ambient values in the whole scene.

If you set that value to <1,0,0>, then, ALL ambient, default and 
explicit, will become red. Then, if you have an ambient value set to 
something like rgb<0, 0.02, 0.1>, it will result in black.

You need to look in the finish section :
https://www.povray.org/documentation/3.7.0/r3_4.html#r3_4_6_3_1



Alain

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