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Le 2022-06-06 à 03:46, And a écrit :
> "HackerDaGreat57" <Hac### [at] gmailcom> wrote:
>> "Bald Eagle" <cre### [at] netscapenet> wrote:
>>> "HackerDaGreat57" <Hac### [at] gmailcom> wrote:
>>>
>>>> Is it possible to change the 'Radius' of the point light? Like in Blender's
>>>> Cycles for example, there is an option to change the point light's radius which
>>>> increases the 'amount' of penumbra on my shadows.
>>>>
>>>> Thanks anyway for the useful reference though.
>>>
>>> Not in the way you're asking.
>>> But maybe another way.
>>>
>>> If you create a sphere with an emissive finish, then you could make a scene
>>> using radiosity, and that might work in the way you want it to.
>>>
>>> You can also add no_image to the object definition so that it doesn't show up in
>>> the scene, if it's in the camera's view frustum.
>>
>> That would, in fact, work like a charm.
>>
>> Do emissive materials count as light sources? (I'm concerned about the 127 light
>> limit)
>
> You can use an object with texture{ finish{emission 1.0}} instead of regular
> light_source, when the radiosity turn on.
> But, you need very high radiosity quality settings, especially "error_bound", or
> you will get a very blurred shadow without accuracy created by radiosity.
>
> The accuracy will establish when error_bound is very small. But at this time you
> need high "count" to eliminate spotted result.
>
>
>
> radiosity{
> pretrace_start 64/image_width
> pretrace_end 4/image_width
>
> count 160
> nearest_count 2
> error_bound 0.28 // this should be smaller
> // if you use radiosity emission
> // as a light source
> recursion_limit 4
> low_error_factor 0.5
> gray_threshold 0.0
> brightness 1.0 // brightness 1 is natural correct
> media off
>
> }
>
>
> radiosity {} block place in the global_settings{}
>
In a case like that, it's very interesting to use the importance feature
of the latest versions.
It's used as follow :
You start by assigning a default importance weight to everything with a
#default statement :
#declare HighSamples = 50000;
#declare AverageSamples = 75;
#default{rediosity{ importance AverageSamples /HighSamples }}
Then, for the objects to be used as light sources, you add :
radiosity{ importance 1 }
usually just before the closing brace or just before the texture definition.
In cases like this, I tend to also use the adaptive nearest_count :
nearest_count 20 3
#declare HighSamples = 50000;
#declare AverageSamples = 75;
#default{radiosity{ importance AverageSamples/HighSamples }}
global_settings{ assumed_gamma 1
radiosity{
pretrace_start 64/image_width
pretrace_end 4/image_width
minimum_reuse 4/image_width-0.05
count HighSamples
nearest_count 20 2
error_bound 0.2 // this should be smaller
// if you use radiosity emission
// as a light source
recursion_limit 4
low_error_factor 0.35
media off
}
<other optional global_settings stuff>}
That cause the average number of samples used to be about 75 for most f
the scene, but to be up to 50000 when sampling the area near the high
emission objects.
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Op 6-6-2022 om 16:50 schreef Alain Martel:
>
> In a case like that, it's very interesting to use the importance feature
> of the latest versions.
>
> It's used as follow :
> You start by assigning a default importance weight to everything with a
> #default statement :
> #declare HighSamples = 50000;
> #declare AverageSamples = 75;
> #default{rediosity{ importance AverageSamples /HighSamples }}
>
> Then, for the objects to be used as light sources, you add :
> radiosity{ importance 1 }
> usually just before the closing brace or just before the texture
> definition.
>
> In cases like this, I tend to also use the adaptive nearest_count :
> nearest_count 20 3
>
> #declare HighSamples = 50000;
> #declare AverageSamples = 75;
> #default{radiosity{ importance AverageSamples/HighSamples }}
>
> global_settings{ assumed_gamma 1
> radiosity{
> pretrace_start 64/image_width
> pretrace_end 4/image_width
> minimum_reuse 4/image_width-0.05
>
> count HighSamples
> nearest_count 20 2
> error_bound 0.2 // this should be smaller
> // if you use radiosity emission
> // as a light source
> recursion_limit 4
> low_error_factor 0.35
> media off
>
> }
> <other optional global_settings stuff>}
>
> That cause the average number of samples used to be about 75 for most f
> the scene, but to be up to 50000 when sampling the area near the high
> emission objects.
This is very good advise! Note that you may have to crank-up your
emission value way beyond 1. For a rapid test, I used emission 1000
together with diffuse 1, for instance.
--
Thomas
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