Op 06/10/2019 om 21:48 schreef Alain Martel:
> Le 2019-10-06 à 07:07, Warren a écrit :
>> Hi/Hello
>>
>> Recently, I've been modifying a scene I created some time ago that 
>> outputs the
>> following image:
>> https://www.ant01.fr/images/imgAnt01/povray/radarKaboom_1280.png
>>
>> which is inspired from this image:
>>
https://www.universetoday.com/wp-content/uploads/2013/03/IMG_3857a_KaBOOM-at-KSC_Ken-Kremer.jpg

>>
>>
>> I tried to get shadows that are brighter like on the source image but 
>> the only
>> trick that works for that purpose was to add a second light source 
>> with the
>> 'shadowless' keyword (inspired a little from three light point sources 
>> technique
>> for 3d scenes, the shadowless light source is on the side of the sene by
>> comparison with the light that casts shadows). I tried with a single 
>> light
>> source with the following for the color: 'color srgb <1, 1, 0.95>*1.2' 
>> but the
>> resulting shadows are too black. Of course all this imply using 
>> radiosity, so
>> the ambient value must be set to 0 (I use the 3.8 version of povray, 
>> so I don't
>> need to set ambient values to 0 with the '#default' keyword. I saw on 
>> the povray
>> radiosity wiki page that recursion_limit can change the indirectly-lit 
>> object
>> but I didn't see any changes by setting this value to 3 or 4

For open air scenes, recursion_limit can/should stay at 1; it is only 
useful to increase it for indoor scenes. Be aware that render time 
increases also somewhat in that case.

>>
>> So my question is how do you get bright shadows with radiosity ? Do 
>> you use
>> several light sources or do you have others techniques ?
>>
>>
>>
> One thing that you can do :
> Have a sky_sphere with the sky as you like it.
> 
> sky_sphere{pigment{Your_Sky_Pigment}}
> 
> Now, add a large sphere around your scene, Give it the same texture as 
> your sky_sphere, but with a high emission finish :
> 
> sphere{0,1 // So that you don't need to scale your pigment
>   pigment{Your_Sky_Pigment}
>   finish{diffuse 0 emission 3}
>   // Don't interact with lights, but make it bright !
>   scale 10000 // make it large
>   hollow // to remove a warning and allow the use of media & fog
>   no_image no_reflection // So that it don't show
> }
> 
> That's not the only option.

indeed, but yours is an easy and fast solution.

Otherwise, in the radiosity block, if you have not done so, switch 
'normal' and/or 'media' to 'on' (off by default).

-- 
Thomas

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