Sunlight and size of the sun

[tobias_link]

Hi all, the sunlight system provides the parameter for the Sun size - is there a "sort of" physically correct value? I guess more or less a correct span of values? I'm trying to figure out with which Sun size the sharpness of shadows will be physically correct... Any hints? advice?
thanks very much!
Oliver

[manishpaul_simon]

Hi Tobias
I generally change the size multiplier value to "10"
It works well as it makes the shadows soft and doesn't blur them out too much.

Anything between 5 to 10 works well. And for sharp shadows, keep it to around 2.

[konstantin_chaos]

Hi guys,

The default sun size (Size Multiplier of 1) is the physically accurate one according to the V-Ray's sun and sky system.
The scientific studies and papers that our system is built upon are referenced at the bottom of the docs page - https://docs.chaos.com/display/VSKETCHUP/SunLight

You have to keep in mind that in reality the Sun disk can appear different in size depending on the atmospheric conditions (clouds, fog, etc.) as well as depending on the measurement device or camera.
That's why it's mostly up to you to find a good Size Multiplier for your project (there is a creative aspect to this).
This multiplier controls shadow softness/blurriness too which affects the appearance of your renders quite a bit.
I'd recommend you look at some reference photos you like and then try to match the result in V-Ray.

Hope that helps,
Konstantin

[tobias_link]

Hi Konstantin, thanks very much, this helps! When I compared real photos with a rendering I made, I found that between 0.8 and 1 delivers the same result, so I guess I leave the sun size at default of 1.
Thanks, Oliver!