I cannot seem to find a clear answer for this in the manual…
I am testing the physical sun and sky.
Does the physical sun automatically cast light from the sky as well? or do I need to use a dome light?
As i understand, the Sky is a MAP.
The Sun is there for an easier control of the SKY MAP parameters, when that is left in automatic mode (ie. no “sun” node picked).
It only emits PARALLEL, direct light rays, as far as i gather, just as any max direct light.
In fact max Direct Lights can be picked as “sun node” in the sky map. then and only then teh SKY parameters aren’t dependant from the ones in case attached to the VRay sun, but only dependant from what’s set on the map.
Hope it helps.
Lele
It is based on famous paper from Siggraph. So I think it’s physical 
You can map the sky to a dome light, but I think it works best with a GI solution.
You can always test it out - there’s no light in the shadows of a scene with only a Vraysun. The sky is a map, and doesn’t cast any illumination unless it’s in the environment or gi override environment slots, or as the map in a vray dome light.
There’s a big difference in the amount of light in shadows between using GI and using a dome light.
the sky could be concidered as a procedural hdri
sorry chaps, just to clarify this for myself, do you guys still use the
vray GI environment skylight in conjunction with the vray sun?
Or do you use just the vray sun to illuminate external scenes now?
cheers
steve
all you need to do is add the VRaysky map in your max environment slot
or to your vray environment override slot if you want to have a different background shown
Ah,
Well i am sorry, but i dont think the vray sky produces a "hdri"like sky solution.
While i love these new features esp. together with vraycam, where you get allready much better results, the vraysky does not seem to be a hdri solution.
this i think could get improved still and also would lead to better results.
am i wrong ? the last time i tested this i was sure it only was a colormap. but didnt for example include the stronger light near the sunposition. this leaded to a to strong bluish immage ..
Tom
when i say hdri i mean its a high dynamic range function. plus i believe its the ozone function in the sun and sky that specify how much blue they emit. i forget though which peramiter it was
Hi Da_elf,
are you sure ? I doubt, it´s so.. i am sure in earleier versions the color in rgb of the skymap was calculatet precise,
but didnt have any high dynamic function at all.
chatting to Vlado that time, he told i am right, it wasnt any high dynamic range, but…
its some month now and it could have been changed.
maybe Vlado could bring some “light” in this.
Tom
The colors in the sky are not limited in value in any way, so you can consider the sky to be a procedural HDRI map, yes.
Best regards,
Vlado
Well that pretty much sorts that out 
Ah…
that is what i wanted to here from you Vlado…
nice thing.
Tom
I cannot seem to find a clear answer for this in the manual…
Where is the manual? does it ship with the dongle (if it ever arrives :roll: ) because i couldn’t see anything about 1.5 in the v-ray docs support pages.
is it online anywhere?
Thanks
Mark
there’s no light in the shadows of a scene with only a Vraysun
It’s not true, there’s light, but is much more dark than what you can get with your eyes. I think it depend on your exposure, gamma, and maybe a little bit simplified model of the sky light.
There’s a big difference in the amount of light in shadows between using GI and using a dome light.
I don’t think so, if you use a dome you can just have sharpener shadows than with a low IM (and sometimes also with a high IM)
What I am struggling to understand is - how do I brighten the shadows in a scene using a vray sun and sky ? If the vray sky has hdri like abilities - how are they affected ?
I appreciate it is a combination of parameters but when the shadows are brightened with the color mapping or increasing the camera f-stop the scene gets blown out.
Have also used a dome light but render times go bananas.
You could try making your materials slightly brighter. That would cause them to bounce more light into the shadow areas.
Best regards,
Vlado
I find that on the lit side of the building, I am darkening the materials but at the same time I am trying to brighten the same material on the shadowed side.