hmmm weird daylight system

daveb867 · June 5th, 2008

just been doing testing in max 2009 and mental ray

trying to light an interior but i seem to think that when using sky portals, changing the mrsun intensity has no effect on the scene whatsoever, other than making the sky portals not as blown out, see the attached images

the only difference between the two is that one where the sky portals are really bright has the sun set at 1

the other has sun set at 0.2 with a bit of transparency on portals???

any thoughts

novelh · June 5th, 2008

I thought the sky portal transmitted sky light not sun light. Try increasing the sky intensity.

daveb867 · June 5th, 2008

sorry yes they do, but i also thought they directed the correct amount of photons through the relevant window, in which case photons come from the sun.

but if there is sunlight entering the room through windows, you would assume that decreasing the mulitplier of the sun would have an effect on the whole scene rather than just the intensity of the portals???

or have i got mixed up

Macer · June 5th, 2008

The MR sky shoots it's own photons (seperate from the sun) and just to confuse things moe the manual states:

NOTE

mr Sun and mr Physical Sky can inherit parameters from mr Sky even if the

latter is off.

The sky portals gather sky light only, not sun light. I think I read somwhere that sky portals work best when the sun isn't shining through them?

Also make sure that you delete or don't save the FG map between tests, as this will transfer the lighting info.

I hope this helps...

Brian Bradley · June 5th, 2008

Quote:

Originally Posted by Macer

The MR sky shoots it's own photons (seperate from the sun)

The Portals do indeed shoot photons but the
MR Sky itself doesn't.

Regards
Bri

Justin Hunt · June 5th, 2008

The portals just get the colour from the mrsky, not intensity or anything else.

Think of them as glorified Area lights.

jhv

Macer · June 6th, 2008

Okay, so the MR sky doesn't shoot photons - but is it like an area light? How is it treated by the render engine? Just curious as to how it works. It shows up as a ray traced light at render time.

June 5th, 2008	#2 (permalink)
novelh Member Join Date: Jan 2008 Location: Miami, FL Posts: 42 Name: Novel Hernandez	Re: hmmm weird daylight system I thought the sky portal transmitted sky light not sun light. Try increasing the sky intensity.

June 5th, 2008	#3 (permalink)
daveb867 Veteran Member Join Date: Aug 2006 Location: Manchester Age: 22 Posts: 701 Name: Dave Buckley	Re: hmmm weird daylight system sorry yes they do, but i also thought they directed the correct amount of photons through the relevant window, in which case photons come from the sun. but if there is sunlight entering the room through windows, you would assume that decreasing the mulitplier of the sun would have an effect on the whole scene rather than just the intensity of the portals??? or have i got mixed up

June 5th, 2008	#4 (permalink)
Macer Senior Member Join Date: May 2006 Location: Cumbria, UK Age: 34 Posts: 183 Name: Mark Cronin	Re: hmmm weird daylight system The MR sky shoots it's own photons (seperate from the sun) and just to confuse things moe the manual states: NOTE mr Sun and mr Physical Sky can inherit parameters from mr Sky even if the latter is off. The sky portals gather sky light only, not sun light. I think I read somwhere that sky portals work best when the sun isn't shining through them? Also make sure that you delete or don't save the FG map between tests, as this will transfer the lighting info. I hope this helps...

June 5th, 2008	#6 (permalink)
Justin Hunt Veteran Member Join Date: Jan 2005 Location: Brisbane Age: 33 Posts: 1,361 Name: Justin Hunt	Re: hmmm weird daylight system The portals just get the colour from the mrsky, not intensity or anything else. Think of them as glorified Area lights. jhv

June 6th, 2008	#7 (permalink)
Macer Senior Member Join Date: May 2006 Location: Cumbria, UK Age: 34 Posts: 183 Name: Mark Cronin	Re: hmmm weird daylight system Okay, so the MR sky doesn't shoot photons - but is it like an area light? How is it treated by the render engine? Just curious as to how it works. It shows up as a ray traced light at render time.

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