blackbody shader?

[RevitGary]

I am trying to do the blackbody shader on my skyportals. It turns the portals black

I am trying to follow the instructions here

http://www.3dallusions.com/forums/mr...light-tip.html

Any one have any ideas what I am doing wrong?

[Dave Buckley]

are you doing the bit where you need to drag the shader over to the mat editor?? in there you can adjust the colour temp and brightness. you may also need to adjust output value of sky portal multiplier too

[RevitGary]

Yes I am.

What are proper settings temperature and intensity?

[Dave Buckley]

What are proper settings temperature and intensity?

There aren't any, it depends on your scene, exposure etc. The temperature purely depends on what colour you want you light to be based on your whitepoint setting, and the intensity depends on your ev value i would imagine

[RevitGary]

I have the temp at 10000 which I believe is outdoor white.
and the intensity at 1000 I dont know why
and the multiplier at 10 once again I dont know why

do these setting sound reasonable ?

[RevitGary]

Well it doesnt really matter I was doing this as a test. I thought it would be quicker than a regular skyportal it seems it takes the same amount of time.

unless I am doing something wrong

[Brian Bradley]

Well it doesnt really matter I was doing this as a test. I thought it would be quicker than a regular skyportal it seems it takes the same amount of time.

unless I am doing something wrong

Hey Gary

Am just curious as to why you would think this would be
'quicker' than just using the portal as is?

The beauty of this technique is that it allows you to very
specifically use Kelvin temperatures for lighting and/or reflection
cards in your scene and have the results be very predictable.

regards
Bri

[RevitGary]

It has been mentioned in another post that this would be quicker

"even adding a blackbody shader to the portals makes them much faster and cleaner"

http://forums.cgarchitect.com/38854-render-times.html

I am just trying to get my renderings as quick as possible.
They seem to take forever on a very good machine

[Brian Bradley]

Hi Gary,

Only checked out the 2 threads you have mentioned very quickly but
i think they are both talking about using shaders (such as the BlackBody)
in very different ways!
Jeff on the 3D Allusions thread was taking the BB shader and using
it to accurately place Kelvin Colour temps in a scene, the CGArchitect
thread is actually using a different shader in the 'Light Shader' slot
to completely take over ALL functionality of the Portal light!

Regards
Bri

[Jennifer]

For degrees in Kelvin 1800 is a candle, 3000 incandescent, 5000 daylight at horizon, 6500 bright outdoor blue sky. 9000-20000 would be the actual sky color. 1000 is smallest value.

Intensity is in candelas per meter square, so the larger your light object the more light that is produced. A 3 meter object creates 9 times the light of a 1m object.

Jenni