View Full Version : The AreaLight/G2/FPrime/F9-quiz

01-05-2007, 03:53 AM

I recently set up a scene using FPrime, but when I hit F9, it looked nothing like what I'd set up. Basically, this was a problem created by the way FPrime displays G2's sss when using an Area Light that has a certain angle on the object. See attachment.

When using other types of lights, FPrime and F9 seems to match up more closely. This only seems to relate to G2's SSS. I've tried searching around the net, but couldn't find anyone talking about this.

In short, when using G2 for sss with an Area Light, FPrime has a better way of rendering than F9.


01-05-2007, 05:07 AM
This is a known issue.

Basicly, Lw cant render G2's SSS with area lights. It's not just subtly different to the F-prime version, it's totally wrong.

I mailed Worley ages ago and they said they know about it, but I don't think there's a way around it. The best thing is just to render with F-prime.

01-05-2007, 06:41 AM
If I remember my G2 manual correctly, unlike the other light types, Worley Labs wrote their own area light code that is automatically substituted for LW's when rendering with F-Prime. If memory serves this was done for speed, cleaness and other technical difficulties associated with LW's area lights. I guess this is one of those technical difficulties.

01-05-2007, 07:44 AM
"[..] Worley Labs wrote their own area light code [..]"

Right, so it's not just me. Well, I'll just have to use FPrime, then, and just comp in SAS and other F9-bound features later on. I don't like it, though, all this fragmented comping stuff is a nightmare when it comes to reflections and shadows...

The other alternative would be using LW's SSS, but that's got such a steep learning curve that I always come back to G2...

Anyways, thanks for prompt responses!


01-05-2007, 01:14 PM
Well, I'll just have to use FPrime, then, and just comp in SAS

I've had to do this on 3 commercials.. It's a big pain in the *****
The Sas alpha's for some reason dont match flush with the Fprime render.
I ended up faffing about in After effects getting it to look ok..
I also E-mailed Worley about this in the hope that the rumoured SAS-2 might work in Fprime.
I don't know what I was thinking, I was a bit overly optimistic that day. Of course they wouldn't tell me nowt bout that.