View Full Version : I have a LW/FPrime bug, please help

Boris Goreta
08-27-2008, 10:51 AM
I have one strong spotlight lighting the top of the flat box. Underneath the box I have some other geometry which gets lit by the spotlight when it should stay totally black since the flat box is blocking all the light from the spotlight. I use FPrime Monte Carlo radiosity with 2 bounces.

Why is this important to me. I have to make a 20 store building at night. I use several spotlights on every store for inner lighting. It bugs me when the light leaks to the lower store which for example should be totally dark. I've made this simple scene to illustrate the problem.

When using interactive renderer the problem is more pronounced, eventaully leaking light gets dimmer and dimmer but it never goes away.

Please help !

LW 9.5 32bit on Vista Ultimate 64bit
FPrime 3.2
Xeon 8 cores at 3.0 GHz

08-27-2008, 10:58 AM
I've only got an older version of FPrime, not the newer one you have. Might be though that Worley has to catch up his code to the newer 9.5 release of LW.

Question though: if your using a 64bit machine with 8 cores and 12 gigs of ram, and with the render speed improvements to 9.5, why not use the native renderer? does this problem appear there as well?

Boris Goreta
08-27-2008, 11:05 AM
Oh, silly me, I've sent 9.5 scene so older LW's can't read it. Here is the 6.0 scene file version.

Can you try it with the FPrime version you have ? Just hit previewer and tell me if you get any light under the top flat box.

9.5 became much better, but for rendering glassy skyscrapers FPrime is still the way to go, much faster and no tweaking required.

08-27-2008, 05:32 PM
Hi have tried on my LW 9.5 and Lw 9.3.1

bug on image renderer on lightwave 9.5 :(

08-27-2008, 06:59 PM
confirmed! native renderer looked fine, fprime renderer looked exactly like yours. what's the solution? dunno. the worley organization is a tough nut to crack.

08-29-2008, 12:15 PM
Fprime is hosed in 9.5. I've pretty much given up on it until worley can catch up when NT give a final 9.x.

09-06-2008, 05:24 AM
not sure if this will help. sometimes i've noticed this behavior with fprime in my scenes, doesn't often crop up. I'm sure i fixed it to some degree by subdividing the large polygon that the light was leeking through. Try that and see if it helps at all. I suppose some theory behind it might be that fprime cuts a lot of corners to get its monte-carlo style render speed, and giving it more physical polygons to consider helps it define better shadow areas, just a guess but worth a try.


09-07-2008, 05:28 AM
I've found more and more than scenes need special attention to work in Fprime now - the previewing has its uses, but they are diminishing. I don't use Fprime for final, and I don't mean to be 'ignorant' or flippant, but the number of times I start Fprime, see the result being way different to F9 and then just quitting Fprime, is happening more and more.

Roll-on Worley sorting it, or better perhaps, NT instigating their own version.