View Full Version : Frame Rendering times get progressively longer

07-15-2011, 12:16 PM
My problem:
When I render a 150 frame scene each frame render time gets progressively longer.

For instance:
frame 30=30 seconds
frame 40=45 seconds
frame 51=103 seconds
I restart the render and
frame 52-58 = about 54 seconds
frame 60 = 60 seconds
frame 70 = 67 seconds
frame 73 = 73 seconds
frame 77 = 86 seconds
frame 82 = 105 seconds
frame 87= 125 seconds
frame 88= 129 seconds

I restart the render and
frame 89= 30 seconds
frame 91= 29 seconds
frame 93 = 30 seconds
frame 94 = 36 seconds
frame 95= 41 seconds

It is not that the onscreen complexity increasing, because as shown above, when I restart the rendering the renders times speed up.

I have tried restarting my Mac, quitting and relaunching lightwave.
My files are all local to my hard drive

Details on the file:
Radiosity=Final gather
antialiasing = 6
RecFilter = Classic
Adative = off
Motion blur = off
Ray tracing on for Shadows, Relections
8 render threads.

Details on setup
Mac Pro 2x3.2 GHz Quad Core Intel Xeon
8 core
26 GB Ram
OS X 10.6.7

Has anyone seen this before? Uncertainties like this drive me nuts.

This is my first major project now that I finally installed Lightwave 10, so perhaps that is where the problem lies. I have been using Lightwave for over 11 years, so I'm not a complete moron, but I always feel a bit insecure using it.

07-15-2011, 12:19 PM
Are you using GI cache? or other caches?
Every frame you have new samples added to cache, and checking them increases render time.

07-15-2011, 12:34 PM

I do have Global Illumination cache on. I've now turned it off and restarted the render I will have to collect a series of frames to determine if that fixes the problem.

I had GI on because without it sometimes the Raydiosity creates a flicker. Do you know a way around that?

07-15-2011, 01:00 PM
Why new GI sample is made? Because there is not enough existing samples meeting tolerance and angle.
New one is made, and put to cache, and it grows and grows, every frame.
To check what is GI average there is needed to scan all samples in range. The more samples, the slower.
I would just leave as is. Or buy new machine(s) and build renderfarm. If it's paid job. Flickering is kinda unacceptable.
Quiting and restarting render will destroy GI cache, so there will be flickering again in place you stopped render.
You can try calculating GI cache at once in Render Globals, and then lock GI cache permanently.

07-15-2011, 01:09 PM
It's the GI cache.. it's annoying as hell.

07-15-2011, 01:16 PM
cheat the GI , spinning light trick

07-15-2011, 03:19 PM
Thanks guys, it looks like Global illumination was the culprit.

I appreciate the fast answer.

4D Artist Ben,
Thanks for the commiseration, it's nice to know the pain I feel is not unique to me nor solely due to my own incompetence. BTW, your demo real is beautiful.

Online Render,
Spinning light trick... that's kicking it oldschool. Well if it ain't broke don't fix it, so I guess I'll reuse that old trick in the future.