View Full Version : renders, exponintionaly slower w/ photoreal blur

05-15-2007, 01:59 PM
So, I had this issue in beta where when I had photo real motion blur, I would do test renders and each frame was around 10 min, then I would let it go all night to render a sequence on one machine and it should have been done by morning, but when I came back it was taking several hours per frame. I narrowed it down to the photo real motion blur. when I changed it to classic and then cranked up the motion blur passes it finished fine in a reasonable time. So anyway now I have a shot that has depth of field and motion blur and Radiosity, Final gather, and each test fram is like 10 min but when I went to render it over night by morning it was still going and was several hours a frame? the render times are fine because of the adaptive sampling, if I have to use the old brut force AA passes the render times will be way to long,

any ideas?


05-15-2007, 02:08 PM
I should probably clarify that each frame seems to take longer. for example the first ones take x amount of time and when i get back the next day each frame is x times 10. and the scenes is such that actually the first frames should take longer than the last ones, and in my render tests do?

05-16-2007, 12:28 PM
what are your setting for the motion blur?

05-17-2007, 12:37 PM
settings are actually, photo real, passes 1, blur 100% AS .02

it looks great in the frame tests, it's just the scene render that just gets to long.

I added hypervoxels to the scene and found out that for hypervoxels you have to uses passes to get it to do the motion blur, which resamples the radiosity which makes render times go way to high, so i'm now rendering in fprime :) only one machine, but what do you do. So I can finish the shot, just a mater of figuring out if this is a bug or what's going on? When I get some time I'll try to recreate a scene that has this issues...

thanks for the help

05-17-2007, 04:02 PM
Deformations will really kill Photoblur, you have to use multiple blur passes to get the times back down.

05-17-2007, 10:05 PM
hmm, the only think i can think of is to make sure your blur pass is only set to 1 and set AA passes to 1 also. Let AS do the rest.

When it comes to hypervoxels it seems to only use the old classic method of blur so you have to increase the blur passes to get it, but that really adds a lot of time to your render since it also multiply your AA and AS passes.

05-21-2007, 02:11 PM
Photoreal blur is great for stills, but really isnt practical for lengthy animations IMO. I normally render my vectors out and smooth the MB pass stepping with reelsmart motion blur.

Elmar Moelzer
05-23-2007, 11:06 AM
You can always add more steps in the PRMblur.
That will help a bit with rendertimes.
I am not sure though why your rendertimes are getting higher with each frame (from what I understand you meant).
Could it be a memory issue?

05-23-2007, 04:22 PM
I've heard this problem before, can't remember who else posted it anymore though, seems to be a bug.

05-29-2007, 08:03 AM
same here...first I did some test renders without Photoreal motionblur

frame 1 = 12mins
frame 60 = 4 mins

after I turn PRmotionblur on, press F10 and go home expecting the 100 frames to be rendered at 1 am, I arrive here today at 3pm and is on frame 60!?

I open windows explorer to check at what time the frames were saved and every frame it adds some time...frame 1 = 5mins, frame 30=10mins, frame 40=26mins, frame 50=52mins, frame 57 = 1h5mins!!!

05-29-2007, 11:03 AM
So, it is a problem within LW i assume, have any of you tried rendering the scene with LWSN or another dispatcher service thatallows you to resubmit the scene to LWSN and doing just one frame render (so it reloads LWSN and the scene for every frame that has to be rendered in the sequence)