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fahr
02-07-2009, 02:31 PM
I'm testing a particle emitter with hypervoxel sprites attached. The sprites look great, but I can't get them to motion blur at all. I'm using photoreal motion blur. Is there a way to get hypervoxels to render with photoreal motion blur? I turned on "particle blur" but that did nothing.
I'm stumped. Any ideas?
Thanks!

Sekhar
02-07-2009, 04:24 PM
Did you set enough number of blur passes? Is your blur length long enough? If both these are good, what version are you using? 9.2 had some limitations - see discussion (http://www.newtek.com/forums/showthread.php?t=58903&highlight=blur).

cagey5
02-07-2009, 04:36 PM
My understanding is that you will only get the blur based on camera movement, not voxel movement. It's a limitation of the current particle system.

Sekhar
02-07-2009, 06:19 PM
My understanding is that you will only get the blur based on camera movement, not voxel movement. It's a limitation of the current particle system.

Yes, that was the case in 9.2 (see link to discussion on that in my post above), but didn't they fix it?

[EDIT]
Did some tests with sprite/surface and thought I'd share. Dither and PR both look fine for sprite (because I guess it's fuzzy to begin with); only dither looks OK for surface. 64 bit 9.6 on Vista.

fahr
02-07-2009, 09:54 PM
I saved a test file to this link:

http://idisk.mac.com/cgleason-Public?view=web

As far as I can tell, this particle/hypervoxel system should be motion blurring, but it's not. Could someone check my settings and perhaps you'll find out why this won't motion blur.

This file was created using 9.6 trial on an intel mac.

Thanks!

Sekhar
02-07-2009, 11:25 PM
I saved a test file to this link:

http://idisk.mac.com/cgleason-Public?view=web

As far as I can tell, this particle/hypervoxel system should be motion blurring, but it's not. Could someone check my settings and perhaps you'll find out why this won't motion blur.

This file was created using 9.6 trial on an intel mac.

Thanks!

Couple of problems. First, like I suspected your blur passes were just 1. LW needs more than 1 to construct the blur, I made it 16. I also changed the type to Dither (for better results).

Next, your scene file appears to be either restricted (because it's a trial?) or damaged in some way. I've copied your scene into a fresh scene, maintaining your settings (except for blur passes and render type).

Below is the render and the modified scene. Check out the scene on your LW and see if you get the same result. If it works, please report the problem to NewTek, pointing to this thread so they can fix the trial version (if that's breaking the scene).

fahr
02-08-2009, 12:20 AM
Thanks for looking into this. Your scene rendered with blur on my machine. I've been doing a ton of additional testing and I'm able to get motion blur on hypervoxels now.
I am, however, a tad confused at the settings needed for blurring hypervoxels. They seem to have a completely different set of rules for rendering than normal geometry.
I can get nice smoothly sampled blur from geometry through photoreal blur just by using antialiasing alone (no blur passes).
Hypervoxels, however, seem to behave exactly the opposite. I can crank antialiasing as high as I want and it will do nothing as far adding motion blur. Only blur samples work and the end result gives you the typical "ghosting" effect that comes from old multi-pass blur techniques. A 16-pass dithered blur looks good, I suspect, because it's... well... 16 freaking passes. :) The end result took nearly 9 minutes for a few untextured balls on screen. :P
In an attempt cut down render times I kept digging. I turned off volumetric antialiasing, thinking that if antialiasing doesn't seem to matter on a muti-pass blur, then who needs it? Wrong. Turning off volumetric antialiasing seems to make it impossible to blur the particles, no matter what your settings are. So that's out.
In the end, the best setting I could come up with was to reduce antialiasing to 1 instead of 4. It cut my render time down to 2 minutes and still looked decent. If I render with sprites, I shouldn't need to worry at all about edge antialiasing anyway...?
The big drawback here is that I am now almost forced to render hypervoxels in a separate scene from my main geometry using completely different motion blur settings, so compositing results may suffer a bit and I will likely have a hard time with integrating things like relections and shadows.
But compromised motion blur is better than no motion blur at all! :)
I hope this is not an issue in Core. Crappy particle rendering is one of the reasons I was getting away from rendering in maya. :P
Thanks again!

Sekhar
02-08-2009, 01:03 AM
You rarely need to increase antialiasing above 1, certainly not when you're blurring things; level 4 is overkill. In fact, I can't remember the last time I used a level above 1.

Next, there should be no difference in blurring regular objects and HVs. See below a render and the scene that has a regular object (top) and a HV (bottom), both moving right. As you can see, both blur fine with the same settings.

There may be an issue with the LW version you have (either being Mac or being a trial), because we still have no explanation for your first scene not getting a blur. Note that if you take your original scene and increase the blur passes, you still don't get any blur - there's something weird about the scene.

fahr
02-08-2009, 10:25 AM
I'm pretty sure that I wasn't getting blur because I had volumetric antialiasing turned off in that scene. But I'll check again.
Thanks for all of the insight on motion blur. I'm new to Lightwave's new renderer and all of it's antialiasing settings are confusing.
If I set my antialiasing to 1, I'm going to get really bad aliasing on geometry edges, won't I? Especially for objects in the scene that aren't moving? Or does adding motion blur passes add antialiasing to those objects, even though they are not blurring.
Cinema 4D uses multi-pass rendering to add antialiasing to a scene as well. If you've got a ton of passes, you don't need to set your antialiasing very high. Is this how Lightwave works as well?

Sekhar
02-08-2009, 11:50 AM
Yeah, the antialiasing settings can be tricky. For most situations though, just leave the Antialiasing level at 1 and select Adaptive Sampling (probably the single most important selection, at least for me!). Then play with the Threshold level. In most cases, the default 0.1 is fine, though sometimes you might have to lower it to 0.01 (dramatically increasing render time).

Selecting Motion Blur and setting Motion Blur Passes is another way. This is like the old way LW used to do it with Classic Camera. In my experience this method is slower than the Adaptive Sampling method above to get equivalent results, so I rarely use it for antialiasing.

Do a search on these forums, you'll find some advanced/comprehensive guidelines.

toby
02-08-2009, 05:43 PM
Yeah, the antialiasing settings can be tricky. For most situations though, just leave the Antialiasing level at 1 and select Adaptive Sampling (probably the single most important selection, at least for me!). Then play with the Threshold level. In most cases, the default 0.1 is fine, though sometimes you might have to lower it to 0.01 (dramatically increasing render time).
This is what I used to think, but Adaptive sampling is totally inefficient below .02. Double rendertimes with no quality improvement. Also, setting a higher number of passes will require fewer adaptive passes because it's higher quality, so it can look better in the same amount of time, and/or reach a level of quality that's impossible with 1 pass.

As far as the particles and HV, keep in mind that particles need Particle Blur to be checked on, and HV is not geometry, it's a post-process, so even though Newtek's done a great job getting hv to interact with everything else in scenes, like casting shadows, the motion blur needs may very well be different.

But, Sekhar, do you not get stepped motion blur on hv surface? I get that just like farh does, but only with hv (I'm on Mac too). If this is a Mac discrepancy we'd want to know about it. For example, with 1 pass aa and 3 pass motion blur do you get a lot of noise, or do you get 3 solid steps -

Sekhar
02-08-2009, 07:50 PM
Also, setting a higher number of passes will require fewer adaptive passes because it's higher quality, so it can look better in the same amount of time, and/or reach a level of quality that's impossible with 1 pass.

I have to check that combination. If I come up with anything interesting, may be I'll post the results here so we can all compare notes. If you have any numbers, please post.


But, Sekhar, do you not get stepped motion blur on hv surface? I get that just like farh does, but only with hv (I'm on Mac too). If this is a Mac discrepancy we'd want to know about it. For example, with 1 pass aa and 3 pass motion blur do you get a lot of noise, or do you get 3 solid steps -
I see steps. But with Classic and Dither, we get the same steps with regular objects as well, so seems to me the behavior is identical between HV and objects for these two MBs. For Photoreal however, I get steps with HV, but a smooth (but noisy) blur with objects when the steps are few. So, Photoreal is working like Classic basically, when it comes to HVs.

But the weird thing I found is that in the scene above that Fahr built with his LW Mac trial, I didn't get any blur with any of the MB types regardless of how many steps I set. This is very weird. Do you mind checking and confirming? Fahr got the blur when he used the scene I created in my LW (64 bit 9.6 on Vista). So, it's something in the way the scene is created, may be. In any case, NT needs to fix it, if true.

toby
02-09-2009, 01:19 AM
I have to check that combination. If I come up with anything interesting, may be I'll post the results here so we can all compare notes. If you have any numbers, please post.
we were talking about it here:
http://www.newtek.com/forums/showthread.php?t=91690&page=3
page 3 on.


I see steps. But with Classic and Dither, we get the same steps with regular objects as well, so seems to me the behavior is identical between HV and objects for these two MBs. For Photoreal however, I get steps with HV, but a smooth (but noisy) blur with objects when the steps are few. So, Photoreal is working like Classic basically, when it comes to HVs.
Same thing here.


But the weird thing I found is that in the scene above that Fahr built with his LW Mac trial, I didn't get any blur with any of the MB types regardless of how many steps I set. This is very weird. Do you mind checking and confirming? Fahr got the blur when he used the scene I created in my LW (64 bit 9.6 on Vista). So, it's something in the way the scene is created, may be. In any case, NT needs to fix it, if true.
Loaded the scene from post #5, as soon as I turned the moblur passes above 1 it blurred fine -