Problems with OpticalFlow slo-mo, wavy watery shapes around people. Help? at DVinfo.net

David Garvin · September 10th, 2008, 04:53 PM

I am running some QT files through Motion 3's "optical flow" for slow motion. It took me a bit to get some things figured out, but it finally seems to be working correctly. The problem is when I have people walking through the frame in front of other objects, it creates this odd artifacting that looks like watery waves or a shimmering force-field around them.

It's really bad and makes the footage unusable. Is there any way around this? I'm slowing things down to 75%, would slowing them down LESS be a better option? I mean, I could slow the clip down to 95%, and then take that exported clip and run it through again at 95% and then again and again, but it already takes so long just to do one clip, I'd really like to find a reasonable solution.

Thanks

Aric Mannion · September 11th, 2008, 01:03 PM

I use After Effects and Final Cut, so I'm not familiar with that particular effect. I think final cut does a fine job adjusting the speed (but AE is supposed to be much better when you know what you are doing). The point is if you just want to slow it down give Final Cut a try, just see if you prefer it with frame blending on or off.

Moayad Hassan · September 13th, 2008, 07:16 PM

That's how optical flow should look like, it may not work for all kinds of scene. Try using Frame Blinding instead.

Dean Sensui · September 14th, 2008, 02:32 PM

I had a similar problem when using "pixel motion" to get a slo-mo effect in After Effects (probably similar to optical flow in FCP). I switched to frame blending and it was much better.

As Moayad mentioned, pixel motion or optical flow might work well for certain types of scenes and not so good for others. Just have to test it and see.

David Garvin · September 14th, 2008, 10:05 PM

Thanks for the replies. I tried all kinds of speeds just in case I could sneak by the problem, but I cant. I'll try a frame blending technique for these instead.
Thanks

September 10th, 2008, 04:53 PM	#1
David Garvin Major Player Join Date: Feb 2007 Location: Central, OH Posts: 207	Problems with OpticalFlow slo-mo, wavy watery shapes around people. Help? I am running some QT files through Motion 3's "optical flow" for slow motion. It took me a bit to get some things figured out, but it finally seems to be working correctly. The problem is when I have people walking through the frame in front of other objects, it creates this odd artifacting that looks like watery waves or a shimmering force-field around them. It's really bad and makes the footage unusable. Is there any way around this? I'm slowing things down to 75%, would slowing them down LESS be a better option? I mean, I could slow the clip down to 95%, and then take that exported clip and run it through again at 95% and then again and again, but it already takes so long just to do one clip, I'd really like to find a reasonable solution. Thanks

September 14th, 2008, 02:32 PM	#4
Dean Sensui Inner Circle Join Date: Oct 2001 Location: Honolulu, HI Posts: 2,054	I had a similar problem when using "pixel motion" to get a slo-mo effect in After Effects (probably similar to optical flow in FCP). I switched to frame blending and it was much better. As Moayad mentioned, pixel motion or optical flow might work well for certain types of scenes and not so good for others. Just have to test it and see. __________________ Dean Sensui Exec Producer, Hawaii Goes Fishing

September 11th, 2008, 01:03 PM	#2
Aric Mannion Major Player Join Date: Apr 2006 Location: Boston, Massachusetts Posts: 616	I use After Effects and Final Cut, so I'm not familiar with that particular effect. I think final cut does a fine job adjusting the speed (but AE is supposed to be much better when you know what you are doing). The point is if you just want to slow it down give Final Cut a try, just see if you prefer it with frame blending on or off.

September 13th, 2008, 07:16 PM	#3
Moayad Hassan New Boot Join Date: Jan 2008 Location: Birmingham, UK Posts: 16	That's how optical flow should look like, it may not work for all kinds of scene. Try using Frame Blinding instead.

September 14th, 2008, 10:05 PM	#5
David Garvin Major Player Join Date: Feb 2007 Location: Central, OH Posts: 207	Thanks for the replies. I tried all kinds of speeds just in case I could sneak by the problem, but I cant. I'll try a frame blending technique for these instead. Thanks