Reverse Motion Keyer? at DVinfo.net

Daniel Raebiger · March 7th, 2010, 11:14 AM

Hey Guys,

I've got a static shot here with two people entering the frame from the left and right, meeting in the middle.

For some reason i'd like to replace the background of the shot with a graveyard. In my search for a way to do this without painfully masking the people by hand I've found the BCC Motion Key plugin which can remove moving objects from a frame. It works really well.

So i am wondering: if bcc motion key can detect what moves and removes it - is there a way to keep whats moving and remove all the background?

Thanks :)

Gregory Gesch · March 7th, 2010, 06:12 PM

Hi Daniel. In Effects/Keying there is the Difference Key which is designed for that - though it has variable results especially if there are shadows. If you are getting a clean key from BCC Motion Key (sorry I have never used it) and it creates masks around the moving figures you might be able to go into the mask properties and iether invert them or set them to 'subtract'?

Gregory Gesch · March 7th, 2010, 06:22 PM

Sorry about the double post but can't figure how to delete this?

Daniel Raebiger · March 7th, 2010, 08:08 PM

that was sort of obvious. now i really feel stupid ;)

thanks for the idea!

Gregory Gesch · March 9th, 2010, 06:02 PM

Daniel or anyone - just out of curiosity does BCC Motion Key create tight masks of only the moving object? I checked out their site but it doesn't say much and, let's face it, anything that might save rotoing is worth knowing about.

Daniel Raebiger · March 10th, 2010, 02:14 AM

unfortunately there is no 'show mask' option :(

Gian Pablo Villamil · March 11th, 2010, 01:57 AM

If BCC Motion Key is delivering a clean background, then do this:

1) Put your original shot through BCC Motion Key
2) You now have a "clean" background with no people in it
3) Put the clean background in your project
4) put the original footage in a new layer over the clean background
5) Apply a difference key - this should give you a nice mask with only the shapes of the moving people
6) Use that mask to key out only the people and drop everything on top of your graveyard scene

Daniel Raebiger · March 15th, 2010, 08:45 AM

Thanks. Great Guide!

March 7th, 2010, 11:14 AM	#1
Daniel Raebiger Regular Crew Join Date: Jul 2007 Location: Landshut, Germany Posts: 143	Reverse Motion Keyer? Hey Guys, I've got a static shot here with two people entering the frame from the left and right, meeting in the middle. For some reason i'd like to replace the background of the shot with a graveyard. In my search for a way to do this without painfully masking the people by hand I've found the BCC Motion Key plugin which can remove moving objects from a frame. It works really well. So i am wondering: if bcc motion key can detect what moves and removes it - is there a way to keep whats moving and remove all the background? Thanks :) __________________ Important notice: There's still soup left!

March 7th, 2010, 08:08 PM	#4
Daniel Raebiger Regular Crew Join Date: Jul 2007 Location: Landshut, Germany Posts: 143	that was sort of obvious. now i really feel stupid ;) thanks for the idea! __________________ Important notice: There's still soup left!

March 10th, 2010, 02:14 AM	#6
Daniel Raebiger Regular Crew Join Date: Jul 2007 Location: Landshut, Germany Posts: 143	unfortunately there is no 'show mask' option :( __________________ Important notice: There's still soup left!

March 15th, 2010, 08:45 AM	#8
Daniel Raebiger Regular Crew Join Date: Jul 2007 Location: Landshut, Germany Posts: 143	Thanks. Great Guide! __________________ Important notice: There's still soup left!

March 7th, 2010, 06:12 PM	#2
Gregory Gesch Regular Crew Join Date: Jun 2009 Location: Brisbane Australia Posts: 114	Hi Daniel. In Effects/Keying there is the Difference Key which is designed for that - though it has variable results especially if there are shadows. If you are getting a clean key from BCC Motion Key (sorry I have never used it) and it creates masks around the moving figures you might be able to go into the mask properties and iether invert them or set them to 'subtract'?

March 7th, 2010, 06:22 PM	#3
Gregory Gesch Regular Crew Join Date: Jun 2009 Location: Brisbane Australia Posts: 114	Sorry about the double post but can't figure how to delete this?

March 9th, 2010, 06:02 PM	#5
Gregory Gesch Regular Crew Join Date: Jun 2009 Location: Brisbane Australia Posts: 114	Daniel or anyone - just out of curiosity does BCC Motion Key create tight masks of only the moving object? I checked out their site but it doesn't say much and, let's face it, anything that might save rotoing is worth knowing about.

March 11th, 2010, 01:57 AM	#7
Gian Pablo Villamil Regular Crew Join Date: Mar 2006 Location: New York, NY Posts: 138	If BCC Motion Key is delivering a clean background, then do this: 1) Put your original shot through BCC Motion Key 2) You now have a "clean" background with no people in it 3) Put the clean background in your project 4) put the original footage in a new layer over the clean background 5) Apply a difference key - this should give you a nice mask with only the shapes of the moving people 6) Use that mask to key out only the people and drop everything on top of your graveyard scene