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Masking: Cutting Off Limbs

Posted: Tue, 30th May 2006, 3:37pm

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Oeyvind

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Rating: +10

TUTORIAL
Cutting off limbs in CompositeLab

This tutorial will cover the basics for creating the illusion of limbs (amongst other things) being cut off. It can be used for a viarity of wanted effects, like chopping a head off, ripping an arm out or just simply making something fly. It's up to you! But in this example we'll cover how to cut of a head.

You'll need to shoot the shot this way:
  • Lock the camera
  • Start capturing, and let the actor(s) preform their part
  • Without moving the camera (it's usually best to not touch it at all) start capturing again, but without the actors. This will create a clean backgroundplate for you to use in the compositing of the shot.

This is my original footage that I'll use as example in this tutorial.

Now, to begin with you open up a new project and select the proper settings. Import the video clip, and part it up into two pieces, two seperate tracks. On the bottom track you place the background-shot without the actor who's going to have his\her head chopped off. Over that you place the part where the actor does his\her part and falls down or whatever. Make those two tracks end at the same time and set the out point. (O)


Now you look through the timeline. Find the moment where the actor is supposed to get his\her head cut off. Study the movement carefully and choose an excact frame where the compositing should begin, and the head are starting to leave the neck. ( twisted )


At that excact frame you create a new mask, and make it so that it seperates the neck from the head and covers roughly the head. Already now you might be surprised of how cool it actually looks!


The following is a bit timeconsuming, because now you have to animate the mask throughout the rest of the shot so that it coveres the head. Remember to have the line that seperates the neck properly placed through the whole act. As you can see I've not animated every single frame, but because of CompositeLab's excellent tweaning system the mask follows its motion smoothly.


By now the shot should already look quite impressive, as the head will suddenly disappear and the actor will continue his\her acting to the end of the shot with no head. But it's not finished yet! Now we have to have the head itself being chopped off and fall down to the ground. To do this we need to have another track, a copy of the current upper track. This is done by a simple Copy-And-Paste to the left of the timeline.


Now that you have two identical tracks, crop the new track so that it starts of at the frame where the actor looses his\her head. You won't notice any differense yet.


We want the head to be visible all the way untill it falls out of frame, so you delete the mask. Do not delete the mask in the track below! Only in the upper track!


Instead of the mask you create a new garbage matte which will keep the head as the masked object nomatter how you animate the shot. The Garbage Matte is found under the "Matte" submenu. Now carefully draw the garbage matte around the head. You might also want to add a slight feather to the mask. (Don't worry, the head will be a bit blurry anyway when finished if you're using Compositelab Pro or VisionLab HD) Animate the garbage matte so that it follows the heads excact movements. Choose a length of the head-animation and animate it all the way to that frame where you crop the shot to end.


Now this is the fantastic thing about this: now that you've seperated the head from the rest of the image you're free to animate the head just as you want! So, animate the head so that it looks like it's being cut off the way you want to. I made it fly a bit up into the air, spin around slightly and then fall down to the ground. I also made a little after-jump to increase the realism.
Through the whole animation it's quite cool to add a rotation of the head, so play around with the rotation-wheel. Unless the actors head is in the center of the frame it's best to do the rotation at the same time as the quad-manipulation. Making the animation seem believable might be a difficult task, so play around with it until you're happy about the animation.


The effect is now complete! The basic part of how to make the illusion of a head being cut off is now done..! Congratulations! razz

CompositeLab Pro and VisionLab HD users!
Owners of CompositeLab Pro and VisionLab HD will in addition be able to add motion blur to this effect.

Click on the "Grade" button to have the toolbox show the different grading options. Select the "blur : angle" and give the head-animation a bit motion blur while moving. NOTE! The rotation-wheel will not apply correctly to the finished result because you've rotated the whole clip, so keep an eye on the complete project while doing the motion blur.


And that's it! biggrin

Take a look at the finished shot here! wink

Now you can use this for whatever you want, lightsabre stunts to brutal gunfights. You might also want to add some blood-effects to the incident. I hope this has been an interesting tutorial, and that you're happy about your result!

Oeyvind

Last edited Tue, 30th May 2006, 3:57pm; edited 3 times in total.

Posted: Tue, 30th May 2006, 3:39pm

Post 2 of 22

Redhawksrymmer

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Cool tutorial! You're the tutorial master! biggrin
Posted: Tue, 30th May 2006, 5:14pm

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JT9

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Nice tutorial Oeyvind! biggrin I will give this a try in the demo of VLAB soon biggrin.
Posted: Tue, 30th May 2006, 5:29pm

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Erfa

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Excellent tutorial! And nice animation on that head, since there is no blood it looks really funny. smile
Posted: Tue, 30th May 2006, 8:11pm

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NickD

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Nice tute, Oeyvind. Very helpful smile +1
Posted: Tue, 30th May 2006, 11:43pm

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petet2

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Oh for more time in my life to put the things I learn to use!

Great tutorial.

Thirty years ago I was trying to do stuff like this with super 8mm film and if you wanted to cut off a limb you had to make a fake limb prop and hope your brother was a good shot with the knife!

Even the BBC couldn't do effects like this at that time and now I have a small box sat under my desk that can do it in such high quality. I hope you guys appreciate the tools you have in your grasp these days.
Posted: Wed, 14th Jun 2006, 10:27pm

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Gman 007

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Nice tutorial, i was just wondering how to do that. biggrin
Posted: Thu, 22nd Jun 2006, 2:40am

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PillowBruise

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very nice and rather simple. I went on my own after the masking part at the beginning, and came out pretty nice.
Posted: Fri, 23rd Jun 2006, 10:21pm

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VRBstudios

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All u need r bloodsplats from http://detonationfilms.com/
there's some real nasty ones in there!
Posted: Fri, 18th Aug 2006, 8:38pm

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Horcruxes88

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This is great but i have a problem for some reason you can tell were the mask was drwn becuse theres a grey tinti over the my arm. Well the arm has dissapeare dbut you can see the mask even when i render it. I didnt know if you could tell me why.. Ive workd with masks before and they never did that Please help
Posted: Fri, 18th Aug 2006, 9:14pm

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Wizard

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FXhomer20716 wrote:

I didnt know if you could tell me why.. Ive workd with masks before and they never did that Please help
In short, I believe this has happened due to a difference in lighting between your back ground footage, and the footage that contains your actor (in this case, you). Although you may not have seen any noticeable signs of the lighting being different, it is enough to be apparent when watching the two pieces of footage blended together.

Although this is caused by a change in light, it is sometimes caused by the camera auto adjusting as well. If there are actors in front of the camera when you begin recording, the footage will come out slightly different, as opposed to the footage that was recorded without some one in the frame.

If you can not stop your camera from auto adjusting, you could simply begin recording with out actors in the shot, and then have your actors enter, and begin acting their part. It is more likely the footage will match your back ground footage when doing this, and has worked for me in the past.

You could also correct the changes, or make them less apparent, by grading your footage. This is rather easy in CompositeLab, and can go a long way in making the effect more seamless.

Have fun.
Wizard.
Posted: Fri, 6th Jul 2007, 5:03pm

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Lattestone671

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Great tutorial man! This will help me alot.
Posted: Wed, 15th Aug 2007, 2:52am

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Josh3B

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This is really going to come in handy for my zombie flick- thanks for this! Now we'll have heads blasted, people blown in half... it will be absolute calamity!

JB
Posted: Fri, 24th Aug 2007, 8:53pm

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ary1worldgrw

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hi what a nice tutorial but will u plz make of this tutorial a movie and upload it in any uploading site plz.....
Posted: Sun, 9th Sep 2007, 5:54am

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Rpareyon

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Hey when I put two videos, one on top of the other, it all turns transparent for some reason... plz help!
Posted: Tue, 30th Oct 2007, 9:08am

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Link123456

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Rpareyon wrote:

Hey when I put two videos, one on top of the other, it all turns transparent for some reason... plz help!
Are you even using compositelab? If your using Effects lab it does not have much Alpha channelness so will appear transparent
Posted: Wed, 2nd Jan 2008, 1:38pm

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hynesa02

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can it be fixed? at all mines transparent aswell, im using effectslab!
Posted: Wed, 2nd Jan 2008, 6:33pm

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The Siege

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hynesa02 wrote:

can it be fixed? at all mines transparent aswell, im using effectslab!
You should use Compositelab or Visionlab. Effectslab isn't made for compositing.
Posted: Wed, 2nd Jan 2008, 6:48pm

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hynesa02

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ye i know, id love to...but i cant afford it atm ha
Posted: Sat, 17th May 2008, 4:03pm

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Z films

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Rpareyon wrote:

Hey when I put two videos, one on top of the other, it all turns transparent for some reason... plz help!
you have to go to select movie, you went to import media
Posted: Sun, 25th May 2008, 9:26pm

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Z films

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Thamks for this! I will use this in my new head blowing off extravaganza
Posted: Tue, 10th Jun 2008, 2:59pm

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May the Force be with you

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Nice tutorial, but you could have mentioned green-screening. It's a lot easier, and looks better because of lighting differences in the two shots. Especially by outdoor takes, your technique can be ruined by a few clouds. Of course, this can be evaded by grading the background to match the foreground. Ah well...