Rotoscoping. An affordable alternative to motion capture.
The method is really an extension from traditional cel animation rotoscoping and current animator techniques. Rotoscoping is basically tracing over video footage. There has been a few movies, only one I can think off is, The Lord of the Rings (1978), thats the cel animation one folks. Incidently, the new LOTR, Gollum was animated with both mocap and rotoscoping. Animators who have worked with camera matching and motion tracking (software) will be familiar with this method.
Its basically using a reference video in the background, and manualy tracking the motion and keyframing. The setup I have outlined uses 2 cameras, for front and side views. Depending on your animation you may only need 1 camera. The second camera helps when you have key points (or limbs) that get obscured.
Things you need.
- 2 cmosccd cameras
These are your typical, security or babysitter cam types. Don't need color or sound and look for the made in asia ones, not great but usually alot cheaper and still works.
- 2 tripods
Cheap lightweight types or anything that can prop up the cameras which are tiny and light anyway).
- Video splitter (The ones I found were called quad splitters or quad processors) This is the main cost. The kind that you usually see for store security, that takes a few video inputs and outputs to tv as splitscreen. Again, you really only need the B/W one, so a lot cheaper.
- Video capture card
Dont need a fancy one. I used a GForce4 card with video in. Its crappy 320x240 avi capture but thats all you'll need as your not editing the next blockbuster.
Other items.
- TV (any old one)
- Video cables from both cameras to video splitter, from video splitter to TV and PC for capturing.
- Lots of masking or gaffer tape (okay, you don't need alot but always comes in handy )
- Whiteboard marker/Pencil or scotch tape
- Video editing software (again you dont need fancy one, just typical cut/trim, export avi. There are usable
freeware/shareware ones)
- Ample space to set everything up.
- Actor or person doing the motions.
Okay I think thats all. So very quickly, this is how to set it up and how it works.
General Setup
First, find the spot you're going to use and where you're going to place the person. The amount of space that you need will be determined by the type of motion you're capturing and the FOV of your cameras. Do some tests firsts. Put down a cross on the ground with masking tape. Setup the cameras at the front and side of the spot.
Use the marker/pencil/scothtape and make a cross on the tv screen. Adjust the camera positions until the crosses on the ground and tv line up. This does not have to be spot on. Just abouts is good enough. Depending on the cameras FOV and distance to the actor - the cross on the ground will be at the lower part of your screen so line up the vertical lines. - You can also tape a cross on the actors chest and down the side of the arm, centering the cameras to the chest.
Now, get your actor to do his stuff. Capture the splitscreen output. Once you've captured all you need, the rest is done on the pc.
So, lets say you've captured a cool disco move, lets call it disco.avi, and you captured it at 320x240. I used a quad splitter. which should have front camera,side camera and 2 blank. Bring the video into your editing software. Crop the front camera, which will be 160x120 and scale it back up to 320x240. Yeah, so your actor is nice and smudgy, it doesnt matter as long as you can see all the motion. Save this out as discofront.avi and do the same for the side view.
Load up your 3D software, I was using 3dsmax at the time. Load up the model that has been setup for animations. Set the frame rate and length to that of the video. Load up frontdisco.avi as a background in the front view and likewise for the side view. Now just start keyframing the animation to match up to the movements on the video. I generally start with keyframes every 5 frames then add where required. Its really fast to do since you have the front and side views synced.
Advantages:
- Affordable for indie developers.
- Cheaper and faster than outsourcing mocap services.
- Animations can be fine tuned by lead or art director during the filming.
- Achieve near mocap quality, quickly.
- Good for short sequences
Disadvantages:
- Not very practical for long sequences. As in long, single shot, no cuts kind of thing.
- Animation quality is still dependant on the animator. Secondary motion, or slight nuances may not be picked
up by the animator.
* Apperntly there is also a pc card that works as a quad splitter and captures to hard disk. Probably available form the same people that sell video splitters and cmos cameras.
