Introduction to Motion Capture

Motion capture (MoCap) is the ability to track and record your motions and transferring the movement onto an inanimate object in order for it to recreate the same movements and bring the shell to life. The reason for why the actors are recorded rather than simply animate the object is because by using MoCap we are able to recreate realistic human movements in the most efficient way. It allows us to map parts of the face or body and place it onto the character in order to create movement. Early Motion Capture started out as a technique called Rotoscoping which was invented by Max Fleischer in 1915 and used in his series called ‘Out of the Inkwell’ although it wasn’t until 1917 he patented the idea.

Rotoscoping allowed animators to mimic realistic movements by using photographs or film as a guide when drawing characters in order to create life-like animation. Some of the most famous instances in which rotoscoping was used was within Disneys ‘Snow White and the Seven Dwarves’, but also Looney Toons, Gulliver’s Travels (1938) and even China’s first animated film which was titled ‘Princess Iron Fan’ (1941).

Rotoscoping was then taken one step further with the development of Motion Capture which was used during the 1980’s onwards. Professor Tom Calvert at Simon Fraser University decided it would be a good move to attach electronic sensors onto a body in order to track movement.

These days we are able to do a wide range of things with motion capture which within itself hold a lot of different techniques to obtain the best results. Some examples of type of motion capture include mechanical, optical, magnetic and inertial. Within this post I will discuss Mechanical and Optical motion capture, and hopefully will follow this post up with definitions of inertial and magnetic.

Mechanical motion capture is where the actor wears a basic suit which is covered in metal pieces in the style of a basic skeleton. This is also refered to as exo-skeleton motion capture. Some of the positive uses for this particular type of motion capture is that there is never any interference due to light and magnetic fields. This is because of the suit picking up the movement solely from the actors movement and the response to the sensors which are placed within the suit. Some of the disadvantages of using mechanical motion capture include instances such as in order to use this type of motion capture the actor must remain on the floor. Another disadvantage to using mechanical motion capture over other motion capture alternatives is that the equipment must be regularly be calibrated as the data sometimes shifts.

mechanical_motion_capture

Here is a video which I found while browsing YouTube of mechanical Motion Capture being used within 3dsmax.

Optical motion capture is where the actor will wear reflective dots which are tracked by cameras. This technique allows movement to be picked up through lights or LED’s which are placed on the actor’s body. The movement is then picked up through a large amount of cameras which then triangulate the data to give the movement. This information is then sent to the 3D software allowing you to animate your character. Some of the advantages of using this particular type of motion capture is that it allows the actor to feel fewer restrictions on their movement giving better results. Another advantage is that the data collected is really clear if conducted in the correct settings making animating the 3D model easier. A disadvantage of using Optical would be that other lights could interfere with your suit causing inaccurate results which would greatly effect the outcome of the project. Another issue with optical motion capture is that it is more expensive than other alternatives such as mechanical.

optical motion capture

I thought I would round this post off showing some games using optical motion capture in order to give an idea at the capabilities of what motion capture can really give to a game.

Beyond: Two Souls –

Red Faction Armageddon –

Batman: Arkham Origins –

 

 

 

 

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