Motion Capture Technology Computer Graphics

COMPUTER GRAPHICS
MOTION CAPTURING TECHNOLOGY
BY- ROHAN PATEL EMAIL : ROHANHP99@GMAIL.COM 1

Name : Rohan Patel
Enroll : 140170116038
Subject : Computer Graphics
Topic : Motion Capturing
Technology

CONTENTS
• INTRODUCTION
• HISTORY
• ROTOSCOPING
• MOTION CAPTURING TECHNIQUE
• APPLICATIONS
• CONCLUSION

INTRODUCTION
• Motion capture is the process of recording human movement
through specialised cameras and mapping them onto a
character model.
• Motion capture technology involves sensing ,digitalizing, and
recording that object in motion.
• also known as Mo-Cap, Virtual theatre, Real time animation or
performance capture.
• In filmmaking and video game development, it refers to
recording actions of human actors, and using that information
to animate digital character models in 2D or 3D computer
animation.

HISTORY
•Motion capture was first developed in the late 1970’s but it
wasn’t recognised as a revolutionary animation technique
until the mid 1980′s when it was eventually used for
entertainment purposes.
•The technique of “ROTOSCOPING” was invented by Max
Fleischer, dressed in a clown outfit as the live-film reference for the
character Koko the Clown.
•Walt Disney and his animators employed it in Snow White and the
Seven Dwarfs in 1937. From Snow White onwards, the rotoscope
was used mainly for studying human and animal motion, rather
than actual tracing.
BY- ROHAN PATEL EMAIL : ROHANHP99@GMAIL.COM
5

•Later loony toons, movies like Wizards (1977), The Lord of the
Rings (1978), American pop etc were created.
•Video games often use motion capture to animate athletes, martial artists,
and other in-game characters. This has been done since the Sega Model
2 arcade game, Virtual Fighter 2 in 1994.
• By mid-1995 the use of motion capture in video game development had
become commonplace.
• and developer to have its own in-house motion capture studio built into its
headquarters
6

ROTOSCOPING
• A rotoscoping is a device that enables animators to
trace live action movement, frame by frame, for use
in animation.
7

CLASSIFICATION OF MOTION CAPTURE
1. MECHANICAL MOTION CAPTURE
2. THE OPTICAL MOTION CAPTURE
3. THE MAGNETIC MOTION CAPTURE
Generally motion capture can be classified into three
categories :

1. MECHANICAL MOTION CAPTURE
o Mechanical motion capture systems directly track body joint
angles and are often referred to as exo-skeleton motion capture
systems.
o The sensors are attached to the body of performer and each joints
are connected to the angular encoder.

o The value of movement of each encoder (rotation etc..) rebuild by a computer that by
knowing the relative position encoder can rebuild the movement on the screen using
software
o Mechanical motion capture systems are real-time system.
10

Advantages
Offer high precision
Do not depend on external factors such as no. of
cameras
Computes rotations directly
Portable, unlimited range
Less expensive
Can capture multiple performances simultaneously

Disadvantages
External structure unwieldy
Cannot change the configuration, i.e.,
a hand capture can’t be used for an
arm
It is complicated to measure the
interaction of several exoskeletons.

2.THE MAGNETIC MOTION
CAPTURE
 Electromagnetic Motion Capture is one of the more technical types of Motion
Capture relying on transmitters and receivers to track movement.
 performer would wear several magnetic receivers in which transmitters would tract
and calculate movement.
 Performer wears an array of magnetic receivers which track location with respect to transmitter.
 12-20 tracking sensors are placed on a captured subject.
 Tracking sensors output their translation and orientations.
 Divide into two groups
 1. Direct Currant (DC) : Uses square pulses
 2. Alternating Currant (AC) : Uses sin wave pulse

Advantage
NO OCCLUSION
LESS EXPENSIVE THAN OPTICAL
MOTION CAPTURE

DISADVANTAGES
LIMITED RANGE
SENSITIVITY TO METALS
CANNOT PERFORM WITH MULTIPLE ACTORS
CAPTURE VOLUME IS LIMITED

3.The Optical Motion Capture
 The capture is based on optical shooting several synchronized
cameras
 2 to 32 cameras controls by computer
 Operating principle is similar to radar

Working Principle
 The cameras emits the radiation (usually infra red), reflected
by the markers(whose surface is reflected by ultra reflecting
material) and then returned to same cameras.
 These are sensitive to one type of wave length and viewing
markers in the form of white spot videos. Checking the
information of each camera to determine the position of
markers in virtual space.
19

21

Advantages
 Freedom of movement
 High quality capture
 High throughput
 fast sampling (200 fps at a high resolution)
 can capture fast motions
 large capture space
 can capture many markers

Disadvantages
 Occlusion, markers are can be hidden from the
camera
 additional performers will increase occlusion
 may be able to add redundant cameras
 Marker crossover, which marker are you looking at?
 It is more expensive
 Extensive post processing (the marker’s have to be
located and identified
23

APPLICATIONS
Motion capture is being used more and more in films nowadays
Some film characters require the use of motion capture,
otherwise their animation seems fake.
Films that used motion capture technologies are..
Avatar, The adventures of tintin, The avangers, Hulk, Iron man,
Kochadaiiyaan etc…
Movies/Animations

 Avatar Is The One Of The Best Film Ever Used The Motion Capture Technology.
 To achieve the face expressions, actors wore individually made skull caps fitted with a tiny
camera positioned in front of the actors' faces
 This method allows the filmmakers to transfer 100% of the actors' physical performances to
their digital counterparts
25

VIDEO GAMES
• Used to improve gameplay.
• Takes the game to the new heights and make more attractive.
• Very close to real life characters.

MEDICINE
•Eg: gait analysis,
rehabilitatition
•Sports medicine(eg: injury
prevention, performance
analysis, enhancement
MILLITARY
Tracking head movements of
pilots in millitary

Thank you..

Motion Capture Technology Computer Graphics

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