Welcome Mahith

Computer Animation & Techniques Seminar by Mahith Mohan Mahith

Name derived from “Anime” means life. Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of motion or life. Name derived from “Anime” means life. It’s just an optical illusion of motion due to persistence of vision Mahith

Simple Example A ball bouncing from just 6 frames Mahith

For better smooth transition we must have higher frame rate. Frame Rate: No. of frames in unit second Film 24 fps NTSC TV 30 fps (interlaced) PAL TV 25 fps (interlaced) HDTV 60 fps Computer ~60 fps Mahith

Classification of animation techniques Traditional animation Stop motion Computer animation Classification of animation techniques Mahith

Traditional Animation Also called Hand drawn animation Or Cel animation Pictures are drawn for each frames. The animators' drawings are traced or photocopied onto transparent acetate sheets called cels ( celluloid transparency) The completed character cels are photographed one-by-one onto motion picture film against a painted background by a rostrum camera. Mahith

Example Mahith

Walt Disney Walt Disney, an American cartoonist and film producer, started an entertainment empire with his creation of animated movies and world-renowned amusement parks. Disney appears here at his drawing board in 1950 with a drawing of Mickey Mouse, his most famous cartoon character. Disney won an honorary Oscar (Academy Award) in 1932 for his creation of Mickey. . Mahith

Stop Motion Animation Stop-motion animation is used to describe animation created by physically manipulating real-world objects and photographing them one frame of film at a time to create the illusion of movement. Mahith

Example Mahith

Computer animation Computer animation contains a variety of techniques, the unifying factor being that the animation is created digitally on a computer Mainly 2 types- 2D animation 3D animation Mahith

Animation Sequences Storyboard layout Outline of action Step 1: Storyboard layout Outline of action Consist set of rough sketches Mahith

Animation Sequences Step 2: Object definition Objects are defined in terms of basic shapes. Associated movement of each object are specified with the shape. Mahith

Animation Sequences Key frame Specification Step 3: Key frame Specification Key frame is a detailed drawing of the scenes at a certain time. Mahith

Animation Sequences Determined by the media to be used to display. Step 4: Generation of in-between frames. Frames between the key frames. Determined by the media to be used to display. Mahith

1’ 2’ Key frame k+1 1 2 Key frame k In-between frame Mahith

Raster Animation Raster animation is the most basic type of computer animation. It involves creating an image, and then using a computer to put that image in motion  Raster based animation frames are made up of individual pixels. These pixels each contain information about the colour and brightness of that particular spot on the image Mahith

Example: Step 1 (erase) Step 2 (move) Step 3 (draw) Ship is redrawn in background color Move ship x’ = x + Dx y’ = y + Dy (x,y) (x+ , , y+ Dy) (x’,y’) Mahith

Mahith

Color-table transformation Simple 2D animations can be easily implemented using colour lookup table. Here we set the successive blocks of pixel value to colour table. Object as “on” rest as background color. Later successively positions along the path is changed to “on” and older position to background color. Mahith

Computer Animation languages Key frame Systems: Designed simply to generate the in-betweens from the user specified key frames Each object is formed with set of rigid bodies connected by several joints with limited degree of freedom. Mahith

Computer Animation languages Parameterized system : Object-motion characteristics are specified as a part of the object definition like Degree of freedom Motion limitation Allowable shape changes …. Mahith

Computer Animation languages Scripting System: Object specifications & animation sequences are defined with a user-input script Mahith

Morphing Transformation of object shape from one form to another is called Morphing ( Metamorphosis) Mahith

Key frame Key frame In-between frame Three frames form a morph from George W. Bush to Arnold Schwarzenegger showing the mid-point between the two extremes Mahith

Linear interpolation for transforming triangle into a quadrilateral 1’ 2’ Key frame k+1 1 2 Key frame k Halfway frame 4 4’ added point 3 3’ Mahith

General preprocessing rules for Equalizing key frames Using edge count: Let Lk & L k+1 no of line segment in 2 consecutive key frame. Then Lmax =max(Lk ,Lk+1 ) , Lmin =min(Lk , Lk+1 ) And Ne = Lmax mod Lmin Ns = int(Lmax / Lmin ) Then the preprocessing is accomplished by Dividing Ne edges of keyframemin into Ns +1 sections Dividing the remaining lines of keyframemin into Ns sections. Mahith

General preprocessing rules for Equalizing key frames Example for by using edge count: 1’ 2’ Key frame k+1 1 2 Key frame k 4’ 3 3’ L k =3 L k+1 =4 L max =4 , L min =3, N e = 1 , Ns =1 Divide 1 (N e ) edges of keyframe k (keyframe min ) to 2 (N s+1 ) section Since Ns =1 leave the remaining sections. Mahith

General preprocessing rules for Equalizing key frames Using vertex count: Let Vk & Vk+1 no of vertex in 2 consecutive key frame. Then Vmax =max(Vk ,Vk+1 ) , Vmin =min(Vk , Vk+1 ) And Nis = (Vmax -1) mod( Vmin -1) Np = int((Vmax -1) / (Vmin -1) Then the preprocessing is accomplished by adding Np points to Nis line section of key framemin. Adding Np -1 points to the remaining edges of key framemin Mahith

General preprocessing rules for Equalizing key frames Example for by using vertex count: 1’ 2’ Key frame k+1 1 2 Key frame k 4’ 3 3’ V k =3 V k+1 =4 V max =4 , V min =3, N is = 1 , Np =1 Add 1 (N p ) point to 1 (N is ) line of keyframe k (keyframe min ) Since Np -1 =0 leave the remaining edges Mahith

Simulating Accelerations It perform non linear spline interpolation Here the speed is not constant Non linear path is taken at the in-between frames. To stimulate acceleration we adjust the time spacing for the in-betweens Mahith

For constant speed we use equal interval of time spacing. Let consider key frames at times t1 and t2 and having n in-between frames between these. then dt= (t2 – t1)/ n+1 And time for any in-between as: tBj = t1 +j* dt For accelerating we can use functions like 1-cosq, 0< q<p/2 Then time for any in-between is: tBj = t1 +dt ( 1-cos(jp/2(n+1) ) Mahith

Motion Specifications Direct Motion Specification: Explicitly give the rotation angles and translation vector. Then transformation matrices are applied to transform coordinate positions . Or we can use approximate equation to specify some motion. Mahith

Path of a bouncing ball Mahith

y(x) = A sin(wx+ q0 ) e-kx where A =initial amplitude w = angular frequency q0 = phase angle k= damping constant This show the path of a bouncing ball acquired from damped sine function Mahith

Goal-Directed Systems Referred as goal directed because they determine the specific motion parameters given as the goals of the animation. At the opposite extremes we specify the motions in general terms which describes the action. Later input directives will interpret in terms of component motion. Mahith

Kinematics Specification Determines parameters needed for a jointed, flexible object to achieve a pose. Also factors in maintaining balance, joint angle limitations, and collisions between the body and limbs. And all this will be mentioned in kinematic description of the respective points. It’s alternate approach is inverse kinematics. Mahith

Inverse Kinematics Here we will mention the parameters at the initial & final positions of object only. Rest motion parameters are computed by the system. Disadvantage: There is no general analytical solution. Must be solved through non-linear programming techniques. Mahith

Dynamic Specification Here force acting on the body will also mention with the motion parameters. Referred as Physically based system. Motion is obtained from the force equations like Newton’s Law etc. It give realistic effects in motion. So it is used in case of complex rigid body system and some non rigid bodies like cloth etc Mahith

Motion Capture A person wears sensors near each joint Computer software records positions, angles, velocities, accelerations, and impulses for all sensors Typically captures sub-millimeter positions Mahith

Advantages: Disadvantages: Faster than manually creating animations Can have much more natural looking motions and catch all movements of the object. Disadvantages: Can’t do anatomically impossible motions Motion is restricted to the laws of physics. Sensors attached to the skin can shift out of position during human movement causing real performance to differ from data recorded. Mahith

Applications of computer animation Special Effects (Movies, TV) Video Games Virtual Reality Simulation, Training, Military Medical Robotics Visualization Communication Mahith

Visit : www.mahissworld.co.cc Mahith