ATEC 6351.001 Procedural - PowerPoint Presentation

Slide1

Procedural Animation

Introduction

to Procedural Methods in 3D Computer

Animation

Dr. Midori KitagawaSlide2

In class

Pay attention

Take notes

Learn

Be ready for a pop quizSlide3

Lecture 2: 3D animation foundations

What is procedural animation? -- Three types of 3D computer animation

World space vs. object space

Order of transformation

Pivot

HoudiniSlide4

What is procedural animation?Three types of 3D computer animation

Keyframe animation

Motion capture animation

Procedural animationSlide5

Keyframe animationSlide6

Keyframe animation

Keyframe

is a drawing of a key moment in an animated sequence, where the motion is at its extreme.

Inbetweens

fill the gaps between

keyframes

.

Every motion is created by animators.Slide7

Keyframe animation

To produce

keyframe

animation

, the animator builds the behavior of a 3D model by keying parameter values in frames where the values are at their extremes. Slide8

Keyframe animation

Based on traditional

hand-

drawn

2D

keyframe

animation

method.

Animation is manually produced from scratch.

Examples:

Pixar

and Blue Sky animationsSlide9

Motion capture animationSlide10

Motion capture animation

To produce a

motion capture animation

, the motion of a capture subject is recorded as 3D data and applied to a 3D model.

The

animation is produced from the capture subject’s movement. Slide11

Motion capture animation

Although

no 3D data is involved in rotoscoping, motion capture technology is sometimes referred as

“devil’s

rotoscoping

.”

Examples: CGI

characters in live action

films, 3D animations and gamesSlide12

Procedural animationSlide13

Procedural animation

To produce a

procedural animation

, the animator defines a procedure or a set of operations to be

performed.

Each

operation can generate or alter data that passes through it and can be conditionally or non-conditionally executed. Slide14

Procedural animation

With

some procedural methods (e.g., particle systems, rigid dynamics and flexible dynamics), the user specifies a set of rules, initial conditions and parameter values and runs

simulations

.

Physics-based animation

is a subset of procedural animationSlide15

Procedural animation

Procedural

methods can be used in any

part of production

pipeline to

produce geometries,

textures, lights, rigs, animation, composites, sounds and other elements.

Examples: visual effects (e.g., smokes, steam, fire, clouds, dust and water) in live action films and 2D/3D animations.Slide16

World space & object space

Scene

is built with an arbitrary number of objects, lights and cameras in the

world space

, which is also called the

world coordinate system

or

global coordinate system

.

Each

object

is generated in its object space, which is also called an object coordinate system or local coordinate system. Slide17

World space & object

space

in

Houdini

World space

is

called

the

scene level

or

object

level.Object space is called the geometry level or

SOP level

.Slide18

Houdini: Scene level and geometric container objects

Geometry container object

is often simply called “object.”

Objects,

cameras and lights

define a

scene

in the scene level. Slide19

Houdini: Geometry level and surface nodes

Surface nodes

are also called

Surface Operators

or

SOPs

.

SOPs

in the geometry level

define the geometry

inside the geometric container object. Slide20

World space & object space

Object space and world space work together.

For

instance, if the

geometric center

of an object is at the origin of its object space and if the object is placed at the origin of the world space,

it

will be centered at origin of the world space.

However, if

the

geometric center

of an object is not centered at the origin of its object space, it will be off-centered in the world space even if it’s placed at the origin of the world space.Slide21

Global transformation vs. local transformation

Transforming an object

in the scene level is considered as

global

transformation animation

.

Transforming a

geometry in the geometry level is considered as

local transformation

or

deformation

.Slide22

Order of transformation

Specifies

in what order transformations are applied to an object.

Changing the

order of

transformation yield

different results. Slide23

Pivot

Transformation origin

Pivot is at

the origin of

local space by default.

Pivot can

be

moved.

In Houdini, use move the pivot in a Transform SOP.

Handles tool

and

Insert Slide24

Week 1: Houdini stuff

Houdini contexts

Linking panes

Hotkey quick reference

Maya transition guide

File organizationSlide25

Houdini contexts

Major parts of Houdini (contexts) and corresponding node

networks:

/ch

CHOP

(channel operators) network

/img

COP

(composite operators) network

/obj

Objects, cameras, and lights/obj/geo SOP (surface operators) network/out ROP (render outputs)/part

POP

(particle operators) network

/shop

SHOP

(shader operators) network

/vex

VOP

(VEX operators) networkSlide26

Linking panes

If panes in Houdini desktop are linked by the same number,

when you move to

a different

part of Houdini in one pane, all the other panes follow

you.

If panes are not

linked, a big confusion can happen.Slide27

File organization and scripts

Scripts to create folders

from inside

Houdini work on Linex and Unix (OS X) machines and help you name folders and files in a systematic manner, i.e. help you organize your project.

Unfortunately

these scripts

do not

work on Windows machines.

Working

in the Linex/Unix environment is highly recommended but not required for this course.

No matter on

which OS you are running Houdini, name folders and files systematically and organize them efficiently. Slide28

Saving animation frames

If you are not using Unix/

Linex

, select a folder and set a file name (e.g., A1.$F4.pic) using

Choose File

.

Override Camera Resolution lets you scale the frame size.Slide29

Creating an animation file

In Houdini’s main menu (top left), chose Render ->

MPlay

-> Load Disc Files...

In Load Image, select animation frames.

In

MPlay

, chose File -> Export -> Video for Windows 64.bit.

Above turns .pic files into an .

avi

file.Slide30

Houdini reference & guide

Print out

Hotkey quick reference

and

keep in your

notebook

so that you can look at it whenever you need it.

You may find

Maya

transition guide

useful to understand Houdini’s contexts if you are a Maya user.Slide31

One more thing…

In a View pane, you can:

l

ook through a camera or a light

turn on

Tie View to Camera/Light

option

via a popup menu that shows up if you click here.