getting started © juhanita2015. learning objective introduction to the 3d computer graphics 3d...

Getting started

Learning Objective

Introduction to the 3D ComputerGraphics

3D vocabulary

Computer graphics Computer graphics is another form of

art where the creative process andideas are developed and expressedinto visual communication by using the computer.

Computer graphics Computer graphics, in general is categorizedinto three major parts of use:

Image Computer Imagegénération animation manipulation

3D Graphics 3-dimensional

width, height and depth.

Everything in the real world is 3 dimensional

How come then the 3d graphicsgenerated on the computer screens

are flat?

3D Graphics“Two dimensional representations of three

dimensional objects.”

Two dimensional refers to the 2 dimensional screen output ofthese graphics and 3 dimensional objects here refer to theobjects which exist only in the memory of the computer.

They do not exist outside the computer and have no physicalform - they are just a bunch of codes and numbers.

Utah teapot The first modelled 3d object

in history by Martin Newell,a computer scientist.

He sketched on a graph paperwith pencil. Next, the sketch wasbrought to the lab and modelledwith Tektronix storage tube since

there were no 3D packages then.

All processes were completed

by hand.

http://www.holmes3d.net/graphics/teapot/

Utah teapot Data set of the Teapot

3D graphics outputs You may produce artwork in the following forms:

Still image rendering

Web presentation

VRML

Movies

3D graphics outputsStill image rendering

A traditional medium ordinarily used by 3Dartists to express/illustrate ideas.

The output can be in any 2D image filessuch as Jpeg, Tiff, BMP, and TGA.

3D graphics outputsWeb presentation

With new technology, we can browse 3Dpresentations on the web. CULT 3D enables us tobrowse a real time object with realistic real time

texturing and lighting. Other interactive options can also be added for

higher sophistication.

http://www.cult3d.com/

3D graphics outputsVRML

Virtual reality modelling language is one ofthe well-known formats for navigating 3Dobjects on the web.

It is the first technology for 3D webnavigation.

http://www.pinecam.com/PinecamVR/portfolio.html

3D graphics outputsMovies

You may want to render your work inanimated clips instead of in still images.

Graphics artists’ favourites are avi, mov,mpeg file format.

3D creation Vertex

Lines/edges

3-sided polygons

objects

Vertex 3D geometry is composed of fundamental

shapes that provide building blocks.

The atom of the 3D World is the vertex, a point inspace.

The vertex is the first dimension, without width orlength, simply positioned in space.

Lines: The Second Dimension

The points on the line contain information thatdetermines whether they are straight or curved.

In the 2D world these lines can create open orclosed shapes and paths used for 3D modelingand animation.

2D text Text is another type of 2D object.

Three-sided polygons The basis of objects creation in 3D space

Face - three vertices join to create a triangular face

Edge - the line joining each of the two vertices

Polygon- can be two or more joined contiguous faces.

Objects Anything that appears in the viewport is either

an object or a sub-object selection within anobject.

Surface and Object Properties Faces have additional information to define the

smoothing between edges.

Smoothing groups produce smoothing, so a ball looks like a ball rather than a collection of triangles.

3D axis and coordinate system The position of 3D vertex is give three numeric

values for X, Y and Z.

These values are measured from a central point,the world space origin (0,0,0)

3D space consist also of three imaginary lines whichdefines direction. These lines are called axis.

3D Coordinate System3 most common types of coordinate system available in 3D Studio Max.

World coordinate system (fundamental) : remainthe same regardless the viewport.

View coordinate system : use the viewport as the basisfor the X, Y and Z axis and remain the same no matter howyour viewport on the 3D scene changes.

Local coordinate system : the point about which anobject transform (move, rotate, scale) is called pivot pointor local origin of the object. The local origin of an object incontrast is the center of the local coordinate system.

3D viewports

Whenever you look at your scene in 3D whetheryou are building your scene or ready to renderimages, you are looking through a camera.

Your field of view is restricted to what you cansee through that lens.

3D viewportsBy default, 3ds Max has cameras that let youview your scene in a panel:

perspective viewport

orthographic viewports

Axonometric viewports

Orthographic viewports side, top, front that correspond to the default

scene views.

Flat, Plan, or Elevation

F, L ,T

3D viewports Axonometric viewport

User viewport

Perspective viewport Human eye, POV , more natural

Vanishing point

Distortion - scale and position

3D Transformations3 operations collectively are called transformations :

move (w): an object about in space.

rotate (e): tilt an object or change the directionin which it is facing.

scale (r): change its size.

Move relocate an object in space

in order to move an object to its final position, itcan be moved in all 3 axis or constricted tocertain axis

Rotate rotate an object into other orientation.

rotations, like translations are usually written as aset of 3 values, on each for the X rotations, the Yrotations and Z rotations.

Rotate (90, 0, 0) means rotate X 90 degreesaround and nothing around Y and Z.

Coordinate Systems and Rotation When you rotate an object, three factors influence the way it turns :

which coordinate system (world, view, local oruser) is currently active.

the location of the rotational center point (pivotpoint)

which axis is chosen to rotate the object around.

©

ScaleChange the size or the proportions of the object

proportional scale/uniform scale

non-proportional scale/non-uniform scale

Proportional scale/ Uniform Scale scaling factor is the same for all axis

the overall size changes but the originalproportions of the object remain the same.

resize

Non-Proportional/ Non-Uniform scale An object is scaled on one or 2 axis at a time.

Squash and Stretch

Scale

Scale if scaling is by a negative number, means that

the object will be flipped or invert.

mirror

Cloning Duplicating objects in 3D

Methods of cloning: [Shift]+ Transform

Snapshot

Array

Mirror

Spacing Tool

Cloning There are three types of clone option:

copy, instance and reference

A copy is a simple copy and they are not linked inany way.

An instance of an object means that modifying onewould modify the other.

A reference is a hybrid between the two. If youchange any parameters within the modify stack of

either the clone or the original, changes would beduplicated. If you add modifiers to the original, thiswould also be applied to the reference also.However, if you add modifiers to the clone, theoriginal is NOT affected. Basically, the clone is areference to the original.

Cloning

© mcyuen2011

© mcyuen2011

© mcyuen2011

Further Reading http://movielibrary.lynda.com/html/modPage.asp?ID=287