The Production Process of Computer Animation

Preproduction

conceptualization and planning
nonvisual tasks (screen writing, casting, and planning the management of the project)
visual tasks (storyboarding and developing the overall visual look of the project)

Storyboards

The creation of early storyboards helps to translate the story and the script into images
During preproduction, storyboards are partly used to fine-tune the storytelling and the time of the action
As this process evolves, the storyboards generally include more production-oriented details such as the final staging, composition, actions, and camera moves

Animatics (Story Reels)

A collection of simple moving images used to visualize how the final project may be structured and timed
A 2-D animatic can be created by scanning single drawings from the storyboard and creating a sequence of images in time
A 3-D animatic use preliminary visual materials like wireframe to visualize a rough cut of a computer animation
Commonly shown to a client or an executive producer for review before production and as production starts

Story Reel example: https://vimeo.com/63444715

Previsualization (previz test)

An approximation that is made of the models and action as close as possible to the final motion in live action projects
Crucial in planning sequences in a movie

The Matrix Reloaded : previs https://youtu.be/KMMeHPGV5VE

Production

Involves a series of standard steps: modeling, rigging, animation, and rendering.

Modeling

Use virtual modeling tools to sculpt objects
Use 3-D digitizer to capture the shape of a physical model directly into the computer program

The task of modeling the geometry in a computer animation project is usually divided by type of model or by scene.

By type of model

Popular with large projects
Models of the primary and secondary characters are assigned to a team
Props and the environments, called set dressing, is assigned to other.

By scene

Better suited for simpler projects
A team is responsible for building of models for a particular shot

It is common to build proxies, or placeholder geometry, early in the process so that animators, riggers, and others can get started while the final models are completed

Rigging

The internal skeletons that are most often used to animate characters are called animation rigs.

These controls are also called IK rigs because many skeletons are rigs or chains of controls that use the inverse kinematics (IK) animation technique.

Animation

Character Animation

3-D character animation done with keyframing techniques starts with rough animation, which consists of blocking the broad motions using placeholder geometry

Effects Animation (Technical Animation)

Effects animation: animation of the natural phenomena, like rain, wind, and fire

Most techniques are procedural and require some or much scripting, therefore also referred to as technical animation

Lighting and Rendering

Lighting involves the placement and fine-tuning of all the light sources in every shot of the film.
The nature of lighting in computer animation is very close to traditional cinematography
Rendering involves the shading of the geometry and oftentimes the developing of special shaders that are used for this purpose

Texture Painting

Most 3-D computer animation projects make extensive use of textures for the geometry.
Painted by hand directly with a digital paint system or
Painted with traditional materials and then scanned
Texture painting and touch-up is usually done by painters, often shared with the visual development team.

Postproduction

Once the images have been rendered, a variety of postprocessing and postproduction techniques can be applied to the images before they are recorded

Computer-generated images can be digitally composited
Computer animation can also be distorted, retouched, processed, or color corrected
When computer animations are completed, they are usually recorded on videotape or film, or delivered in a digital format.

Modeling Concepts

Space, Objects, and Structures

3ds Max labeled width with X, height with Y, and depth with Z.
The point where these 3 axes intersect is the world origin.
The rectangular coordinate system can be used to define specific locations and accurately position the points of objects in 3-D space.
Also referred to as the Catesian coordinate system
Right-handed coordinate system
- Values on the X axis become larger to the right of the origin
- Values on the Y axis increase as the move above the origin
- Values on the Z axis grow as they get closer to us

Points, lines, and facets are the basic elements that can be used to build 3-D objects.
A point can be easily defined by its XYZ position.
A line can be defined by the XYZ location of its two endpoints.
In 3-D geometry, a point is also referred to as a vertex, which is defined by the intersection of 2 or more edges.
An edge is defined by two adjacent surfaces.
A Facet is a planar surface that is defined by the position of its bounding lines.
A 3-D object is usually composed of several points, lines, and facets.

Translation, Rotation and Scaling

Translation

Move an object or group of objects in a linear way to a new location in 3-D space
Can occur along one axis or along several axes at the same time

Rotation

Move an element or group of elements around a specific center and axis
The amount of rotation is usually specified in terms of an angle of rotation (measured in degrees) and a direction of rotation
When rotating an object around its own center, it is possible to reposition that center (In 3ds Max, it is called “pivot”)

Scaling

Change the size and/or the proportion of an element or a group of elements
Can be applied in proportional or a non-proportional mode
- Proportional scaling: resize an object along each axis in equal amounts
- Non-proportional scaling: the object may be resized by different factors along each axis

Modeling Techniques

Geometric Primitives

Geometric primitives are standard shapes that the modeling program can create and manipulate effortlessly and usually from a simple predefined mathematical description.

Can be used to represent simple shapes
Can be used as the basis for more complex, composite 3-D shapes
- Build more complex objects with a variety of utility tools for trimming, attaching, and blending

The standard primitives provided by 3ds Max

Box, Cone, Sphere, GeoSphere, Cylinder, Tube, Torus, Pyramid, Teapot, Plane, TextPlus

Toruses is a 3-D, closed shape that resembles a donut

Sweeping

Sweeping is perhaps the most powerful derivative modeling technique

The basic idea behind all sweeping modeling techniques consists of defining a 2-D outline that is swept along a predefined path.
As the outline is swept, it defines a shape in 3-D space.
The resulting 3-D model depends largely on the complexity of the seed outline and the complexity of the path

Extrusion

Create 3-D shapes by starting with a 2-D outline and extruding or extending it along a straight path along one axis
Sometimes called lofting because the 2-D outlines are duplicated and moved a level up

Free-form sweeps

Some programs also offer the ability to extrude objects along curved paths of any shape and along any axis or combination of axes.
An extrusion that takes place along several axes is sometimes called a sweep, an extrusion on a path, or a free-form extrusion

Lathe or revolve

The surfaces created with this technique are usually called surfaces of revolution.
The software-based lathe tool simulates a real lathe, which is a tool composed of a rotating base on which you place a cylinder of wood that is shaped by placing a steep blade on its surface as the base rotates around its vertical axis.
The software lathe sweeps a 2-D outline around one axis; the 2-D outline may be open or closed.
A new 3-D shape emerges as the 2-D outline is swept along a circular or radial path; it usually remains perpendicular to the sweeping path as they are swept.
The resulting 3-D object is defined by the areas enclosed with the revolved 2-D outline.
2-D outlines that do not touch the axis of sweeping will result in 3-D objects with holes
In these cases, the resulting shapes can be capped or uncapped.

Curved Lines

Lines are used to define the shape of the object and many of its surface characteristics.
Straight lines define the shortest distance between two points
- Defined by 2 endpoints only; may have a slope but no change in angularity (slope is constant -> no curvature)
- Sometimes called polygonal lines
Curves are about subtlety of change and elegance of design
- Defined by several points; deviate from a straight path without any sharp breaks in angularity (slope is variable)
- Sometimes called curve segments
- Also called splines
All splines are generated from a defining polygon -> controlled curves
Each of the spline curves can be quickly characterized by the way in which it is controlled by the control points or control vertices
Control points can control the curvature or tension of a curved line
The structures that control the splines are invisible

Linear splines

Looks like a series of straight lines connecting the control points

Cardinal splines

Looks like a curve that passes through all of its control points

B - splines

Looks like a curved line that rarely passes through the control points

Bezier curves

Passes through all of its control points
The Bezier curve differs from the other splines because it has tangent points in addition to the control points.
Tangent points are used to fine-tune the degree of curvature on a line without modifying the control points.

NURBS (nonuniform rational b-splines)

Does not pass through all its control points
NURBS offer a high degree of local curve control by using weights and knots.
The knots on a NURBS determine the distribution and local density of points on a curve.
One weight is attached to each control point, and they determine the distance between the control point and the apex of the curve.
- Nonrational curve: all control vertices on a spline have the same weight factor
- (B-splines are NURBS with equal weights)
- Rational curve: when the values of the weights on the curve are modified
Manipulating weights on a NURBS curve may improve the subtle shaping of a line, but it usually also slows down the rendering of the final model.

Basic Modeling Utilities

Getting Information and Naming Objects
Locking
Setting a Face
Setting the Center of Objects
Duplicating and Instancing
SettingText
Mirroring
Snapping to the Grid
Volume Calculation
Bounding Box

Advanced Modeling

Curved Patches

A curved patch is a small curved area that can be created from curves.

Complex free-form surfaces are created by merging 2 or more curved patches.
When curved patches that have the same number of rows and columns are merged, the results are fairly predictable.
But merging patches with different numbers of rows and/or columns requires the use of interpolation techniques that modify one of the 2 patches being merged

Subdivision Surfaces

Subdivision surfaces are popular as a flexible solution of modeling surfaces.
There are many ways to go about subdividing a surface: interpolation, averaging, approximation, and insertion of new points.
To be efficient, they are usually based on adaptive approximation (the surface will subdivide only where the topology of the surface requires additional detail).

Subdivision surfaces are defined algorithmically, and many of the algorithms that produce more polygons do so in 2 steps:

Split each surface into 4 facets
Reposition the vertices by doing local weight point averaging

Logical Operators

Logical operators are used to create models by adding and subtracting shapes in a variety of ways.

Union
Intersection
Difference

Trimmed Surfaces

The difference logical operator is usually referred to as trimming
The surfaces created with it are called trimmed surfaces
This technique is especially useful for creating 3-D objects or surfaces with holes

Advanced Modeling Utilities

Beveling

The edged between adjacent surfaces can be customized with great detail with a variety of beveling techniques.
Simple beveling usually works by truncating the hard edge between adjacent surfaces and replacing it with a slanted plane.
The amount of beveling can be controlled by a distance radius, or angle value

Rounding

Rounding is a delicate form of beveling that literally rounds the straight edges or points of an object.
The degree of rounding is controlled by the number of segments or facets that are used to define the smooth transition between adjacent surfaces

Fillets

Fillets create a custom trim that extends along the edge.
Some software programs create fillets by trimming the surface, and others by sweeping a custom 2-D outline along the edge that is being modified

Aligning

Aligning 2 patches usually works by selecting the 2 patches to be aligned and then moving and rotating them until they are aligned a certain way.

Fitting

Fitting utilities get rid of small gaps between surfaces by dragging the 2 surfaces that are not quite touching each other until their edges match each other perfectly.
Fitting is almost always used prior to merging 2 patches.

Blending

Special way of merging 2 surfaces.
Instead of merging 2 surfaces by first making them touch each other and then merging them, blending creates a new surface that extends from each of the 2 surfaces being blended.
The new surface created by blending connects the 2 surfaces, and the smoothness of the blending is controlled with a function curve or by manipulating the control points of the blended surface.

Purging Points

Purging utilities are useful for automatically eliminating excessive vertices in complex 3-D models.
This is usually done by identifying pairs of points that are too close to each other – based on a minimum distance – and deleting one of them.
Manual point-editing is often used in conjunction with purging utilities to fine-tune and adjust the distribution of points in the model.

Deformed and Randomized Surfaces

Shear
Taper
Rotate
Bulge
Radial shear
Radial bend
Bezier bend
Parallel bezier bend