Principles of traditional animation applied to 3D computer animation

As the title of this post reveals, I’m going to present a paper about principles of animation that should be applied to 3D computer animation and that are useful in the design of 3D interfaces. The paper was written by John Lasseter, the Chief Creative Officer at Pixar and Walt Disney Animation Studios, and can be downloaded through the ACM website.

John Lasseter gives an historic overview over the the 11 principles of traditional animation defined by the Walt Dísney Studio and then gives an explanation of each one of the principles, relating them to the field of 3D computer animation. Next is a summary on some of the principles presented in the paper:

Squash and StretchDefining the rigidity and mass of an object by distorting its shape during an action
This is the most important principle and says that when an object is moved the movement emphasizes any rigidity in the object. The squash position represents when an object is flattened by an external force or when the object is constricted by its own power. The stretched position will show the same form in a much extended condition.  One important rule about squash and stretch is that the volume of the object has to remain constant during the movement or else the object would look as it had shrink or grown during the process. This principle defines the rigidity of the material that compose the object, i.e. depending on the level of stretch and squash the object would look as is made of different materials.

TimingSpacing actions to define the weight and size of objects and the personality of characters
It represents the speed of an action, giving meaning to the movement and defining how well the idea behind the action will read to an audience. It also reflects the weight and size of the object, as well emotional meaning. It’s important when defining the timing of a scene, to make sure that the audience is capable of reading and understanding the meaning of it as fast as is being shown. Another aspect related to timing is the weight of the objects. A heavy object will have a slower acceleration and deceleration than a light object, and will take a bigger force to change is motion. Timing can also give a feeling of size and scale to an object, by making a huge object with enormous mass to move slowly and a   small object with a small mass to move quickly. Last but not least, timing can show the emotional state of the object by varying the speed of his movements, indicating whether the character is lethargic, excited, nervous or relaxed.

AnticipationThe preparation for an action
Anticipation is used to catch the audience’s eye and to prepare them for what the next movement will be before it happens. The amount of anticipation used considerably affects the speed of the action which follows it. If the audience expects something to happen, then it can be much faster without losing them. This principle is also used to direct the attention of the audience to the right part of the screen and at the right moment, preventing the audience from missing some vital action. Anticipation can also emphasize heavy weight, as for a character picking up an object that is very heavy. An exaggerated anticipation, like bending way down before picking up the object, helps the momentum of the character to lift the heavy weight.

StagingPresenting an idea so that it is unmistakably clear
Staging is the presentation of an idea so it is completely and unmistakably clear, whether it’s an action, a personality, an expression or a mood. To stage an idea clearly, the audience’s eye must be led to exactly where it needs to be at the right moment, so that they will not miss the idea. That is accomplished trough staging, anticipation and timing. One important aspect, when staging an action, is that only one idea should be seen by the audience at a time. Due to that the object of interest should contrast from the rest of the scene, preventing the user of overlooking the idea being transmitted when there is a lot of action happening at once.

A Graphics Toolkit Based on Differential Constraints

This paper is in the vein of the last one I posted, talking about a graphical toolkit called Bramble that also uses constraints. The author of the paper is Michael Gleicher and he outlines the main characteristics of Bramble, showing also what set it apart from other existing graphic toolkits of that time.  Being the big differences the fact that it uses a differential approach and the fact that it allows non-linear constraints, such as distance and orientation, in addition to simple connections. The paper can be obtained through the following link:

Bramble uses a differential approach, in which constraint techniques are used to support direct manipulation i.e. interactions where objects move with continuous motion that are coupled to the user’s actions, such as dragging.

The differential approach used in Bramble aims to provide more flexible methods for the manipulation of graphical objects by permitting constraints and controls on aspects of objects, rather than just directly on their parameters, and permitting these constraints and controls to be combined. Allowing graphical objects to provide the positions of points as outputs without knowing what will be connected, and interaction techniques that can be defined in terms of point positions, without knowing what types of objects these points come from.

The differential approach also permits users to control how combinations of aspects evolve over time, being that aspects can either be driven towards a particular value, or forced to follow a moving target. Those basic differential interactors serve as building blocks for interaction techniques. More complex differential interactors are created by rules which switch a basic interactor on and off as needed. The range of interaction techniques results not from extending this set, but rather from the aspects to which they are applied and how they are switched on and off.

A User Interface Toolkit Based on Graphical Objects and Constraints

This is a paper from Pedro A. Szekely and Brad A. Myers that describes a user interface toolkit called Coral (Constraint-based Object-oriented Relations And Language). Coral uses constraints to manage the relationships between the graphical objects on the screen and the application data structures that they represent. The input from the mouse and keyboard is also not handled by the graphical objects themselves, but by special input handling objects called interactors. This paper can be obtained through the ACM site, in the following link:

Even though the paper is centered in Coral, it gives some insights for the construction of interfaces in which it’s whether recommend or required the use of constraints to obtain a good software product.

  • The use of a hierarchy of graphical objects facilitates the creation of new classes of objects, because the new graphical objects can inherit the complex mechanisms already implemented or override it to their specific needs.
  • Another aspect is defining constraints that can be applied to list of graphical objects and making them reusable so that different sets of constraints can be applied to different instances of the same class.
  • Last but not least, the fact that Coral uses mechanisms call Active Values (data values plus a list of objects and procedures that depend on that value) to provide a clean separation between the user interface and rest of the application. This is a very important aspect in the developing of applications, because allows the application and the interface to evolve without having the burdens that would come with the tact that they were tied to each other.

3D Information Visualisation: An Historical Perspective

This paper gives an overview over the use of 3D Visualisation of digital information and the historic background of perspective in that field. It was written by Theodor G Wyeld and it was presented in the Ninth International Conference on Information Visualisation (IV’05). The paper can be obtained through the following links:


IEEE Xplore:

Some ideas present in the paper after the break

Motives and Uses of Facebook

This paper is about an investigation done by Adam N. Joinson on the uses of the Facebook and the gratifications users derive from those uses. The paper can be obtained through the following link:

Some ideas present in the paper after the break

The survey

Today I’ve launched a survey that will help me answer, at least get some insights, on what do users think about the interface of facebook. One more thing that the survey will do is show if users have used a 3D web interface to view the content of a site, and what they think about it.

The link for the survey is the following:

The Beginning…

This post marks the beginning of me blogging about the progresses made and the tribulations that occur on the development of my master’s project. I’ll do my best to update the site as often as possible, so anyone can read about what’s happening on the project and hopefully find the papers that will be posted interesting.