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:

ACM: http://portal.acm.org/citation.cfm?id=1084450

IEEE Xplore: http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/10086/32319/01509135.pdf?temp=x

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: http://www.surveygizmo.com/s/78771/facebook-interface

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.