Reading Assignment: Sketchpad: A Man-Machine Graphical Communication System

Reference Information
Title: Sketchpad: A Man-Machine Graphical Communication System
Author: Ivan E. Sutherland
Citation: "Sketchpad A Man-Machine Graphical Communication System", Ivan E. Sutherland, DAC '64 Proceedings of the SHARE design automation workshop, pp. 6.329-6.346, ACM New York, NY, USA, 1964.

Summary
This paper discussed Sketchpad, a system designed for allowing users to create line drawings on a computer. The interaction was accomplished by using a light pen for indicating points on the screen and a set of push buttons for accomplishing various commands. The image could be created, manipulated (such as zooming and rotating), and observed on a display screen. An image can consist of any number of subpictures consisting of various symbols.  Instances of drawings can be copied. In addition, constraints can be applied to parts of the drawing in order to apply mathematical and geometrical conditions to the image. The structure of the pictures is stored in memory using a ring structure for maintaining the information about a drawing. A generic, hierarchical structure was used for implementing Sketchpad, in which generic functions exist that call more specific subroutines, such that specific operations can be easily added to the system and be called by the generic functions.

The system is designed to aid users with designing and drawing images. It is useful for storing and modifying drawings, increasing understanding of complicated designs, and creating repetitive drawings. In particular, it is useful within fields that could benefit from an easy way to understand and duplicate images, such as engineering.

Critique
Sketchpad seems to be a very important development in computer science, particularly in the areas of sketch recognition and human-computer interaction. Reading about it now, the use of push buttons seems rather out-dated and cumbersome compared to the touch screens that we currently have, but the ability to use a computer to create drawings had to start somewhere. It introduced a novel way of interacting with computers, using a light pen and push buttons to create images on a screen. This is a form of interaction that is often taken for granted in current times, where pens and fingers can be used with touch screens to draw out images with a computer. It is amazing to think that Sketchpad provided these abilities to draw and manipulate images on a machine back in 1964. This paper really shows how far we have come in that time, and yet the similarities that occur despite the time passing shows the importance of the ideas discussed with the Sketchpad system. It mentioned ideas that are now fully fledged systems that are used on a day-to-day basis in many different fields, such as software for aiding both artistic drawings (such as animations) and engineering designs (such as bridge design, circuit design, etc.). Reading this paper makes me interested in learning just how the ideas mentioned in this paper affected the future of computer science and how we have gotten from a system like Sketchpad to the systems that we have today.

I also found it interesting that a generic structure was emphasized for the implementation of Sketchpad, such that a hierarchical structure exists going from general to more specific functions. This was done to provide the ability to easily extend the system. While these ideas have been around for a long time, they are continuously being highlighted in many programming methods today, specifically with object-oriented programming approaches.