Reading #4: Sketchpad: A Man-Made Graphical Communication System (Sutherland)

Comments on others

Sam

Summary

In this paper Ivan Sutherland invented the computer graphics.
Although this first line summarizes the unbelievable work of this paper I will try to make a summary without reproducing the whole thing:
The main topic of this paper is The Sketchpad user interface. This is a graphical user interface that allows the user to draw and manipulate shapes on a screen monitor with the use of a light pen. The Sketchpad system runs in a TX2 computer which has several peripherals like switchboards and knobs, along with a 7“ display and a light pen that allows the user to interact with the program.  Unlike actual graphics tables it was not pressure sensitive so the way of “lifting” the pen was by moving it fast enough for the computer to lose track. Also physical buttons allowed the computer to know which shape the user was intending to draw, for example a line or a circle. More importantly he introduced the ring structure which allowed the computer to represent and store graphical components in a way that allows efficient operations on the shapes.  The use of instances and sub pictures was other of the great outcomes of this system.  This object oriented design allows building shapes upon shapes and consistently maintaining the structure of all instances the same independent of size and rotation. Another important result was the use of constraints over a shape, such that the user can input the constraints and the computer will recalculate the shape to satisfy the constraint if possible and display the resulting shape. The author concludes noticing the advantages and disadvantages of using sketchpad as a design tool. He notes that for some complex drawings such as circuits it is only worthwhile to use sketchpad if you can further obtain something else besides the drawing (e.g. a simulation) however in repetitive patterns sketchpad showed very valuable.  He also addresses various possibilities to continue the work on sketchpad such as 3D drawings.

Discussion

In many papers the important part goes around the experiments done on existing software and techniques and the results obtained by these experiments, having the conclusions as a very important part of the paper. However I think that the Sketchpad and the work behind it are the main characters of this paper, leaving the results and conclusions to be almost shallow compared with the real impact this work had on the computer world. One may read this paper without mayor shock knowing that most of the drawing tools nowadays can do similar things, going from PowerPoint to AutoCAD. But when you see the date of this paper you understand that all of those tools are a mere reproduction of what Sutherland invented here. The breakthroughs of this research cover a wide set of fields in Computer Science, such as object oriented programming, human computer interaction, and of course computer graphics. The paper is cited directly by more than 400 authors [CiteSeerX] and I think the work behind it may have inspired several other thousands. After watching the video of its demo I think that even now, 50 years later it is still an impressive system that is just beginning to have commercial matches like the ipad interface.