Reading #4

Comment:
chris aikens

Summary:


In this paper, the author introduces the sketchpad, the first pen-based sketching system in 1960s. First chapter of the paper starts with an examples of how to drawing a hexagon from circle and how this can be used to generate a hexagonal lattice. The following parts analyze the capabilities, design and the usage of the system. The 2nd chapter talked about the data structure of the system, actually, all the lines and points are stored to their properties. All things with the same type will be stored in a ring under a generic heading, which contains all the information to distinguish this type from other types. The rest chapters talks about light pen how to track and locate the position; how to drawn lines, circle, digits, etc. to the screen; how recursion can be used for efficient operations like deleting, merging etc; what kind of constrains that user can apply to the drawing.



Discussion:

Actually, I learned Sutherland firstly from Computer Graphics class, since there is a famous Polygon Clipping algorithm "Sutherland-Hodgman" named after him. I just googled, and I am sure it is the same person here.

For this paper,

From the view of Graphics, I can see quite a lot of similar idea. What Graphics concerns is the description the drawing, same as Sutherland stated in the paper "Each time a drawing is made, a description of that drawing is stored". Although most of the aspects in Sketchpad can be easily realized by nowadays tools, like OpenGL with any object-oriented programming language like C++, this is undoubtedly a great breakthrough in 60 years ago.

From the view of sketch recognition, I was thinking, if we can use some Graphics way like Sutherland did in the paper. Would it be more efficient to build a representation/description for object -- like to use a spline to fit to the shape, then check its parameters -- Well, this is another kind of feature, I agree. Just wondering if these are some redundant correlated features in Rubines or others paper.