Comment Location:
http://martysimpossibletorememberurl.blogspot.com/2010/10/reading-11-ladder.html
Summary:
LADDER is a subset of Paleo, if memory serves. The paper says, "LADDER allows interface designers to describe how shapes in a domain are drawn, displayed, and edited". Translation: LADDER gets some basic information about the stroke the programmer then plays with (like Paleo). LADDER deals with primitive shapes only, so it can't recognize a drawing of a cat; the programmer would need to use the line information collected by LADDER to determine the sketch is a cat.
LADDER defines a shape "in terms of previously defined shapes and constraints between them". The pre-defined primitive shapes are everything we saw in the first homework except the multiple line types (like Polyline). A sizable portion of the paper is devoted towards explaining the speicifics of the shape recognition, such as the definition of variables, variable values, procedure of recognition, etc.
Discussion:
Since we've already used LADDER (and Paleo) to do the 1st homework assignment and (I think) it went well, I've got no complaints. It organizes strokes with enough diverse information so the programmer can do further recognition on the shape. LADDER claims to have some more complex shapes such as rectangle and diamond. If there was a triangle shape, I definitely would have liked to have seen it for the first homework assignment.
You can make a triangle shape in LADDER. It would consist of three lines with constraints that line1 meets line2, line2 meets line3, and line3 meets line1. It would be cool if LADDER could be extended to patterns, so we could make LADDER descriptions for trusses (we could call it PLADDER).
ReplyDeleteI definitively like the PLADDER idea (and name). I didnt used LADDER for my homework, I made the rules on plain Java over Paleo recognition. But I can see a LADDER solution may have been much easier or at least more general and reusable. It is a very interesting approach if you used LADDER language to generate the truss recognizer.
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