DrawCAD: mouse-sketch-based engineering drawing

While there has been a lot of work on freehand drawing programs, robust programs which are easy to learn are still not available. We feel our program DrawCAD takes significant steps in this direction. Two dimensional drawings are sketched by the user using the mouse; DrawCAD analyzes the sketches and infers the intent of the user and produces beautified drawings. DrawCAD also infers and maintains constraints between various elements of the drawing. Supported constraints include horizontality or verticality of lines, tangency between arcs and lines, parallelism/perpendicularity between lines, equality of angles or line segment lengths. Some of these constraints are inferred as the user draws, and some can be explicitly added using well known conventions of Euclidean Geometry (e.g. putting a wedge to indicate perpendicularity). The key idea in this is to treat the strokes drawn by the user on one hand as actual drawing elements, but at the same time as gestures. We feel that this makes it easy for the user to declare his/her intent, and also easy for DrawCAD to recognize the intent.

User studies are presented in which some benchmark drawings are created using DrawCAD as well as standard programs. Some of our benchmarks are simple informal drawings, and others are detailed engineering drawings with dimensions etc. Our general conclusion is that DrawCAD is very robust, easy to learn, and fast to use.