Summer 2017
Identify surfaces by finding loops. Identify cuboids by finding connected surfaces.

Interpreting Line Drawings
Tyler Nowicki
University of Waterloo
September 17, 2015

This is a presentation on a method I developed to identify multiple cuboids in a line drawing. This method treats the line intersections as a graph stored in an adjacency list. Loops in the adjacency list indicate potential surfaces. Loops with two sets of parallel-ish edges are treated as surfaces. Three adjacent surfaces that meet at an intersection determine a cuboid. Construction of the 3D cuboids is accomplished by a least squares fit to the intersections of the suspected cuboid drawing. Partially occluded surfaces are identified by labeling the edges of foreground cuboids. This method is able to identify and construct cuboids even when lines or intersections are occluded, but not whole surfaces. The least squares identifies a cuboid for most cube-like shapes. However, the method is limited to cuboids only. Generalizing the method to other shapes would be difficult because the variety of intersections and their interpretation increases greatly with additional shapes.

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