Implicit Geometric Constraint Detection in Freehand Sketches Using Relative Shape Histogram

Abstract

In order to take advantage of the sketch-based interaction, many methods have been proposed to beautify freehand sketches. Most of these efforts are dedicated to sketch segmentation and recognition, while some important information implied in the sketches, such as geometric constraints, are largely ignored. Thus, the final beautified results by these methods do not fully reflect the true intentions from users. In this paper, a statistical approach called Relative Shape Histogram (RSH) is introduced to detect the implied geometric constraint in sketches. The basic idea arises from such a discovery that the same geometric constraints between two geometric primitives have similar relative shape histograms. By computing the similarity between RSHs, the implicit geometric constraints between two segmented primitives are inferred. To evaluate the performance of the proposed algorithm, a userbased experiment is conducted and the results are presented in this paper.