Recognition of Hand-Drawn Graphs Using Digital-Geometric Techniques

A novel algorithm to recognize hand-drawn graphs is proposed. The algorithm uses properties of digital-geometric straightness combined with a new idea of Farey sequence, followed by geometric refinement, in order to speed up the recognition of graph edges. In the next phase, the nodes of the graph — which, being hand-drawn, are very grossly circular — are recognized using the annular regions containing the vertices of their corresponding isothetic covers. Results of the two phases are finally compiled using interval search to output the adjacency list of the graph. The problems of jaggedness, waviness, and similar unforeseen aberrations usually present in a hand-drawn graph are well-tackled by the adopted techniques, as verified by our experimentation on various hand-drawn graphs. Some results have been given in this paper to show the usability and efficiency of the proposed algorithm.