Paths and distance functions on three-dimensional digitized pictures. - Naoki Okabe; Jun-ichiro Toriwaki; Teruo Fukumura (Pattern Recognit. Lett., 1983)

The Pulse Extension Method for the Variable Neighborhood Distance Transformation of 2- and 3-Dimensional Digitized Pictures. - Naoki Okabe; Jun-ichiro Toriwaki (Syst. Comput. Jpn., 1990)

Extraction of contour lines by identification of neighbor relationships on a voronoi line graph. - Norio Mizutani; Toyohide Watanabe; Yuuji Yoshida; Naoki Okabe (Syst. Comput. Jpn., 1993)