A Computational Procedure for Making Seamless Map Sheets

Map sheets are often used as basic spatial units for managing spatial data produced from paper maps. This often results in incompatibility between adjacent map sheets spatial objects do not cross the boundaries smoothly and even the boundaries themselves do not match their neighbors exactly. To solve the problem this paper proposes a computational procedure for making seamless map sheets. Line objects digitized separately in different map sheets are considered, which are frequently used to represent road networks, gas pipelines, and boundaries of polygon objects. The procedure consists of three steps: 1) extraction of end nodes, 2) detection of matching nodes, and 3) transformation of the map sheet. Each step goes interactively so that unexpected errors can be avoided by human observation. To test the validity of the procedure, map sheets are combined containing the road network data of Tokyo 23-ku area, Japan.