The point location problem on the example of determining map identification number and map sheet extent in the IMW system

The point location problem is one of the most fundamental topics in computational geometry. This problem is particularly well illustrated in the context of maps. In order to determine a point location, it is necessary to work in a specified space, with known division rules. A practical example can be a map sheet division system adopted for the International Map of the World. Given the current advancements in spatial data acquisition and growing availability of spatial data sets, it has become necessary to design an algorithm to identify a map sheet corresponding to a selected point. Available digital data, e.g. orthophotomaps or LiDAR-based data sets, cover whole countries. Due to the size of such data sets, they need to be divided into smaller chunks. The article presents a method of determining a map sheet identification number and a map sheet extent based on the latitude and longitude of a selected point. An inverse problem has also been addressed, allowing a map sheet extent to be identified based on a map sheet identification number. The algorithms developed might be directly implemented in GIS software. They are presented in a ready-to-implement form in the Basic programming language with the use of basic data structures.