Map load is a property quantifying the amount of map content. It indicates the level of map complexity and is important characteristics for map generalisation. To find a piece of information in a map quickly has always been an important issue of cartography, especially in crisis management and military mapping. However, to keep a map easy-to-read is essential also in maps for schools. The optimal level of map load, therefore, may differ according to the map aim, user skills, knowledge and surrounding conditions.
Map load is mostly classified to two subtypes: graphic (sometimes called visual, quantifying the amount of the graphic content) and intellectual (also called information map load, quantifying the amount of information or information gain). However, definitions and approaches to map load differ significantly between researchers. In practice, balancing the map load often remains on a subjective decision of a cartographer. And that’s what I am trying to change, providing a tool which can help cartographers to evaluate and compare graphic map load value of created maps …
Graphic Map Load Measuring Tool (GMLMT) is available for download under the licence CC BY-SA. The tool is a Python script for open-source graphic editor GIMP. After putting the file into the extensions folder of GIMP, you can find the tool in the menu Filty → Detekce hran.
GMLMT is suitable for all raster representations of a map in RGB (RGBA) colour space. To provide comparable results, the original map dimensions and 100 DPI image resolution are recommended. GMLMT measures graphic map load of the whole map or of a user-selected extent defined by GIMP built-in tools.
The tool was first presented at the EuroCarto 2020 conference for graphic map load comparison of school atlases.
User manual – detailed instructions for installing and measuring using GMLMT
GMLMT 1.3 (build 210401) – improvements in visualisation grid calculation and labelling
GMLMT 1.2 (build 210112) – export of a report into a text file (in Users folder), minor code upgrades
GMLMT 1.1 (build 201125) – regular grid for visualisation of map load distribution
GMLMT 1.0 (build 200709) – first official release