An orienteering map is a map specially prepared for use in orienteering events. It is a large-scale topographic map with extra markings to help the participant navigate through the course.
These maps are much more detailed than general-purpose topographic maps, and incorporate a standard symbology that is designed to be useful to anyone, regardless of native language. In addition to indicating the topography of the terrain with contour lines, orienteering maps also show forest density, water features, clearings, trails and roads, earthen banks and rock walls, ditches, wells and pits, fences and power lines, buildings, boulders, and other features of the terrain. Orienteering maps are 1:15 000 or 1:10 000 scale.
The International Orienteering Federation (IOF) publishes the standard for orienteering maps, including: ISOM (International Specification for Orienteering Maps), used for FootO forest maps. ISSOM (International Specification for Sprint Orienteering Maps), used for FootO sprint and TrailO maps. ISSkiOM (International Specification for Ski Orienteering Maps), used for SkiO maps. ISMTBOM (International Specification for Mountain Bike Orienteering Maps), used for MTBO maps.
Purpose
An orienteering map, and a compass, are the primary aids for the competitor to complete an orienteering course of control points as quickly as possible. A map that is reliable and accurate is essential so that a course can be provided which will test the navigational skills of the competitor. The map also needs to be relevant to the needs of the competitor showing the terrain in neither too much nor too little detail.
Because the competition must test the navigational skills of the competitor, areas are sought which have a terrain that is rich in usable features. In addition, the area should be attractive and interesting. Notable examples in the US include Pawtuckaway State Park, New Hampshire and Valles Caldera, New Mexico, both having many boulders and boulder fields, and a wide variety of other terrain types.
Orienteering maps are produced by local orienteering clubs and are a valuable resource for the club. Orienteering maps are expensive to produce and the principal costs are: the fieldwork, drawing (cartography), and printing. Each of these can use up valuable resources of a club, be it in manpower or financial costs. Established clubs with good resources e.g. maps and manpower are usually able to host more events.
History
In the early days of orienteering, competitors used whatever maps were available; these were typically topographic maps from the national mapping agency. While national mapping agencies update their topographic maps on a regular basis, they are usually not sufficiently up to date for orienteering purposes. Gradually, specially drawn maps have been provided to meet the specific requirements of orienteering.
Maps produced specifically for orienteering show a more detailed and up-to-date description of terrain features. For example, large rocks above the soil surface do not normally appear on topographic maps but can be important features on many orienteering maps. New features such as fence lines can be important navigational aids and may also affect route choice. Orienteering maps include these new features.
Cartographer Jan Martin Larsen was a pioneer in the development of the specialized orienteering map.
Map content
The map scale depends on the purpose of the competition and also the standard used, for example, a map used in a foot orienteering long distance event has a scale of 1:15000. The map is printed in six base colours, which cover the main groups: Land forms, rock and boulders, water and marsh, vegetation, and man-made features, and an extra colour for overprinting symbols.
Brown: Land forms
Land forms are shown using contour lines. The contour interval is normally 5 metres, but other interval such as 2 or 2.5 metres may be used in sprint maps. Additional symbols are provided to show e.g. earth bank, knoll, depression, small depression, pit, broken ground etc.
Black: Rock features
This group covers cliffs, boulders, boulder fields, and boulder clusters etc.
Blue: Water features
This group covers lakes, ponds, rivers, water channels, marshes, and wells etc.
Green/Yellow: Vegetation
This group covers vegetation. White is typically open runnable forest. Green means a forest of low visibility with reduced running speed, being graded from slow running, through difficult running, to impassable. Yellow colour shows open areas. Green vertical stripes are used to indicate undergrowth (slow or difficult running) but otherwise with good visibility.