The scale of a map represents the proportion between the size of terrain elements and the size of those elements on the map.
As an example, a scale of 1:15000 means that the map represents the terrain reduced 15000 times. Thus, 1 cm on the map corresponds to 15000 cm on the ground, that is, 150 meters.
For Foot Orienteering, map scales vary depending on the profile of the event and the age group of athletes.
Forest maps have been regulated since 1969 by the ISOM document (International Specification for Orienteering Maps), which from 1982 defined that forest maps must be produced at a scale of 1:15000, except for masters and young people who use 1:10000 (map enlarged 150%). Currently the exception to this are middle distance races where the base scale is 1:10000.
Sprint maps, usually park areas and/or urban spaces, have their own specification (ISSprOM) and normally use scales of 1:4000 or 3000.
International Specification for MTB Orienteering Maps (ISMTBOM) defines that the base scale for a MTB orienteering map is 1:15000. The base scale for a MTB sprint orienteering map for a competition in urban areas is 1:5000.
For older age groups where reading fine lines and small symbols may cause problems due to deteriorating vision, enlarged maps are recommended for all formats.
For the youngest age groups where the capacity of reading complex maps is not fully developed, enlargement is always recommended.
If the map is enlarged to 1:7500 to improve readability for older and/or younger riders the map symbols may be enlarged 2.0× instead of 1.5×.
Contour interval is the vertical distance between each contour line.
The contour interval of a map is usually given in conjunction with its scale. For example: “Scale 1:10000 with contour interval of 2.5 meters”.
Different contour intervals shall not be used on the same map.
ISOM defines that the contour interval for Foot Orienteering maps is 5 meters.
However, on terrain with little difference in level where the slope is never greater than 5% and where the contour lines are separated by more than 7 mm on the map, a contour interval of 2.5 meters can be used.
The ability to easily assess the landforms is vital in MTBO. It is therefore very important that the contour interval for MTB orienteering maps is standardised.
The ISMTBOM defines that contour interval for MTBO maps is 5 m.
In very hilly terrain an interval of 10 m may be used.
In flat terrain where the slope all over the area is less than 5% or the contours would be more than 7 mm apart on the map, 2.5 m may be used.