Course planning symbols and their dimensions are defined for forest competition in ISOM2017-2 (International Specification for Orienteering Maps 2017), and for sprint competition in ISSprOM 2019 (International Specification for Sprint Orienteering Maps 2019). Both these documents are available from the IOF (International Orienteering Federation) website

Competition format

Start triangle

Control circle

Control number

Finish circles

Sprint (1:4 000)

7 mm sides

6 mm diameter

4 mm height

Concentric circles, diameters 5 mm and 7 mm

Forest (1:15 000)

6 mm sides

5 mm diameter

4 mm height

Concentric circles, diameters 4 mm and 7 mm

The important thing to note is that these dimensions are specified for the printed scales of 1:15 000 and 1:4 000. When enlarged (or reduced), the overprint symbols should be enlarged (reduced) proportionally. This requirement is more noticeable for forest orienteering maps where we occasionally have maps drawn at 1:15 000 printed at 1:10 000 and 1: 7 500 (and occasionally at 1:5 000), so a 1:15 000 map printed at 1:5 000 will have control circles with a 15 mm diameter, compared to a sprint map printed at 1:5 000, which will have control circles with only a slightly smaller diameter than sprint maps printed at 1:4 000.

The reason why the circles are enlarged (or occasionally reduced) is to maintain consistency with control descriptions. Older versions of the mapping specification prescribed a fixed size for control circles, so for detailed terrain, it was often necessary to have different control descriptions for the different scale maps as the area covered by a 5 mm circle at 1:15 000 is greater than that covered at 1:10 000 – strict enlargement eliminates this problem, however, where forest maps are printed at a scale of 1:5 000 for all competitors, there will be no inconsistency, so it is reasonable that the course overprint symbol sizes should be a size that doesn’t dominate the map, although the much preferred option is to stick with the standard scales for forest maps (1:15 000, 1:10 000, and for detailed maps for older age groups, 1:7 500). 

The course overprint symbols are generated by course planning software (in Tasmania we use Condes – currently version 10). The symbol sizes to be used are defined in the Canvas>Course Overprint Symbols and Dimensions menu. The symbol sizes for sprint maps don’t usually present a problem (unless printing at, say, 1: 1000), so the discussion will focus on forest maps. 


By default, for forest maps, the ISOM 2017 dimensions are selected (as defined in the ISOM 2017 specifications, hence they are not shown in the dimensions panel of the dialog box). If you really want to change the symbol sizes, select the Configure dimensions and symbols for this canvas radio button:


When this option is chosen, you can change the symbol sizes to whatever you want, but remember that the map symbol sizes (not the overprint symbols) will be increased (e.g. 3x for a 1:15 000 map printed at 1:5 000), so you should probably increase the leg and circle line widths to compensate for the increased line widths (e.g. contours and tracks) on the map itself.

Note that the map will be printed according to the settings you choose, so it is your responsibility to ensure that the map looks sensible! Don’t assume the person printing the maps will make changes to improve the presentation of the competition map. If you feel you must deviate from recommended practice and insist on printing forest maps at 1:5 000, either accept that the overprint will look silly, or experiment with overprint symbol sizes and line widths before sending the map off to the printer.

Greg Hawthorne,

Director, Technical Orienteering Tasmania