YMP: Choosing Map Scale & Symbol Set

Size: For the purposes of OUSA’s Youth Mapping Project, a mapped area ideally fits on standard, Letter sized paper (8.5” x 11”), while allowing for adequate space for map layout, like map title or name, explanatory text, legend, branding, etc.

The scale should be appropriate for the project; typically ranging between 1:1,000 and 1:4,000. We strongly recommend reading the OCAD Wiki on map scale.

The symbol set is chosen as a function of the area to be mapped and the intended scale for the final printed map, with Magnetic North being at the top of the page, whether in Portrait or in Landscape page orientation.

Safety Bounding: When determining the area to be mapped, it is recommended for the edges of the mapped area to consist of major linear features (road, stream, ridge, etc). Significant features (large buildings, roads, towers, etc) just beyond the boundaries may be usefully shown. The mapper should adjust the area, depending on issues like suitability and safety, especially for younger students.

The area of the map will need to be measured to use in the mapper contract to determine payment and/or donation amount. To do this in OCAD or OOM, simply draw a polygon around the area to be mapped using an area symbol, then go to the measure tool to view the area measured. For YMP purposes, areas should be given in square kilometers. Also, it’s important to only measure the usable area of the map, in other words, the area to be field checked and where competitors will be allowed to go. So don’t include out of bound areas at the edge of the map and if there are large out of bounds areas in the middle of the mapped area, measure those separately and then subtract those areas from the total mapped area.

The primary data sources will often be publicly available Lidar data and aerial imagery. If Lidar data exists, but is not publicly available and possibly only for a fee, it is sometimes useful for the school or scout group to approach the local entity for acquiring the data from their county or local GIS office, as they would be the locally benefiting non-profit organization educating local youths, and may thus get the data at a reduced price or even for free. They may, though, need help in finding the data and formulating the proper inquiry to said office.

Included information: Every final map should include the required titles, explanatory text, branding and copyright information. Plan for adequate space available for map layout (explanatory text, logos, title, etc.). Communicate with the organization requesting the map whether it is desired for the legend to be on the map, or provided separately, and plan accordingly.

The two IOF symbol sets to choose from are the School Symbols Set, for scales 1:2,500 to 1,000 and even larger scale, and ISSprOM 2019, for scales 1:4,000 and 1:3,000.

Ideally all maps will be prepared using only the unmodified symbols described in the standards below and provided in these symbol sets. This enables international competitors, but also young children who can’t read yet the words in a legend, to receive a locally produced map and find it portrays the terrain in exactly the same way as in their home country or local club. It also enables local orienteers to become familiar with the mapping conventions that are used for major events elsewhere. The use of local symbol variations defeats the purpose of mapping standards and may confuse students who experienced orienteering in other places.

ISSprOM 2019

  • Scale: The map scale shall be 1:4,000. Enlargement to the scale 1:3,000 is always recommended for the youngest age groups where the capacity of reading complex maps is not fully developed.
  • Contour interval: The contour interval value shall normally be either 2 m or 2.5 m. But in some special cases of steep areas 5 m is allowed.
  • Dimensions of map symbols: No deviations from the given dimensions within these specifications are permitted. It is however accepted that due to limitations in printing technology the final map symbol dimensions may vary up to +/- 5%.

School Symbols Set

  • The IOF School Symbols Set for school and small park maps is for scales 1:1,000 to 1:2,500.
  • The basis for the symbol set is the ISSprOM 2019, with all ISSprOM 2019 symbols having been enlarged to 125%.
  • 6 additional symbols have been added to represent common school grounds and park features. This is to replace the multitude of school symbol sets that have been used until recently.
  • See examples of use in pictures on the OCAD School set website

In the table below, the Approximate Maximum Dimensions in the first column are the width x length in meters of the area to be mapped, assuming final “Portrait” layout on a Letter sized page (21.6 cm x 27.9 cm) — i.e., the E-W x N-S extension in meters.

Approx. max. dim.Final printed map scaleSymbol SetDistance between North Lines
200 x 2651:1,000School Symbols Set30 m
Various1:1000-1:2500School Symbols Set30-75 m
500 x 6601:2,500School Symbols Set75 m
600 x 7901:3,000ISSprOM 2019120 m
800 x 1,0501:4,000ISSprOM 2019120 m
1,000 x 1,3251:5,000ISSprOM 2019120 m

You may want to read the Map Scale OCAD Wiki for a better understanding on how to plan in what scale to draw, when to use enlarging by printing, how to use the program’s “Enlarge/Reduce” symbol, “Scale Change” or other scale-related functions.

Map naming: When starting with a map, one may already want to name the map file according to the YMP File Naming Convention

Return to YMP: Information for Mappers