OCAD

OCAD is software for drawing orienteering maps.

Rarely does creation of an orienteering map need to start from scratch with field work. One or more existing maps (background maps) can be used as sources. Possum Trot Orienteering Club (of Kansas City) has an outline of the steps involved[1] and an online tutorial.[2]

In OCAD 10, creating a new orienteering map can be greatly simplified if you start with a georeferenced background map, and you know the current magnetic declination of the location.

## Using background maps

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OCAD supports the use of multiple background maps. Each background map is treated as a separate layer. If georeferenced background maps are imported, OCAD will align them to each other automatically. Else, you will need to align each new background map to the previous map(s) by hand.

Background maps are not copied into the OCAD map file (file type .ocd). This means that if the map file is to be given to someone else to work on it, the background map files need to be given too.

## Declination adjustment

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All orienteering maps are oriented to magnetic north. However, many existing maps that are used as sources are oriented to true north or grid north. Thus, some adjustment may be necessary to adjust source map data so that it is oriented to magnetic north. You can ignore the difference between true north and grid north.

Because the earth's magnetic poles wander, if your source is an older map you may want to not rely on the declination printed on the map. Instead, look up the current declination adjustment for the location. A free online tool is provided by the NOAA Geophysical Data Center.[3] Even if the source map is oriented to magnetic north, you may need to look up the current declination and make an adjustment if magnetic north has changed more than 1 or 2 degrees since the map was made.

Declination adjustment can be done in OCAD.

## References

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1. ↑ http://www.ptoc.org/mapmaking_101/handouts.pdf
2. ↑ http://ptoc.org/ocad_101/
3. ↑ http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination