Collecting Existing Maps

Gather all you can find on the area; topo maps, aerial photographs, park maps, old orienteering maps, engineering blueprints, landscape drawings or site plans. Most states have a Department of Natural Resources that may have useful map data. Many county governments are putting their tax assessor's office online with property boundaries and recent aerial photographs.  

Select a Common Scale

Orienteering maps are typically 1:10,000 or 1:15,000, however other scales may be used for special projects like Park-O or Bike-O. Whatever scale you choose, you'll need to convert the maps you've collected to that scale so you're comparing apples to apples -- not oranges. The height-to-width ratio all the images should be about 1.3 or 1.5, which is the same as a 8.5x11 or a 11x17 page. A good program for manipulating image files is IRFANview, available at www.IRFANview.com .

Sources

Here are sources for maps along with some recommendations.

Topo Maps

Get a topo map from www.topozone.com and start from there. Be sure to copy the linear scale along with the topo map. In your browser (MSIE), hit <F11> for full screen mode. Scroll until you have the desired area with the scale on the screen. Use <ALT><PrtScrn> to copy the screen, then in IRFANview use <CTR>-V to make a new BMP image.  

GPS (Global Positioning System)

Good mappers can make good maps without the use of battery-powered gadgets. However if you choose to use a GPS to help pin point coordinates, consider the following advise: 

Hardware Requirements

1. Your GPS must have a port to download track data from the GPS to your computer. 

2. Your GPS MUST be used with an external antenna, because your body will block satellite reception from behind you. An external antenna mounted at head height will receive satellite data from a complete 360-degree view. This improvement is significant. 

3. You'll need a good quality 12-channel receiver. Some new models have WAAS capability, which might be helpful to the mapper. The Garmin GPSmap76s has received favorable reviews from o-mappers.   

Accuracy

You must be aware of the many situations in which a GPS may not record data with adequate accuracy for map making.  

-  Cloud cover will absorb and reflect satellite signals
-  Leaf cover will block the view of the satellites.  
-  At any one time, satellites may be positioned poorly for optimum reception.  

To judge the accuracy of your GPS, follow a trail up and back to your start. The two track plots should follow each other precisely. If successive recordings of a trail do not match very closely, do not use the GPS data on your map. In many situations, traditional methods (compass bearings and pacing) may be more accurate than GPS data.

Setup

1. Be sure the receiver has fresh batteries.

2. Check that any "power saver" feature is turned OFF!

3. Set the tracking options to collect track data as often as possible.

4. Be sure to use the correct datum setting. Your GPS should use the same map datum as your base map; this may be WGS-84 or NAD-27.

5. Setting the instrument to use UTM (Universal Transverse Mercator) coordinates may help you estimate distance and position in the field. The UTM system reports locations as distances north and east from an origin. See a complete explanation at: www.maptools.com/UsingUTM

6. To make a template for OCAD, download track data from the receiver and plot it. This is not an OCAD function. Instead, use a program called "Waypoint+" to plot your data, available at http://www.tapr.org/~kh2z/Waypoint. You can plot it on a map or just as a pattern of dots and lines. Save the plot as a BMP image, and open this image in OCAD. There is a GPS button in OCAD under the "Options" menu, but this is not the best way to use GPS data.

Geographical Information Systems (GIS)

There are various GIS systems and data that may be useful for the o-mapper. These are options, not requirements, for making a base map. DEM data files can be used to make contours lines. A program called MicroDEM is useful for this purpose. This is free software developed for use by the Navy. See the procedure in appendix one for instructions. The DEM contours are, at best, an estimation. You will have to make corrections and enhancements.

Internet Resources

The GEO Community  
http://data.geocomm.com/catalog/US/61089/sublist.html

Terraserver  
http://terraserver.homeadvisor.msn.com

TopoZone  
http://www.topozone.com

Georgia GIS Clearinghouse  
http://gis1.state.ga.us/orthoview.htm

South Carolina GIS Clearinghouse  
http://www.dnr.state.sc.us/gisdata/index.html

Links to help and Advice

The International Specification for Orienteering Maps ISOM
http://lazarus.elte.hu/tajfutas/isom2000/index.html

Jim Huggins' mapper help  
http://www.softdisk.com/customer/jimh/map101.htm

Tony Federer's mapping help 
http://www.nh.ultranet.com/~compassb/mapproc.htm

Chuckonut Orienteering - Guide to field mapping 
http://www.televar.com/~maryse/fieldmapping.htm

The Parkland Mapping Manual is a good resource: 
http://www.orienteering.asn.au/Mapping/index.html