Map & Compass – How to Find Your Position on a Topo Map Using a GPS & UTM
This quick video shows you how you can use your GPS to find your position on a Topo map using the UTM / NAD 83 format & datum. There is a LOT to learn about map reading which is useful when your GPS fails.
Anybody with tips can post them as video replies or comments.
When using your GPS in conjunction with a topo map, is to make sure that Datum is the same on the GPS as on your map. For example, out of the box GPS receivers are set to WGS84 while most topo maps are probably NAD83. This is important to set since it will make a different where you are on the map.
The next setting to change is the position format. Depending on the age of the map, it will be using UTM number format instead of GPS friendly lat/log format. Position format is much like a phone number, you can write it in various ways, but they all mean the same thing.
Now you can take a set of coordinates from the GPS, either grab a waypoint, look up a phototagged image. Here we want to get the position where we are and where we want to go, like a visitor centre.
Write down the UTM coordinates on to a piece of paper. Take the corner of the piece of paper and mark out the scale, using UTM each tick on a grid is divisible by 10. So you can take each digit in a UTM and narrow down on the map by 100m in this example.