Resection

Resection


Resection (also called 'back bearings' or 'cross bearings'), is a technique by which you can calculate your location based known land features on the map

Resection 

Resection


Resection is a technique by which you can calculate your location, base on known land features on a map.

The technique relies on having two (intersection), preferably three (triangulation), known land features that you can identify on the map, against which you take a bearing, then plot the bearing on your map so that you can calculate you exact position on the ground. 

However, oftentimes when you need to calculate your position, the visibility is such that you cannot see much at all, or the landscape is so featureless (e.g. open moorland) that there are no, or too few, features it identify on land and map for the process to work.

Resection can also be time consuming unless practiced, and depending upon your map set-up, you may not have sufficient visible map area to identify on the map any prominent features that you can see on the landscape. For this reason, you could carrying an large map case – thus displaying more map area.

An additional problem with this technique will occur if your compass base plate is too short. You could always take a ruler...

Example Resection

This example uses three land to map bearings, referred to as triangulation, which is more accurate than just two bearings. The principle for using only two bearings is exactly the same.