coordinate systemmgrs
Given an MGRS grid reference, for example 4QFJ123678 (100m precision), is there a good way to obtain the adjacent squares (north, south, east and west) from that origin square?
Is it better to compute the neighbors within the MGRS system, or convert to lat/long, find the coordinates 100m away in each direction, and convert back to MGRS?
There's almost certainly a more elegant way to do this.
After you generate the grid of points, add the lat/lon (or UTM) values to the attribute table. Then use the Convert Coordinate Notation tool to generate the MGRS strings and use them to label the grid.
You can use proj.4 (which is working in the background for qgis), the transverse mercator projection and set the origin to your reference point (..here latitude 52 degree and longitude 11 degree).
proj +ellps=WGS84 +proj=tmerc +lat_0=52 +lon_0=11 +k=1 +x_0=0 +y_0=0
11 52
0.00 0.00
11.0001 52.0001
6.87 11.13
...
If you define a new coordinate system via the menu settings -> custom crs and apply an adapted proj.4 string for your task (modify the longitude and latitude), you can use it in qgis.
Best Answer
I believe that you cannot rely on computing adjacent MGRS grid references by altering the numeric values. I'm pretty sure that method works for going North and South but West or East is a problem because not all grid squares are 100,000km wide 30U YC 051 804 has an easterly neighbour of 31U BT 804 948 for instance, instead of the computable 30U YC 052 804. It is possible that even the method of moving a search point by a set distance may fail to return the adjacent grid square if the set distance is greater than the width of an adjacent grid square. I have a requirement for a system that allocates a location with a grid square identifier and then is able to find all such locations within a radius. I was hoping to do an initial coarse grain search for locations by getting all the grid square identifiers intersecting the area. Am not sure now if mgrs is the system to use due to this problem.