## Thursday, October 27, 2016

### Grids and Coordinate Planes

The other day I watched one of those police shows where they created a grid of people to walk through an area, hoping to find the body of a missing person.  This reminded me that grids are used in real life.

We see grids used all the time but we don't always think about its uses. Although this is not true of my local phone book, many phones books for larger cities include pages of maps set up with a grid overlay.  Usually one axis is labeled with letters while the other uses numbers so the store you are looking for might be in section A-3.

Archeologists and geologists tend to divide the land up into grids so when they find something or make an observation, they can make note of it through a coordinate system.  Landscapers plan using a coordinate system because they have to know where the house, garage, and other buildings are before deciding the location of all the plants and trees.

Even digital photographs and screens are created using pixels which are another way of saying coordinates for each unit.  You hear the resolution might be 1290 by 780 pixels which means you have an x and y location for every single pixel in the picture.  The same idea works for video games and where everything is located.

Back to mapping.  All maps tend to have some sort of grid associated with them in the form of longitude and latitude.  For instance there are certain parts of Utah, especially places around Salt Lake City, use a grid system established in the mid 1800's when the temple in Salt Lake City was designated as the origin.  Most unincorporated places around the city assign addresses based on this grid system which uses North, South, East, or West instead of the X and Y axis.

In addition, there is the military grid reference system or MGRS, a geocordinate system used by NATO to locate places on earth.  The location is given using an alphanumeric string.  This system is derived from the Universal Transverse Mercator coordinate system.  It is said the United States  National Grid system is easier to read since the coordinates are written with spaces so the coordinates are easier to read.

Don't forget that search and rescue often divides their searches up into regions or grids to improve the chances of finding people.  With the availability of GPS, it is becoming more and more common to use that to help establish the search territories.

So much and I've only touched on a few areas grids are used in.  Maybe I'll be back to explore this topic.