This is more of a how-to guide than an article, per se, but I hope you find it interesting nevertheless.
If you want to get the general idea of an area, you go on Google Earth and spin the location around. If you want to really understand a place, you purchase a map and study it. If you want to know the furthest corner of the globe like the back of your hand… you make a map of it. It might seem that producing one’s own map of an area that Google Earth and countless stores have already covered, but there’s no better way to learn about an area than to graph it. At the least, you can always map fictional places.
(Quick note: if you’d like to see some of the maps I’ve made using the following technique, try visiting the “maps” section of Schreiben Depot if you haven’t already. http://schreibendepot.blogspot.com/search/label/Maps )
This guide is meant to help you produce a high-quality map with geographic coordinates (longitude and latitude) for grids. It might not eclipse the store-bought variety, but you’ll learn enough from the experience to make it worthwhile.
Because the information provided can be a little hard to follow on its own, I’m going to include examples of what I’m talking about with important steps. Hopefully, this will assist you on your own coordinate mapping adventure.
Let’s begin! All you need right now is the computer you’re currently staring at.
Step 1: Open up Google Earth. The program is an all-but-vital part of the process; please download it if you haven’t already.
Step 2: Using Google Earth, locate the area you wish to map on the screen. This could be a city, a county–anything of your choice, though this specific kind of map works best for an area 500 x 500 yards or larger.
Example (see picture): I’ve decided to map a small section in Northwest Washington, D.C.
Step 3: Before you can draw in the map, you’ll want to plot out your coordinate grid. (For clarity purposes, let’s assume that your grid will be composed of inch-by-inch boxes. Any value works just as well as the next, but you may want to try out a map with inch-long spacing in between lines as an introduction to the process.) Using Google Earth’s line/path tool, draw a line from the eastern edge of the area you wish to map to the western edge. Find the distance, in yards, then divide by 24.6. This is ROUGHLY how many east/west (latitudinal) seconds your map will contain. Do the same measurement (in yards) going from the northernmost to the southernmost portion on the map, then divide by 33.7. This is the rough total for how many north/south (longitudinal) seconds your map will contain.
Example (seen in picture): my area measures 827 yards E/W by 810 yards N/S. Divided by 24.6 and 33.7, respectively, it looks like my map will take up APPROXIMATELY 35 E/W seconds and 30 N/S seconds.
Step 4: Stand up, breathe deeply in, then breathe deeply out. You’ve got a few tough steps in front of you.
Step 5: This is going to take a little guesswork on your part. With the length (in seconds) of the east/west and north/south dimensions of your mapping area, and keeping in mind the size of your mapping medium, calculate how many seconds per inch your map will have. Anywhere from five seconds per inch and less is usually enough to map out streets and buildings in cities, though 10 seconds per inch also works well for a less detailed map.
Example (seen in picture): I’ll be using an 8.5/11 sheet of letter paper for this map. It looks as if a 5 second-per-inch relief will work well here; at 35 x 30 seconds (see my example above), that’s a 7 x 6 inch map. This gives me space to put in coordinates and other information in the margins.
Step 6. It’s finally time to plot out your grid! Put down your calculator and open up Google Earth once again. Go to the northwest corner of your mapping area and, using the coordinates on the bottom left of the screen as a guide, move around your cursor until you find a spot whose north/south and east/west coordinates are exactly X.00 seconds. (For example: if my relief scale was five seconds an inch, a good place for the northwest corner of my map might be XX XX’ 50.00″ N, XX XX’ 35.00 W. This step is not vital, but it can make your map much easier to follow. Then, progress however many seconds east and south your dimensions called to reach your southeast point. It, too should be rounded to a convenient coordinate.
Example *see picture): it looks like the best Northwest corner on which to start my map is 38 53′ 55″ N and 77 01’25” W. Going 35 seconds east and 30 seconds south, I get to 38 55’25” N and 77 00’55” W.
Step 7: These are the first two corners of your map. Now, use a little common sense to fill in the other two.
Example: Based on my NW and SE points, it looks like my map’s SW corner will be 38 53’25” N and 77 01’25” W; my NE corner, 38 53’55″N and 77 00’55 W.
Step 8: It gets easier from here–I promise! This is when we begin to start DRAWING the map on your paper. Pick a spot close to the top left corner–but not on the corner–to start. Put a dot here; this will be your NW point. Then, keeping your seconds-per-inch value in mind, go however many inches east and south you need to get to your NE and SW corners, and plot those points, too. (You’ll want to use a ruler for the lines, unless you’re one of those people with an anti-ruler streak.) As you go, make marks every inch. Once you have your NE and SW corners, go ahead and draw horizontal and vertical lines from those inch-apart marks to the opposite side of the page. Congratulations! You’ve just gridded a series of geographic points.
Example (see picture): From my NW point, I go seven inches (35 seconds at 5 seconds-per-inch) right, or east, and six inches (30 seconds) south. This gets me to my NE and SW points, respectively. Having made marks every inch, I now draw lines from those marks to the opposite side of the page to form my grid of 30 boxes, each 5 seconds by 5 seconds. My SE corner is the last point gridded.
Step 9: Label your points! You don’t need to give the coordinates for the corner of every box in your grid, nor do you need to write out the full geographic points.
Example (see above picture): I’ll just give you the coordinates I write going from the NW to the NE corner, with one number every mark: 77 01’25” W, 20″W, 15″W, 10″W, 5″W, 0″W, 77 00′ 55″W. Notice that I only bothered giving out the full latitudinal coordinates for the leftmost and rightmost marks.
Step 10: This is both the longest and the easiest step at the same time: fill in your map! Outline the major streets/features in pencil first, then lay out the rest of the area around it. (To avoid confusion, I would trace over your latitudinal/longitudinal grid lines with colored pencil to separate them from the streets.) The level of detail and the number of features you represent in the map are up to you. I HIGHLY advise using ink and color at the end to make your relief easier to read.
Step 11: At this point, you have a working geographic map of the area. All done, right? It’s your choice. You can either head out right now and test out your design, or you can stick around for a few more steps and make your map especially useful.
Step 12: Take out a new piece of paper and re-draw the grid you made earlier. (It should be easier now without the math, and you need not use a ruler.) What’s the point of this new grid? This serves as a nifty way to keep track of important buildings, intersections and natural features that fall within your map.
Step 13: Go back to Google Earth and look around for things worth jotting down the coordinates of. Write the item and its coordinates within the box in your grid that the item falls within. (Confused? I would be. See my example.)
Example: Back to my map. It just so happens that Washington’s National Police Memorial (dedicated to cops who pass away while on duty) lies within my map. Its coordinates are, to the nearest second, 38 53’48 N and 77 01’03” W. I now grab my new, blank grid and jot down “Police Memorial- 48N, 03W” in the box 5 to the right and 1 down from the northwest one. (Why this box? Within it lie the coordinates for the Memorial.)
Picture at right: This was my finished map for the “Eastern Core,” as I called this area. I looked online, found the geographic coordinate for some “points of interest” and plotted them on the face of the map. (You can do this pretty easily by using an Excel scatterplot for points and latitude/longitude for your axes, though it can get tricky with the margins. I won’t go into that right now.) Anyway, this is just an example of how you can find and plot points onto your map.
Step 14: It’s time to go and visit! Take a trip over to the area you just mapped, walk around and look for new points of interest to include in your coordinates section. Part of the fun of making your map is the chance to venture into an unknown territory and begin exploring the area—just like the explorers of old did some 500 years ago. You might not be the next Magellan, but at least you have a place to record the findings of your quest.
Step 15: If you really want to get fancy with your map, laminate the first grid (the one on which you drew out all the streets, buildings and features) and tape the second grid (the one with the coordinates of all the buildings) to it. You might even staple two adjourning maps together if you end up making more than one. Experiment with folding the second grid behind the first one, then attaching a tab so that you can pull it out when needed.
I hope this guide was easy enough to follow. Pictures that go along with the instructions would definitely help; hopefully, I’ll put some up soon.