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Posts Tagged ‘information’

In Monday’s post I talked about the North Coast Geotourism form through which you can submit locations of interest; on Tuesday I mentioned that the only tricky part of the form was getting the latitude and longitude coordinates, and on Tuesday I explained how to do this online.

If you want some background on what latitude and longitude mean, read on. You don’t need any of what follows in order to locate the coordinates of a point — only to understand what these coordinates mean; but if you are interested in the background, this is for you.

They are those lines you see drawn on maps and globes. Imagine the Earth has been sliced in wedges like an orange, from its North Pole to its South Pole; each cut would represent a meridian. The imaginary “slice” line on which the Greenwich observatory sits, in England, is by international convention the prime meridian, our “zero” meridian.

Next, imagine that the Earth is also sliced in the other direction, but in parallel slices instead of wedges, in lines that cut slices of even thickness from North to South. Each line is called, aptly enough, a parallel. The line going through the Equator, at the exact same distance from both poles and where the Earth’s girt is thickest, is the “zero”. You can see a picture map of the results here, with the Earth semi-unwrapped and flattened.

When we talk about the latitude of a point, we mean its distance, North or South, from the Equator, with 90 degrees between the Equator and each pole; which is the same as asking which parallel it is located on. A point located at exactly 45 degrees North is halfway between the Equator and the North Pole. Every point with the same latitude is on the same parallel circling the globe.

And when we talk about the longitude of a point, we mean its distance from the prime meridian, measured east or west from 0° (along the Greenwich meridian) to 180° (on the other side of the world from the Greenwich meridian). In other words, we’re talking about which meridian the point is located on.

With these two measurements, we can describe to location of any point on the surface of the globe. Why don’t we have the same “shape” for the lines encircling the globe in both directions (north to south, east to west)? Because there is a north pole and a south pole thanks to our planet’s rotation on its axis; but there is no east pole or west pole because the earth doesn’t spin in a second direction. The north-south axis represents a “real” line, something concrete if intangible.

Links of interest:

  • The Geographic Grid by Dr. Christine M. Rodrigue, California State University — Long Beach (CSULB)
  • Navigation — a chapter of the Pilot’s Handbook of Aeronautical Knowledge

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Some people find it daunting to orient themselves using a map. If you’re not used to this way of seeing the world, or to reading the symbols, it can be confusing at first. But I learned to read maps as a kid, to pass the time in the backseat of the family car when we went on vacation, so if a nine-year-old can, you can too.

What follows in this article is the step-by-step overview of how to find a spot on the map without an address.

Finding a location

Maps are two-dimensional representations of human and physical space that are packed with information; don’t try to take all this info at once. Instead, try orienting yourself in pretty much the same way you do in real life: start with a landmark you can easily recognize.

I like to start with a major road because they’re so well labelled. Once you’ve found a big road that goes somewhere in the vicinity or general direction of your site, find a second landmark that the road crosses; for example, a town, a major cross-street, etc. For all landmarks, pick ones whose position in relationship to your target site you understand well.

Now that you have these two helping points or lines to figure out where you are, follow the road as if you were walking or driving to your target site. Pay attention to cross-streets, and trace your steps back (or start over from the beginning) if you get lost.

For example, let’s say we want to go the beach near Orick, north of Redwood Creek, and we’re using Google Maps (or one of the applications based on it, like iTouchMap.com) to find the spot. First, let’s move the map around until California is roughly in the center of the map, and click on the “+” end of the scale bar to the left in order to zoom in. (Or, if your mouse has a scrolling wheel, position your cursor over the point you want to zoom on and scroll “up” to zoom in, “down” to zoom out.) We have to do this a few times, recentering on Northern California until we start seeing features we can recognize.

The first landmarks will be big name places like San Francisco and Portland. We know we’re in between, so we’ll zoom until we see Eureka appear, then Crescent City. We soon see U.S. 101 running up the coast, which helps us get situated.

We continue to focus progressively closer until we start seeing more place names we recognize — Arcata, McKinleyville, Trinidad, Klamath — and position our next zoom as close as we can north or south of those known locations. At last, we see Orick’s name appear and we can focus on that area.

If we were using a paper map, we would also start with something recognizable like U.S. 101 and start looking north from Eureka, or south from Crescent City, along the road until we saw more familiar place names. Say we’re moving north from Eureka, following U.S. 101. Even if we miss Orick, once we see Klamath or Crescent City, we know we’ve gone too far and need to trace our path back along the road until we spot Orick.

Either way, we see Orick there in the little bend U.S. 101 makes, just north of Freshwater Lagoon and before crossing the swath of Redwood National and State Parks that encompasses Prairie Creek. If we’re using a paper map, we may be limited in how much detail we can see, but with on-line mapping we have the luxury of great detail. We can continue to zoom on the Orick area until it starts filling the map. As we zoom, we notice that new levels of details, such as roads, appear only at certain zoom levels.

Now, from going there before, we remember (for example) that the beach access we were thinking of was on the north side of Redwood Creek. So we’ll get close and follow U.S. 101 until it crosses the creek, then take the first side road that heads west toward the coast; that’s Hufford Road. We might have to do this a few times if we pick the wrong road, but this time it will work. We keep following Hufford Road, a very small road that becomes a dirt track, until we reach the beach.

And in Google Maps, or iTouchMap or Google Earth, we can click to put a marker there. In iTouchMap, we can see the point’s longitude and latitude by clicking on the point or by scrolling down below the map. Voilà, we’ve located a geographic feature without having an address.

Map symbols

All maps use symbols to represent information about the geography they cover. For example, maps usually show cities and towns with dots of different sizes corresponding to their population, and roads with different widths and colours depending on their importance, paving, and number of lanes.

Maps may also use symbols to indicate all sorts of information, such as the presence of tourist attractions (golf course, lookout points, vistas, rest areas, supervised beaches, campgrounds, etc.); emergency facilities (hospitals, police stations, fire stations, etc.); other man-made features (railroads, dams, churches, mines, etc.); natural features and ground cover (rivers, ponds, wetlands, forested areas, etc.); and terrain (especially through the use of contour lines, hatching, and shading).

Paper maps sport a “legend“, that is, a list of all the symbols used and their meaning, usually in a corner. Here are a couple of sites showing the symbols used on topographic maps from the U.S. Geological Survey (USGS) and Natural Resources Canada. Topo maps are some of the more densely packed with information.

Online mapping applications may not display a legend because they can allow the viewer to click on features in order to identify them. They also offer another way to convey information to the user: most offer choices of different views of the area covered.

For example, Google Maps and its derivatives offer a choice between the “Map” view (a graphical representation of the area), the “Satellite” view (photo representation), a “Hybrid” view (aerial photos with roads and symbols superimposed), and “Terrain” (a graphical representation that uses contour lines and shading to represent the three-dimensional shape of the terrain surface).  Note that each of these view is only available at certain levels of zooming.  (In both images I showed above, I used the Hybrid view.)

You can switch back and forth between views; some people find aerial photographs easier to understand because they show the world in true (or truer) colours, while other people find them confusing because they may show more detail than the viewer wants.

Coming up: What are latitude and longitude?

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binary1You know you ought to keep backups of key information on your computer, and you’re probably pretty good about it.  But if you’re like me, you may forget to backup your online information.

After having been burned on this before, I periodically backup my address book and my bookmarks.  Thanks to a couple of reminders some time ago, I now remember to periodically make copies of my LinkedIn and JibberJobber contacts as well (and sync them with my Outlook address book at the same time).

But you know what I never, ever thought to backup?  My blog files!  Somehow, I’ve entirely forgotten to keep safety copies of files that are kept online.  This was highlighted today because LiveJournal has just laid off 12 of its 28 employees, reportedly without severance.  The LJ community is in a tizzy as this is seen as a sign that the site may go belly up.  A friend suggested that those who use LJ should backup their entries promptly, which I did.  And in the process, I realized that I should also backup my WordPress entries!

So it’s not a particularly novel idea to have a set day of the week or month to refresh files, but I will now add my blog entries to the list of files to update.  What else should I be updating that I’m forgetting right now?

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