Recently in Cartography Category

Fun with Google Earth
January 28, 2016 9:41 PM | Posted in: ,

One of the many cool features about Google Earth is the ability to step back in time to see how an aerial scene has changed. Beginning with Google Earth 5.0, introduced in 2009, "historical imagery" was integrated into the application. As far as I can tell, much of the imagery (dating back to around 1984) came from the USGS, but there are a lot of images which are dated well before that. The results are inconsistent, but here are a few of the oldest images for some well-known cities:

  • San Francisco - 1938
  • Las Vegas - 1950
  • Los Angeles - 1989
  • NYC - 1978
  • Dallas - 1995
  • Miami - 1994
  • London - 1940
  • Berlin - 1943
  • Linwood, Ontario, Canada - 1930
OK, so Linwood, Ontario, probably isn't that well-known, unless you happen to live there, but by all accounts the aerial photo from 1930 is the oldest one in Google Earth. So, there's some fodder for your next family trivia night.

I was curious about what the historical imagery would show for our neighborhood and the immediate surroundings. Our development is only about ten years old, built in what was previously open pasture, and a lot has changed during the intervening years. It turns out that Google Earth has eight distinct views of the neighborhood, dating back to 1996. That first image is black and white, and there's a seven year gap until the next image shows up. Updates are more frequent thereafter.

I decided to create an animation to show the changes from 1996 to the present. (That capability is supposedly present in Google Earth but I couldn't make it work.) I took screen shots of each unique point in time, then created an animated GIF in Photoshop. Here's the result. Note: This is a very large file and the animation may not run if you don't have a lot of bandwidth. Feel free to right-click on the image and download it to your desktop to view if it stalls.

Aerial time lapse of Midland, Texas

There's not a lot of change during the latter years, although if you live out here, you'll be familiar enough with the neighborhood to spot the differences. But one thing I had never noticed before is that the development is has a distinct shape that's oddly familiar. I can't quite put my finger on it...but maybe you can figure it out...

Woodland Park...or Jurassic Park?

I, Cartographer
October 7, 2011 9:31 PM | Posted in: ,

Two months ago, I couldn't spell "cartographer," and now I am [on my way to becoming] one. As a Geographic Information Systems (GIS) specialist, my duties include generating and editing maps, and I've found the learning curve to be challenging.

There are actually two different challenges. One involves learning the systems we use for mapping. Most of our engineering and geological analysis tools (for those in the know, we use Petra and GeoGraphix) include mapping modules, as do many of our online sources of production and industry activity data. Our company has a proprietary mapping application, and I'm also learning to use ArcGIS, one of the most powerful standalone GIS programs in existence. So, thus far I've used about six different programs, none of which I'd ever seen before August 22nd. Fortunately, they all employ similar conventions and processes, so the transition from one to another isn't that tricky. But like so many things in life, they're easy to learn and difficult to master.

Ancient Map
Not one of mine.
The more interesting challenge is understanding the basic cartographic theories. I've always been fascinated by maps, but I never grasped the complexities involved with creating even the most basic maps, beginning with the fundamental issue of how one translates the features located on a sphere (the Earth - more correctly defined as a spheroid) onto a flat surface (a map displayed on paper or a computer screen).

The process of converting a three dimensional representation of the earth onto a two dimensional surface is called "projection," and humans have been experimenting with different kinds of projections for more than 2,000 years, trying to come up with the "best" way of locating geographical points of interest. The thing that all projections have in common is that they don't tell the truth...that is, none of them are completely accurate 3D-to-2D translations. They all distort one or more of the following characteristics: direction, distance, shape, or area. (For a nifty comparison of the more common map projections and their uses, advantages, and drawbacks, refer to this USGS resource.)

This is not just an academic or theoretical issue. The accuracy of maps has real and often significant implications. Maps can also be manipulated to achieve specific goals or serve specific agendas.

I'm reading a book entitled How to Lie With Maps by Mark Monmonier. I recommend it both as an easy-to-read reference for basic cartography, and as a primer on how maps are used to exert social, cultural, and/or political influence in ways that aren't necessarily ethical.

Anyway, while my specific job duties don't necessarily require that I understand some of the more esoteric cartographic principles, my natural curiosity about such things has led me to delve into a wide variety of resources, and if nothing else, I've learned how much I don't know. I've delved into the world of Great Circles, rhumb lines, sinusoidal projections, graticules, and azimuths.

That seems to be the story of my life. I keep telling myself that that's a good thing; it will keep my brain young. Someday, perhaps I'll even convince myself of that.

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