Wednesday, September 26, 2007

Map Projections

Tonight we had out first test, talked about Mary, who wasn't in class, and learned about Map Projections. Actually, we didn't talk about Mary who was out sick and I hope she feels better so she can come back and take the test. The test seemed like a fair assessment of our progress through the first four chapters.

To prepare for the test, I spent a lot more time in the textbook, and am really beginning to appreciate it. I love good technical writing, and this book is pretty good. The older Bentley repair manuals for various VWs I've owned over the years were great reading. They had these really well written paragraphs describing the functioning of the fuel injection system or something else complex, which made it understandable. Nowadays there is so much complexity in the cars, which requires so much volume of information that they don't have space for such frivolity.

The Map Projections are pretty interesting. No matter what mathematical method you use to translate a sort of sherical shape (the Earth) onto a flat surface (a map), you are going to have some sort of distortion. The most disturbing distortion to me is distortion of shape. The most common projection we have seen since we were kids is the Mercator projection. It is really handy for sailing ships on the ocean because you can draw a straight line from your location to your destination and just sail on that compass heading. The Mercator really isn't so good for showing accurate relationships of the size of features at various latitudes though. It shows Alaska about the same size as Brazil, which is actually 5 times larger. Being a very visual thinker, I am now in crisis because the pictures I have in my head of the world may be all wrong. ALL WRONG! OMG.

Wednesday, September 12, 2007

Eratosthenes and the Authalic Sphere

Tonight was some interesting material, and some of it was pretty dense. I'm going to need to spend some more time with our book. We're getting into the section of the book called "Earth-Map Relations" which I think is getting to the heart of what I like about maps. I'm thinking the core concept of representation might be what I'm attracted to. The Map represents a place on the Earth and as I said last week, it can help us understand and analyze complex data. I like things that represent other things in general, like Art in the broadest sense. Maybe it's things that not only (or necessarily) represent other things, but reveal something about them. Again, it's about the analysis. Strange then that most of my favorite Art is non-representational, or just about itself. Especially attractive to me about the maps is that they represent a place. For a long time I've had the experience of looking a road maps and having the locations or roads on the maps bring up memories of those roads or places. I also have gotten into looking at topo maps and trying to visualize what the area would look like if I was there.

We also did some interesting data importing tonight. We were looking at cellular phone radio transceiver tower information which we downloaded from the FCC. It was in a big 'ol data file that covered the whole country and was just in a delimited format. We imported it into excel and massaged it, which is also something I like to do. (I remember managing a mailing list for a non-profit entirely in WordPerfect 5.1. It was about 1500 people, and could pull out and print appropriate mailing labels based on criteria, on the tractor-feed dot-matrix printer.) Anyway, we had to eliminate the non-NC entries and then convert the Latitude and Longitude from Degrees, Minutes, Seconds notation to Decimal Degrees. That was kinda fun to automate the process, and doing it helped us learn how the two notations interact. Above is that map of NC with 818 cell towers, and we think that's not really all of them.

Back to Earth-Map Relations. I like the way that sounds. It partly reminds me of the Monica Lewinsky era, and I like the idea of the Relations among the Earth and its Maps. I better pull this political angle together with the title of this post now. I've been hearing for years that there are terrorists who "hate our freedoms." Like I also heard for such a long time way too many details about the Clinton-Lewinsky "relations." Tonight we learned about Eratosthenes, who in 250 BC came up with a way to estimate the size of the earth using a well and a post a few miles away. He got within about 4% of what we later calculated the circumference of the earth to be.
I think that was quite an accomplishment of conceptualizing and calculation. It makes me think of how the Arabic contributions to science and math are often overlooked in our Eurocentric
educations. Could that have led us to think they hate our freedoms?

Wednesday, September 5, 2007

Pete is not a Narc.

Tonight I had a thought breakthrough involving the word "analysis." I have had trouble explaining what GIS is about to people. I tell them that GIS is about making maps and combining that process with computer databases. Tonight I thought that analysis is the word I need to add to my description of what GIS is about. The power of GIS is making maps that help us analyse complex information.

Our first exercise tonight was about a water contamination scenario. The "map" I made is to the right. I'm using that term loosely because it is pretty far from what most people would call a typical map. The pink and red areas represent contamination of an underground aquifer, with the darker red indicating higher levels of contamination. The blue lines are water wells. The top of the blue lines are the surface of the earth, you can see some are deeper than others, and reach into the contamination area. The sort of beige shapes laying flat on the top of the land surface are different facilities in the area. The brown shapes that extend upward are graphic representations of facilities that are at high risk. The risk is based on if wells for the facility extend into contaminated areas. The darker color shows greater risk for facilities whose wells reaches into an area of higher contamination.

We have an interesting group in class this time. Josh is providing interesting information about Forests and chemical compositions. Some types of food that taste good can penetrate all the way into the nucleus of our cells and mess with out DNA. Yikes! Mary and I continued to eat this good-tasting but dangerous food and shiver in the overly air conditioned classroom. Mary brought us a sweater this week, but insisted on wearing it the whole class period while my fingers became so cold I could barely drape my 2D data layers onto 3D models.

It's true about Pete not being a narc. Apparently some of the Asheville sk8 culture had this impression of him. I can confirm that he is far too busy with GIS work, and blogs, and finding new features on google, to do any policing.