Tiger Conservation - Chapter 19

Chapter 13 Maps

Digital Data - Module Four

Well, our first test was Monday and it was relatively painless. Thanks, Pete, for giving us the "Learning Objecives" and "Terms to Know" with each module. For me, the hard part of this class is keeping up with this damn web log.
Wednesday, we began module four. Pete went through his slides of examples of digital data; essentially a list of prominent sources of information we can use in GIS. I then requested the SSURGO data for the continental US from the Soil Data Mart. I feel kind of bad about it now. I thoght it would just be an electronic request but I was 75th in line on Wednesday and four days later I have not received my data. There must be a room full of monkies working tirelessly to generate these data sets.
There is a long list of downloadable GIS data for North Carolina at the NC OneMAP site. On to chapter 19....


Geodesy, Projections and Coordinate Systems

OK, I must be a nerd. This stuff is fun. We learned about the shape of the geoid, Earth, and its measurment relative to the ellipsoid. There are several geographic coordinate systems used to develop Datums, or networks of known points on the Earth. The big lesson from this chapter is Know your projection! If you include layers in ArcMap that have undefined coordinate systems, the features will not line up properly.
I would love to learn how create datum points by Astronomical Observation. Pete, do you have a text for that?