Big Brother is Watching Me

Took the Garmin GPS unit home for the weekend. Saved my track from work to home, with a waypoint or two along the way.

Back to the Salt Mines

Well, looks like we're open for business again after an enjoyable summertime break from the unholy concept of Having To Think About Stuff. But, once again, Pete commands us to not only Think About Stuff, but also seems to think that we should Learn Stuff, Study Stuff, and Blog about the Stuff We Learned from Thinking and Studying and stuff. So, time to clean the cobwebs, dust, moss, and potato chip crumbs from the ol' cranium; reboot the cerebellum, and revist GIS_World. Our destiny apparently now lies ahead in the Land Of Data Models. Models can be good. I enjoyed building model cars and planes and ships and stuff as a kid. Lingerie models are quite interesting. And I like Modelo beer. Frio Modelo cerveza es muy bueno.

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We started learning about data models/data formats, starting with the coverage. The coverage is a data format that was invented by the ESRI folks back when dinosaurs still roamed the Earth, but a lot of data in coverage form is still floating around out there, as the coverage was the dominant spatial data format for 30 years or so. It was introduced with Arc/Info, and stores spatial data in multiple feature classes. Nodes are used to build lines, and the lines (arcs) are used to build polygons. Tics serve as control points, and topology is stored by polygon adjacency to lines, each of which is stored only once, beginning at a "from" node, and ending at a "to" node. Attribute tables store the topology/data in fields such as COV.#, COV-ID, FNODE, TNODE< RPOLY, and LPOLY. It keeps track of which polygon is to the right or left of which line. The coverage takes a lot of book-learnin' to be able to build and maintain.
The next data format to come along was the shapefile. It has several advantages over the coverage-draws quickly, low maintenance, is read by several different software applications, etc. The shapefile is made up of a minimum of three files-a .dbf (attribute table), .shp (geometry-points, lines, etc.), and .shx (links to other files). Other files associated are .prj, .sbn, and .sbx. Shapefiles are not topological, they do not keep up with area, etc; but the Arc software keeps up with it, and area and such can be calculated manually in the attribute tables.
The next data format to spring from the primordial ooze was teh geodatabase. It is the Mac Daddy of spatial data formats, but is exclusive to ESRI. It stores data in feature classes that can be arranged in feature datasets. The geodatabase is topological, but duplicates data to do so unlike the coverage, which only stored each line once. The geodatabase automatically creates "SHAPE_LENGTH" and "SHAPE_AREA" fields, and automatically updates area, etc. values during editing. There are personal geodatabases (MS Access-based files, 2GB storage limit), file geodatabases (1TB limit), and three varieties of ArcSDE geodatabases which store data in a relational database program on a server.

Watched the ESRI CAD tutorial, and like Karl Childers, I reckon I didn't understand all of it, but I reckon I understood some of it. It dealt with georeferencing CAD data, translation of CAD to GIS, and vica-versa, showed how you could export GIS data in CAD format to allow you to profduce CAD drawings without CAD software, and working with map services, etc. I would have gotten a bit more out of it if I knew more about CAD data to begin with.

Asheville-the Annotated Edition plus: Hue's on First?

Continued with our labeling/annotation layer project, printed out some big honkin' maps and discussed them in a group session. The in-depth labels and annotations work in the last couple classes has helped a lot with real-world mapping-one of the most informative projects we've worked on so far.
We also went over some color theory and explored the world of hue, saturation, and value.

Togo in 3D!

March7:
Pete lectured on the fascinating nation of Togo. It is divided into 5 regions, all of which are much the same. Its main exports are dust and carbon dioxide, which are produced by the exhalations of the inhabitants. Like the Inuit and snow, it is said that the people of this charming little country have 3000 words for different types and degrees of "nothing".
We later put on the 3D glasses and had fun with some ArcScene and ArcGlobe exercises. We exaggerated the terrain of Death Valley, extruded and contaminated the groundwater of the San Gabrial Basin, interpolated people's thyroids in the Chernobyl vicinity, rendered Horse Cave, Kentucky asunder, flew through Massachusetts in a Unidentified Friggin Object, globablized Las Vegas, then stifled and blocked the sunlight of thousands of residents of California by draping a floating layer of ozone emissions over them. All in all, a fun class.

Missing Link Found!

Hydrology added! Landslides attached! USGS gages located! Hills shaded! Plus: thousands of residents smothered as a huge topographic map layer was glued down on top of a large portion of Transylvania County! Details at 11.

Searching For the Missing Link in Transylvania

Worked on the Transylvania County survey area assignment. Since some unnamed person who was soaking up sun in Mexico while we were freezing here in the subarctic regions left a link to a missing page of data and assignment info, we also studied improvisation. Heaven forbid, we had to actually think in order to find data and get our maps finished up. My brain still hurts.

Coordinated Conspiracies, Groundhogs, and Deja Vu

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View Larger Map

Went to class this morning expecting a substitute, but either
A: Pete hasn't headed to Mexico yet, or
B: He has genetically engineered a clone to teach his class while he basks in the Yucatan sun and drinks beverages with little umbrellas in them.

Got the tests back, (didn't flunk, thankfully) and had a lecture about x-y coordinate systems, scale, and such. Then we ran amock making Google maps. We created one on which we all conspired together online at the same time, and came up with a pretty good finished product. Nobody even got an eye put out. We are professionals. Do not try this at home.

On a sadder note (assuming that you have a fondness for fossorial rodents), I used my newly-acquired coordinating skills on the way out to determine that the expired groundhog in the middle of the campus entrance road is still located in the same exact x-y coordinates that he occupied last Friday, and still looks exactly the same after seven days on asphalt. Hmmm. I'm not sure whether he's in State_Plane_North_Carolina_FIPS_3200 or UTM_Zone_14_Transverse_Mercator, but I'm pretty sure he's still occupying the same coordinates. Either
A: This is an extremely resiliant expired groundhog, or
B: The campus staff removes the old expired groundhog every afternoon and replaces him with a fresh one each morning to extend the Groundhog Day celebrations from February 2nd to include the entire month. I don't know whether or not he saw his shadow.
Of course, in the Groundhog Day movie, Bill Murray keeps seeing things that look exactly like they did the day before. If I keep publishing this same post day after day, maybe it's happening again.