Q1: I used the Intersect Tool on the second trial of the exercise. I had the results of both methods on the map, and compared them by turning one or the other off and on several times. I could not find any differences. The Intersect Tool was what I had expected to use as I worked the problem the first time. Using the Union Tool was a good demostration of the princilple that there are always several ways to reach the same result.

Q2: I used the Erase Tool to eliminate the parts of the selected areas that overlaped the conservation areas. That seemed to be the most efficient way to remove sections that needed to be excluded in the final analysis.

Q3: There were 72 features in the final layer. The largest has an area of 7,765,034 square meters, and the smallest is 748 square meters.

Flashback to Data Search

My primary problem with this section of the lab assignment was re-projecting one DOQQ. All four came from the same source, and I thought were in the same projection. But there is apparently a critical difference between GCS_North_American_1983 and GCS_North_American_1983_CSRS. I didn’t notice the minor difference at first, until the latter could not be re-projected. ArcCatalog closed abruptly each time I tried to perform the operation. I eventually downloaded other DOQQ files and had no problem.
I added the USGS Quad background, which I clipped to the county boundary. I did not have to clip my other layers (I was able to download already clipped layers for my county), and wanted to practice that part of the lab.
I was eventually able to research CSRS, and discovered it is the Canadian Spatial Reference System, which is a 3-dimentional system. It includes data not only on height (elevation?) but gravity and earth rotation. It’s no wonder ArcCatalog choked on it.
I don’t know why one of a set of four DOQQ files was in that format, unless LABINS is in the process of converting to that format.

Module 7: Data Editing

Projection: Florida State Plane North

I have actually done this type of editing before. I used to create a lot of vector maps my office needed from georeferenced aerial photos. I did learn a few new methods and updates to the software. My biggest problem is being too perfectionist in following the roads and building outlines. I tend to use many more vertices than are needed at the scale the map will be used.