Tuesday, February 26, 2013
Lab 6
Extent data:
Top: 39.829166666
Left: -105.788888888
Right: -104.96944444
Bottom: 39.3838888883
Spatial reference:
Angular unit Degree (0.0174532925199)
Datum: D_North_American_1983
Use of the ArcGIS software for this activity has become easier, but the interfaces are still not very intuitive, and the instructions to complete the lab make references to buttons, names or clickable areas in the software that don't exist or are outdated or changed. This makes it always challenging to move from one step to another as it takes quite a bit of guessing sometimes. I continue to find the instructions difficult to follow since they don't accurately reflect what we have on the screen.
Wednesday, February 20, 2013
Lab 5
Map Projections.
There is great significance in the availability of so many varieties of map projections. One may very aptly illustrate a point or series of points or data collection by choosing the projection that most strongly or clearly references such points or data. The disadvantages of so many options for projections lie in what and how much each distorts from the real world, and in how we must make our best educated decision as to our choice of projection.
We know that a mercator projection, for example, is perfectly accurate around the equator and no where else, but it became highly useful for nautical purposes because of how it represents lines of constant course. A stereographic projection proves almost exclusively valuable in planetary mapping for crater mapping.
Equal area projections sacrifice accuracy of shape and of angles but are more accurate of the proportions of that area. The Mollweide projection is a good example of this. The Bonne projection focuses on the area accuracy mostly around the central meridian and the standard latitude where the shapes are not distorted.
Equidistant projections preserve distance from a standard point or line.
The plate care projection introduces such distortions that it is not suited for navigation, for example. Polar projections are useful applications of an azymuthal equidistant projection.
The risk in choosing a highly customized projection is that while it may enhance our view of a certain point, it can highly weaken the perspective on another, giving a false sense of reality in general. We must choose the one that best illustrates our point but which also introduces less distortion on other points.
Wednesday, February 13, 2013
Lab 4
The Arc map software proved a bit more difficult to learn than I thought. Its tutorial was designed for an earlier version of the software that had significant differences in look and instructions. The software also was not as intuitive as I would have imagined.
Once one becomes familiar with how to use it, I can imagine this software to be highly useful to GIS. It offers the possibility to produce highly customizable maps through its many tools for data inclusion.
In my opinion, however, the software still has a very outdated look and requires navigation through many panels or tool sets to complete simpler tasks.
I have yet to familiarize myself better with the software to get a better idea of its uses and exactness in illustration but so far, I am excited about continuing to use it.
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