Lab6: DEMs in ArcGIS

     The region I selected for the Digital Elevation Model (DEM) analysis was located at the latitude and longitude coordinates of 36 51 27.03N, 117 44 23.82 W. The coordinates of the rectangle analyzed were as follows-- top: 36.9791666659, left: -117.805277779, right: -117.242777779, and bottom: 36.6699999993. According to Google Maps, these coordinates refer to the Death Valley National Park, specifically to S. Warm Springs Rd. in California. The Spatial reference utilized was the GCS_North_American_1983, referring to the Geographic Coordinate System using the datum North American 1983. The Death Valley National Park contains various geographic environments, ranging from valleys and salt flats to large mountains and canyons. In the particular area I chose within this national park, we see a rather large mountainous range surrounded by lower valley-like regions that are shaded in the Shaded Relief Map; the elevation for the mountainous region is clearly shown in the 3D map as well.

Lab5: Map Projections

Conformal:
1. Mercator

Planar: 10,112.118968 miles

Great Elliptic: 6, 934.483772 miles

2. Stereographic

Planar: 9,878.038997 miles

Great Elliptic: 6, 934.483772 miles

Equal Area:

1. Behrmann Equal Area Cylindrical

Planar: 8,763.089124 miles

Great Elliptic: 6, 934.483772 miles

2. Bonne

Planar: 6,730.704827 miles

Great Elliptic: 6, 934.483772 miles

Equidistant:
1. Equidistant Conic

Planar: 6, 972.480093 miles

Great Elliptic: 6, 934.483772 miles

2. Azimuthal Equidistant

Planar: 8,341.411788 miles

Great Elliptic: 6, 934.483772 miles

     Map projections are often utilized to portray a part or all of the Earth's surface on a 2-dimensional flat surface; it always comes with some distortion and each projection has its own advantages and disadvantages. There are mainly three types of projections-- conformal, equal area, and equidistant (as shown in above examples), each preserving a different element of shape, angle, direction, distance, or area since a map projection cannot preserve all these features. In this lab, we sought to study the mapped distance between two cities, Washington D.C. and Kabul, Afghanistan and the differences based on the particular projection we were viewing. We measured the distance using two different methods-- Planar and Great Elliptic. Planar simply measures the distance using 2-dimensional Cartesian mathematics while Great Elliptic utilizes the intersection at the surface by a plane that passes through the center of that ellipsoid as well as the start and endpoints of the particular segment.
     The first two map projections, Mercator and Stereographic, reflect conformal map projections that preserve shape, angle, and direction. The conformal map projection may be useful for any tasks that require viewing the correct shape of the countries. These map projections are characterized by the 90 degree angle that is maintained by the latitude and longitude lines. This projection does not, however, preserve area or distance; for example, in the Mercator Projection, Antartica is enormously represented in comparison to the rest of the world. This type of projection is also useful because its directions are fairly accurate, which may aid in navigation. The main drawback of a conformal map would be the increasing amount of distortion as you get farther from the parallels.
      The next two map projections, Behrmann Equal Area Cylindrical and Bonne, reflect equal area map projections that preserve the area, as suggested by the name. This projection is advantageous in that the viewer is able to obtain a realistic visualization of the correct geographic sizes of different entitites. In addition, this map projection can be useful in showing distributions of geographic characteristics, such as pollution and population density. Despite its advantages, some limitations are that this map projection does not preserve shape, angle, distance, or direction. As you get farther from the center, the shape, angle, and direction can get increasingly distorted. In addition, distances can also be inaccurately represented due to it not being preserved.
     The final two map projections, Equidistant Conic and Azimuthal Equidistant, reflect equidistant map projections, preserving the distance of the Earth's surface. This projection depicts true distances that can be useful in mapping buffer zones, as seen by the missile buffer zone in North Korea shown in the lecture slides. Although the distances are true, depending on the type of measurement (eg. planar, great elliptic), the distance can be vastly different. Some limitations of the equidistant map projection is that this projection fails to preserve shape, angle, direction, and area. In addition, although this projection shows true distance, it is merely limited to distances from the center of the projection outward; it does not reflect the correct distance between any two random points.

Lab4: Introducing ArcMap

     My ArcGIS experience went fairly smoothly; other than some rough patches following some of the directions, ArcGIS was a relatively pain-free system to utilize. As the system may look daunting at first glance with countless number of files and various buttons on the screen, the instructions are relatively straightforward and easy to follow which allowed me to pick up the how-to's of the system quickly. This advantageously allows for a greater, wider audience to be able to access and learn how to use ArcGIS, expanding the ability to share, learn, and analyze spatial information in our everyday world. However, despite its easy learning, the system has many files that are needed to be obtained, imported, or converted to create such elegant maps as the above, deterring its audience from even wanting to learn the ways of the program. I, too, had some difficulty understanding what all the .mxd files were before going through the tutorial.

     When following the instructions, I ran into trouble when it came to the zoom in/out button. As there seems to be multiple ways to zoom in and out, I often times found myself zooming in too much on one map thinking I was zooming in on another map and so forth. It took some time getting used to, as this part was surprisingly the hardest part of the tutorial in my opinion. This could potentially be a pitfall for first time users like myself as maneuvering the different basic functions of ArcGIS may not be comfortable at first. One must always make sure what diagram he or she is working with, what layer he or she is viewing at the moment, and how much to zoom in or out.

     Going through the tutorial step by step proved to be quite helpful and informative, as I was able to learn all the various functions ArcGIS had to offer. There is a vast number of functions that ArcGIS can do when it comes to drawing, creating, editing, and analyzing spatial data that is efficient and helpful to the daily user. Taking just one particular feature on a map, there seems to be countless number of things that could be done, from adding and subtracting layers to creating attribute tables and calculating the populations of particular regions. Without ArcGIS, I would imagine obtaining this kind of information would take a lot longer and maybe not even be as accurate as this system. One could even change up the presentation of the map, adding effects and legends as well as changing up the visuals, such as background, symbols, and colors to portray exactly what one wants.

     Despite the vast potential of ArcGIS, there is another major pitfall to this system. ArcGIS, due to its availability to anyone who is able to access and purchase the system, can be susceptible to potential misrepresentations by amateurs who are not quite familiar with the system or do not provide correct spatial data. This could be potentially dangerous as people within this field often share their spatial data with one another, working off each other to create more maps and to further analyze the information at hand. However, I do not believe that this poses much of a threat because of the efficiency and effectiveness of ArcGIS to provide correct and useful information to users around the world.