Lab#6: DEMs in ArcGIS

The Geographical Coordinate System is GCS_North_American_1983. The Datum is D_North_American_1983.
Extent (in degrees)
Top: 41.273
Left: -130.998
Right: -129.344
Bottom: 41.886

These maps show the different perspectives of the original DEM model which focus on the region that is in the middle of California, nearing Northern California. To be specific, the area is of State Route 127, which is a California state highway that connects Interstate 15 to Nevada State Route 373 that passes through Death Valley National Park and curves near the Amargosa River. It begins at I-15 in Baker, which is the end of the Greater Los Angeles and the Las Vegas metropolitan areas and the start of Death Valley. The main road runs parallel to Salt Creek and Silurian Lake as it crosses the Valjean Valley, making its way along the southeastern edge of Death Valley National Park. SR 127 cuts through the mountains as it enters Inyo County then concurrently with State Route 178 through Shoshone. In the DEM Hillshade and 3-D models, areas that higher and lower in elevation are easy to pin point. On the slope map, we can see that there are many areas of high slope, because SR 127 cuts through mountain ranges. The aspect map is not a good representation of SR 127 because it does not clearly distinguish the high mountain slopes and the flat road.

Lab#5: Projections in ArcGIS

Map projections are unique ways of representing the surface of the Earth or some parts of the Earth on a flat surface such as a map or a computer screen. They greatly enhance the graphics and convey the information in distinctive manners. Since flat surfaces cannot fully convey the actual shape and grooves of the Earth, we must utilize distortions to try to have a better understanding of the Earth. We can use elements like “conformality”, distance, direction, scale, and area to distort the Earth’s surface to better meet the different ways we can look at the Earth’s surface. With distortions, there exist many inaccuracies but map projections help to put less emphasis on these errors and more on the specific method of projecting the Earth’s surface. This simply means that distortions are obviously not perfect and many of them are efficient projections of the Earth’s surface, however, determining the most effective type is significant. For this assignment, I will focus on the three types of projections: conformality, distance, and area.

Essentially, conformality is the specific scale of a map where any point on the map is the same in all directions. This is also called “conformal”. This is when the Meridians, which are longitude lines and the parallels, the latitude lines, intersect to form right angles. The shape of the Earth is preserved locally on these types of maps. I used the Mercator and Gall Stereographic map projections, two examples of conformal map projections, to portray the Earth’s surface. The most distinguishable “errors” on these maps are the following: Antarctica’s surface area seems much larger compared to the rest of the Earth; most of the area for all of the continents seen on the map is misleading because Africa seems to have similar surface areas as North and South America; both the Mercator and Stereographic projections generated similar distances between Washington D.C. and Kabul.

An equidistant map portrays distance in a way that it is the same from the center of the projection to any points on the map. While conformal preserve the shape of the Earth locally, equidistant maps preserve distances along the parallels of different places on the map. I used the Equidistant Conic and Sinusoidal styles for equidistant projection. These are two significant ways of transmitting information because the Equidistant Conic projection distorts the direction, area, and shape away from the standard parallels and instead, portray those areas that are near to and on one side of the equator, which means that the central meridian or the equator are not altered. The Sinusoidal projection is an important tool because the north-south and east-west scales are the same everywhere from the central meridian. Interestingly, the distance on the map between two parallels is smaller than the distance between the two points on the same meridian.

Equal-area maps look at areas throughout the entire map in order for all the mapped areas to have the same proportional relationship to the areas on the Earth that they represent. Even though the projections that I used, the Mollweide and World Hammer-Aitoff, are visually very similar, there is a slight difference where the Mollweide projection has straight parallels of latitude but the Hammer displays curved ones. Hence, it is important to notice that they are both pseudocylindrical map projections generally used for aerial, global views of the Earth. These projections leave out accurate measures of angle and shape in order to display the truest depiction of area. The equator is shown as a straight horizontal line and perpendicular to a central meridian, only half the length of the equator. The other parallels are compressed near both poles while the meridians are spaced equally around the equator and form a perfect circle at 90 degrees east and west.

Lab #4: Introducing ArcMap

In order to analyze the potentials and drawbacks of geographic information systems, we must understand what GIS entails. A geographic or geospatial information system (GIS) is a unique way of capturing, managing, examining, and displaying all types of geographically referenced information through mechanisms like hardware, software, and data. Quite simply, GIS unifies cartography, statistical analysis and database technology. Through GIS, we can see the world and even our local communities by understanding, questioning, interpreting, and visualizing the accumulated data. By truly adapting GIS we can reveal unique relationships, patterns, and trends in real life via maps, globes, reports, and charts. GIS can help us answer countless questions when we look at our data in a way that can be easily comprehendible and accessible. There is no way of counting exactly how many people benefit from GIS today and they range from enterprises to average students. This is because it has so many uses and purposes that it can be witnessed in occupations which we would not expect GIS to be needed such as: archaeology, public utility management, natural resource management, precision agriculture, emergency management, Environmental Contamination, and aerial video and localized search engines.

This lab assignment was nothing like what I have ever done so at first, it was definitely difficult to navigate through the program even though the directions were fairly simple. I was getting discouraged in the beginning and did not believe I would finish all 58 pages of the tutorial but as I became more accustomed to the software, everything became easier and in the end the assignment was a rewarding experience. I believe the ArcMap GIS program has made grounds for tremendous possibilities and even many pitfalls. GIS programs like ArcMap, help students who are unskilled or minimally educated at creating maps to produce intricate maps and I feel very privileged to be able to have had first-hand experience with it. Now I understand just how easy technology makes it for everyone through the use software like ArcMap to generate their own maps.

One of the best features of GIS is that it has made the world somewhat of a smaller place and helps people connect with locations far away. By being able to color code and include specific symbols for different points on a map, GIS has great potential in terms of making maps more personal and even easier to understand. After we gather some type of data of a certain region, we can start analyzing and appreciate what that region has to offer. Because it brings together such a dynamic set of cartography, statistical analysis and database technology, GIS can even assist with making important decisions. For example, with wildlife conservation in sub-Saharan Africa, people involved with conserving elephants including the local tribes, conservation groups, and tourists can all work together by tracking the huge mammals with GPS devices, collecting data and conserving the different elephant species by mapping out where each species lives and try to prevent illegal poaching, push conservation laws and educate the local tribes and tourists. Rapidly developing technology like Smartphones and GPS devices with the help of their extremely spot-on parallel multi-channel design makes the fact that the world has become virtually closer more conceivable.

With every good thing, follows something bad. The pitfalls of GIS include the following reasons. Even though technology is in a sense faster, more precise, and oftentimes more reliable than people, because it is man-made, it is not perfect. There is no doubt that it is not always accurate and reliable. Computers and phones are often faulty and internet service isn’t readily available everywhere on Earth. Certain atmospheric factors and other sources of error can also affect the accuracy of GPS devices and phones with GPS embedded in them. Also oftentimes, GIS makes people dependent on GPS devices and cannot go anywhere without them. With the increasing popularization of GIS in decision making, many people have started to analyze its social insinuations. The most common argument that exists surrounding the concept of GIS is the idea that production, distribution, utilization, and representation of geographic references have a large correlation with the social context. For example, it is extremely concerning that there are many people who corrupt the positive usage of GIS to plagiarize other people’s work and completely disregard copyright, privacy, and censorship. It is really unfortunate that some people take advantage of GIS and sometimes use it to merely gain a profit.