Lab 7

The population density of Asian Americans is relatively low across the continental United States. Most Asians reside on West Coast and East Coast, with the highest density 30.8% in San Francisco County, California. In the Midwest and other parts of the continental US, Asian population spreads out randomly with densities generally below 2.28%. The pattern of the population is formed due to geographical locations between Asia and North America. Since Asia is to the west of the US, the first place immigrants from Asia arrived at is West Coast. Thus, the population density is high in counties on West Coast. Since New York and surrounding cities are always attractive places to immigrants because of abundant job opportunities and modernization in those cities, a lot of Asian immigrants also reside in those areas.

From the map, we can see that the population density of African Americans is highest in the southeastern part of the US, with the highest density 86.5% in Jefferson County, Mississippi. The population densities of many counties in Mississippi and Alabama are above 50%, while in northwestern part of the US, the population densities of most counties are below 10%. In the history of the United States, black slavery were brought from Africa to the southeastern part of the US and most of their descendants still stayed there.

The population densities of other minorities are highest in counties in California, New Mexico and Texas, with densities generally above 10%. The highest density is 39.1% in Imperial County, California. However, the densities are quite low in Midwest and other parts of the US. They are generally below 5%. From the map, we can see that the places with highest densities of other minorities are on border with Mexico. Thus, we can imagine that the dominant ethnic in this category is Hispanic. Due to the proximity to Mexico, most immigrants decided to settle down in South and Southwest US.

In general, I find that the population densities of Asians and other minorities are highest in the southwestern part of the US, while the density of African Americans is highest in the southeastern part of the US. Across the continental US, there is no county with a population density of Asians or other minorities over 50%. The census experience I had with GIS is quite interesting and useful. I not only know more about the geographical distribution of population densities of different races, but also developed my GIS manipulation skills of integrating data from external sources into the software. The series of census maps allows me to analyze real-world problems in population distribution. Overall, GIS is quite useful and powerful in map-making and geographical data processing. We can generally utilize it with ease once we know the basic methods of manipulation.

Lab 6

The location I selected is a mountain area near a small city called Chico in North California. By the slope map and the 3D map, we can see elevation is obviously rising from west to east as from the plain area to the mountains. We can also get insights into what direction a specific area of the DEM faces by looking at the aspect map. The topographical features of this location, which are presented by GIS, are pretty telling.

Extent Information:

Top: 40.00°N

Left: 122.00°W

Right: 121.00°  W

Bottom: 39.50°N

Geographic Coordinate System:

GCS North America 1983

Lab 5

Measurements of the distance between Washington, D.C. and Kabul

A map projection is a process that transforms the 3-D irregular sphere, Earth, into a 2-D flat surface, which is easier to work on than a 3-D model of Earth. Map projections are very important for us to understand features on Earth based on a 2-D ground, such as the relative positions of two continents and the distance between two chosen coordinates. A projection can be classified by the type of projection surface, onto which the globe is conceptually projected. Some of the surfaces that are frequently used are planes, cones and cylinders. The three sets of maps shown above are classified as conformal, equal-area and equidistant according to the properties of the model they preserve. Each of the three kinds has its own certain advantage of learning a particular feature on the map.

The conformal map projections, for example, preserve angles locally. As we can see on both the Mercator and stereographic maps, the pairs of meridian lines and parallel lines are always intersecting at 90 degrees. Thus, conformal maps are usually quite useful to guide our directions and find relative positions of two coordinates, especially over small areas. The equal-area map projections preserve area on maps. Like the Behrmann equal area cylindrical map and the cylindrical equal area map, area is maintained. Therefore, we can compare the real areas of two regions on those maps in a relatively accurate way. Equidistant projections preserve distance from some standard points or lines.  While the equidistant conic projection can be based on one or two standard parallels, the two-point equidistant projection shows the true distance from either of two chosen points to any other point on a map. The planar distance between Washington, D.C. and Kabul on the equidistant conic map is 6972.48 miles, which is closest to the true distance between the two places among all the six projections.

As we already know, all the map projections have some certain degree of distortion. Take the Mercator projection for example. Although the projection maintains local angular relationship, area on this map is distorted. How could Greenland be larger than China or Australia?  For the equal area projections, there is always some distortion of shape and direction on maps. For example, the cylindrical equal area map has severe distortion of shape and scale near the poles and the distances are generally distorted except along the equator on the Behermann equal area cylindrical projection. Both of the equidistant projections contain some sort of distortion on shape and area. We can see that all those kinds of distortion could lead to people’s misunderstanding of the true geographical properties of the world. This is a potential peril we should certainly avoid. Thus, it is truly crucial to select a projection to meet our purposes or interests of an analysis.

Despite the unavoidable flaws of any of the map projections, map projections offer us great insight into geographical properties of our world. By using different sorts of projections, we can focus on analyzing different spatial information to meet our target goals. Thus, map projections have the potential to allow us to compare distinct features of Earth and broaden our knowledge on our positions and surrounding areas. 

Lab 4

At first glance, this lab seemed pretty intimidating and tedious with so many pages of tutorial instruction. However, once I settled down to start from the first page, I realized this task would be interesting and really useful for broadening my scope of knowledge. Having some programing experience in C++ and Matlab, I did not find it too hard to do programing with ArcMap, which looks quite straightforward and easy to use. Also, the step-by-step instruction on the tutorial is very clear to understand. However, I did spend a lot of time doing this project and enjoying the process of learning it. Comparing to the google mashup we finished in last lab, ArcMap does have some benefits for mapmakers and users.

One of the most obvious benefits of using ArcMap is its accuracy. For example, when we try to make a new road on a map, we can determine its length, direction and shape by using mathematical calculation, which is far more accurate than random drawing. Also, we can pinpoint a location by looking at its coordinates, which is provided by the software. Another feature is data managing. In this project, we need to calculate the population density through ArcMap. By setting the mathematical equation for the calculation, we can easily get the result of the population density from the existing data. It is also possible to make diagrams or charts on the map to summarize data. Moreover, we can create legends and scale bars to further illustrate the map.

The function of organizing data and presenting them on a map makes ArcMap a powerful tool for information managers and scholars of geography.  Like one of the exercises we did to show the population density distribution in the area, the ArcMap perfectly visualized the different sets of the population density on the map. These kinds of features of visualization allow managers to easily make decisions and solve problems. For example, marketing managers would like to know where to post ads or built a shop is most beneficial for their companies. They would probably like to find some places of dense population by looking at the map with that information. Also, they would like to see different sets of data that are divided into different layers of themes for more informative and clearer illustration. This is actually one of the ArcMap’s functions.

Some pitfalls of GIS lie in its complexity of its manipulation. Although the programing of ArcMap is already user-centric comparing with some other programing languages, it is still more complicate to manipulate all those data than the user-friendly neogeography. Since the starting tutorial of ArcMap is already a 56-page manual, we can imagine how hard it is to actually master this software. A layperson would not prefer to use ArcMap by extracting all those files and carefully examining data rather than create a highly individualized mashup by simply clicking the mouse. Also, software like ArcMap is quite expensive for an individual to buy.

In sum, ArcMap is quite useful to learn how to do concrete and coherent data analysis. The poster I end up making is also quite pleasing in an aesthetic way.