Lab 7 (Wk. 8)

Lab 7 - Working with Census Data

In this week's lab the objectives were to learn to find census data, use census data with ArcMaps, and learn to use GIS to create the three maps required.

The first map I have created below shows the Asian population in the United States by county in the year 2000. It helps use to see what the distribution of Asians is in our country. Some counties are as little as 0.0085% Asian, whereas other counties have as many as 46% of their residents from Asian descent. That is nearly half. By inspecting the map, we can see that more Asian people live on the coasts than southern or middle America. This makes sense as the West close is area of the United States closest to Asia and people came to find work. The New England region also so an influx of Asians immigrating to the United States through Ellis Island. I would be interested to see the same data for the latest census, to see if Asian Americans have spread over more of the country. 

Map 1: Asian Population Percentage. Data from 2000 Census.

The second map, provided below, is similar to the first map, except that I focused on African-Americans. Some counties in the United States are almost entirely African American, at roughly 87%. The county with the smallest percentage of African Americans has 0.01%. Unlike the Asian population, which is concentrated on the coasts due to logical immigration routes, the counties with the greatest black concentration are in the South. This can be attributed to history. Many Blacks were brought to this country long ago as slaves to work on plantation. The majority of these plantations were located in the southern United States.

Map 2: African American population  percentage by county. Data from 2000 Census.

Lastly, we come to the third map. The data in this map was provided by people who marked "Some Other Race" on the 2000 census. The distribution of these people is shown in Map 3. According to the census website, the vast majority of people who mark "some other race" are of Hispanic or Latino descent. The county with the highest percentage of Others reported about 39%. This translates to about 2 out of every 5 people. We can see that Others are heavily concentrated in the Southwest part of the US and Florida. This makes sense if most of the Others are of Latino. The Southwest United States like Arizona and California are very close to Mexico and South America and Florida is close to Cuba. People who emigrate from sadi countries generally stay in the areas of the US close to their home countries.

Map 2: People who marked "some other race." Percentage by county. Data from 2000 Census.

Overall, I had fun doing this assignment.  It is interesting to see how historical events which occurred well over 100 years ago greatly affect population distributions to this day. Once certain ethnicity are establish in an area they seem to stay there. Though many people may have traveled far to come to our great country, they seemed to not want to move anywhere once they arrived. It is also rather fascinating to see the huge range of counties with such little amounts of Blacks to such high amounts. 

The power of ArcMaps and GIS impressed me in this week's lab. The amount of data involved in these maps is not at all trivial, and ArcMaps handled it all quite gracefully. Even image rendering is done without any hiccups in the program. At this point, I have become very comfortable creating maps and changing projections and properties  as well as adding the basics like neatlines and legends. We also used the North American Lambert Conformal Conic projection this week, which made the information presented much clearer. 

Sources: www.census.gov/prod/2001pubs/c2kbr01-1.pdf
http://2010.census.gov/news/releases/operations/cb11-cn125.html

Lab 6 - Digital Elevation Models

Lab 6 (Wk. 7)

In this lab session, the goal was to become familiar with raster data and how to use it. The raster data we chose to focus on was a Digital Elevation Model (DEM). We made four maps using this data: an aspect map, a slope map, a shaded relief map, and a 3D map.
Elevation models are a great tool that allow people to present data in a realistic manner. It is an excellent way for people to be able to understand how elevation is changing in an area. It is much easier to use than a topographic map, for example. It is also more aesthetically appealing. The 3D map is very cool and interesting to play with. The virtual 3D effect is done well enough to not just be a visual gimmick, but is actually accurate and useful. When used in conjunction with the other maps I have posted here, it becomes very easy for the user to visualize what the mapped area actually looks like.  However, one must exercise caution because it can be very disorienting. It is very easy to lose your bearings while looking at the 3D map. The way I have presented the 3D map below, it is as if the viewer is looking towards the south from the north.

Lab 5 - Map Projections

Week 6 - Lab 5: Map Projections

As the title above states, this week's lab was all about different map projections. We learned how to create different map projections in ArcMap. Unlike last week, where we were given very explicit step by step instructions, this week we were more or less left to stumble our way through the software. Because it has been two weeks since our last lab, I had forgotten some of the things we had learned in ArcMap and had to spend some time re-learning general layout, controls, and functions.

The Earth, as we all know, is 3-D and spherical. Thus, it is impossible to create a two-dimensional representation of the Earth without some sort of distortion. Different projections distort different aspects of the map, and each projection is best for mapping certain things. Thus, depending on the situation, the "best" projection is usually a different one. It is for exactly this reason that ArcMap supports over 60 map projections.

There are three main categories or types of map projections: conformal, equal area, and equidistant. Conformal projections preserve angles. Equidistant projections maintain equal distances. Equal area projections maintain correct relative areas.

I will focus first on conformal projections. Conformal projections are characterized by the right angles at every intersection of a parallel and meridian. In order to preserve angles on the map, area and or distance are altered. For example, in the Mercator projection below, we see that Greenland appears much larger than it actually is. The distortion is very large near the poles. In the stereographic map neither distance nor area is preserved  Africa appears very small.  Conformal maps can be used in egocentric or propaganda maps to show certain areas as big and powerful or small and weak. They are also excellent for use in navigation.

Next we come to Equal Area projections. The two I have chosen to highlight below are the Cylindrical and Sinusoidal equal area projections.  In order to preserve area, distance and angles are compromised. These projections are useful when the size of a country or continent is important. In the cylindrical equal area projection, the area along the equator is not distorted, but other areas appear compressed.  In the sinusoidal projection, distortion is minimal along the prime meridian and equator.

Lastly, we come to the equidistant projections. In both the cylindrical and conic equidistant projections shown, distances from some relative point or line  on the map remain accurate in these projections. These maps can be confusing if the user is not clear on where the reference location is. These maps can easily be used incorrectly. The equidistant cylindrical projection preserves distances along the meridians, but no where else. The equidistant conic is convenient when mapping small countries, or for countries that extend mostly east-west, such as the former Soviet Union.