LAB #7

The first map displays the distribution of Asians in the United States. As an Asian, this map matches my impression of ‘Asian groups’.  In my map, there are 6 levels of Asians’ density, indicating the number of Asians in a county with darker colors for higher density and lower colors for lower density. As shown in the map, the Asian people concentrate in east and west coasts, while in many central parts there are few Asian people living. San Francisco is one of the cities with most Asians, so are New York and Los Angeles. Therefore we can see that in the areas mentioned, the population of Asian is in the highest level. In the place with highest rate of Asians the ratio is near half, meaning there is likely one Asian out of every two people.

 The second map displays the distribution of Black people in the United States. Like the Asians, most black people live in coast areas. What is more, there are much more black people in southern part of the U.S than in the north. This may be a result from historical reasons as we know south is the place of many slaveries. Same as the first map, darker colors indicate higher density of black people and lower colors indicate lower density of black people. Some counties in the central north have few blacks while some places have black’s ratio up to 86%.

The third map displays the distribution of some other race in the United States. This may include the Hispanic people. Darker colors indicate higher density of other race and lower colors indicate lower density of other race people.  Most of the other race people emigrated from Central American counties like Mexico. That’s why we see a lot of them in the counties in south, especially near Mexico. Also in Florida, where people speak Spanish as much as English, the color is very dark. However, the rate of other race people does not go very high, as the highest rate in the U.S is less than 40%.

In conclusion, the three maps above tell us how diverse the population of the U.S is. The places with most complicated mixture of races is near borders and coasts, where are homes immigrates most likely to choose as. However, my guess is with the time goes by, people with the particular races will scatter and move to everywhere in this country and therefore, we might not see concentrations as high as today’s. This does mean there will be fewer people in that race but a nation with better mixed population.

In this assignment, we choose the American Lambert Conformal Conic projection in GIS to show us a manifest and friendly map of population. This projection helps to explain the distribution of a particular race in the U.S with different color indicating different levels of rates. The final maps are not only easy for common people to understand, but also very clear and pretty, a feast on eyes. GIS is a powerful tool to analyze complicated geographical data and serve a very good demonstration purpose.

lab 6

Description of the area:

The area I selected is a small region in California near the Oceanside. It is close to a small hill called evergreen. This hill is not very high but its peak is relatively higher than the  surroundings. So it is suitable to make digital elevation model (DEM). The maps below lie between 32.938 degree (top) and 32.75 degree (bottom), and-117.15 degree (left) and -116.794 degree (right). The geographical coordinate system used is is GCS North American 1983.The following 4 maps represent different views and features of the terrain. These include a shaded relief model, a slope map, an aspect map, and a 3-D representation of the model.


DEM maps:

3D map

Lab: Projection

     Since the earth is a spherical, it is hard to correctly represent it on the 2 dimension map. There is no way to perfectly project three-dimensional earth surface into a two-dimensional planer surface. However, two-dimensional maps are very important in geographical application. So we invented lots of map projection purposes. Each of projection methods has its specific purpose and serves different function. For more effective use of map, one must pick the right projection. In this lab, I used three types of projection to project a world map; they are equal-area projection, equal distance projection and conformal projection. By comparing the differences and similarities of these three maps, I will discuss the significance of map projection.

     The first projection is equal area projection. It accurately represents area in all regions of the sphere, but it does not accurately represent angles. It accurately represents area in all regions of the sphere, but it does not accurately represent angle and size of a region. Each equal area map preserves area in a certain region or with certain conditions. Therefore it is essential to choose the right equal area projection depending on your region of focus. In addition, different equal area projection maps have different appearances. For example, Sinusoidal projection is like an ellipse. The polar areas in this projection shrink a lot. The shapes of two polar areas are distorted. In Bonne equal area map, the world is projected as a heart-shape. The north polar is distorted even more. But in both of them, the areas are accurately preserved.

     The next is equal distance projection. A useful application for this type of projection is a polar projection in which all distances measured from the center of the map along any longitudinal line are accurate; as shown above,  a polar azimuthal equidistant projection and conic projection are good examples . These two projections project the world from the north polar. In these two maps, distances and directions to all places are true only from the center point of projection. Equidistant maps both shared a common trait: their degrees of measurement from Kabul, Afghanistan to Washington, D.C. are about the same in both of the maps. Distances are correct between points along straight lines through the center. Though they are not very useful for navigation because the shapes are not well preserved, they are very useful in polar projection.

   The last projection is conformal projection. It preserves the angle and shape. Conformal map projections are frequently employed in large-scale applications, and seldom used for continental or world maps. Because the shape does not change, it is pretty useful in navigation. It is a big advantage of this projection. But it also has disadvantage; the distance and size are largely distorted. For example, 1984 PDC Mercator projection, the distance from Kabul to Washington D.C. is much longer than the distance in other maps. Furthermore,  the south polar area is much bigger than usual. In the miller cylinder projection, it is the same; the south polar is distorted and the distance is relatively larger.