Census 1990/2000

The map titled “Number of People, 2000” shows the numbers of people present in the United States in the year 2000. The various population values are broken up according to amount which is represented by several different colors. The values for this map were calculated by the census of that year. The color ramp selected to represent the kind of data shown in this map was best because the colors are all in the same color family, each just a slightly darker or lighter color then the color above or below it. The darkest color represents the highest value and the lightest color represents the lowest value which makes sense to the map reader.

The map titled “Difference, 1990 to 2000 Number of People” shows the amount the population changed by in the United States from 1990 to 2000. The various population change values are broken up according to amount which is represented by several different colors. The values for this map were calculated by subtracting the number of people present in the year 1990 from the number of people present in the year 2000. The color ramp selected to represent the kind of data shown in this map was best because it is logical to the map reader. The three highest values of the data are all colors of the same color family. The highest of these three values is the darkest color, while the lowest is the lightest. The two lowest values of the data, which are both negative, are lighter and darker versions of the same color as well. The color that represents the first values that aren’t negative in the data is a dark gray color, which is a good representation because it’s a sensible way to let the audience know the values are no longer negative.

The map titled “Percent Change, 1990 to 2000 Total Population” shows the percentage the population changed by from 1990 to 2000. The various values are broken up according to amount which is represented by several different colors. The values for this map were calculated by subtracting the number of people present in the year 1990 from the number of people present in the year 2000, dividing that by the number of people present in the year 1990, and then multiplying it by 100. The color ramp selected to represent the kind of data shown in this map was best because it is logical to the map reader. The highest values of the data are represented by dark colors, while the lowest values are represented by light colors which makes sense to the map audience.

The map titled “Population Density, 2000” shows the density of the total population in the year 2000. The values for this map were calculated by dividing the total number of people living in the given area by the total land area. The color ramp selected to represent the kind of data shown in this map was best because it is logical to the map reader. The highest and lowest values of the data are in dark contrasting colors. The lowest middle values of the data are in similar light colors which represent a large majority of the map. The highest and lowest values of the data are easy to spot on the map because they greatly contrast the lightly-colored majority of the map.

DEMs in ArcGIS

The area I selected to base the following images upon is an area of Colorado Springs, CO. I chose this area because it contains a lot of mountainous terrain as the Rocky Mountain Range runs through it. The area of Colorado Springs, CO depicted in these images is located at 38.8338889, -104.8208333. The datum used in creating these images was GCS NAD 1983 and the UTM zone of the datum is zone 12. The projection used in creating these images was a transverse mercator.

Image #1: Shaded Relief Model

Image #2: Slope Map

Image #3: Aspect Map

Image #4: 3D Projection

Map Projections in ArcGIS

Projection #1: GCS WGS 1984/Mercator

WGS 84 is a global datum complete with a horizontal and vertical datum. It defines the shape of the earth and is complete with latitude and longitude coordinates. The Mercator projection is a cylindrical projection that preserves the direction and shape of features on a map. The WGS 84 differs from the Mercator projection as the WGS 84 isn't a map projection, it's a datum which just defines the origin and orientation of a map. Selecting the datum is the first step in creating a map projection. WGS 84 could be used in portraying a Mercator projection.

Projection #2: Cylindrical Equal Area/Sinusoidal

In the Cylindrical Equal Area projection, the area is preserved while the shape and distance is heavily distorted. It is made using a cylinder and compresses north-south latitudes. In the Sinusoidal projection, the area is also preserved while the shape is heavily distorted and the distance is preserved along parallels. It is a psuedocylindrical projection and a cylinder is also used. In the Sinusoidal projection, the north-south scale and the east-west scale are the same throughout the map. In both of these map projections, the features are relatively similar as they get stretched and distorted towards the north and south. The Sinusoidal projection, however, portrays the features at a much smaller scale than the Cylindrical Equal Area projection.

Projection #3: Equidistant Conic/Equidistant Cylindrical

In the Equidistant Conic projection, distance is preserved while shape and area is distorted. It is made using a cone and has constant parallel spacement. In the Equidistant Cylindrical projection, distance is also preserved while shape and area is distorted. It is made using a cylinder and north-south distances are neither stretched or compressed. In the Equidistant Conic projection, features seem to be compressed, while in the Equidistant Cylindrical projection, features seem to be stretched south a bit.