May 7, 2010

Final Project: Choropleth and Isarithmic Mapping

Overview

In an increasingly visual world, the effective presentation and portrayal of spatial information is crucial. Geovisualization provides a means to represent spatial problems and visually engage an intended audience. To effectively portray any geographic information, an understanding of the science and art of mapmaking are crucial. Furthermore, cartographers must be aware of the new mediums used to display geographic information. Blogs, electronic presentations, smart phones, and internet mapping provide potential outlets for a cartographer’s work. Effective geovisualization also demands an understanding of Geographic Information Systems (GIS) their use data management, development, and classification. Finally, an increasing abundance of freely available geospatial data allows cartographers to produce high-quality maps from census and other data sources. Using the concepts and data listed above, two-high quality thematic maps will be generated from online geospatial data and presented on BlogSpot.

Study Area

Three criteria were used to select the map study areas for this exercise. First, the selected regions should not have been used for Geography 390 exercises; therefore, Idaho, Boulder (Colorado), and Buffalo (New York) were excluded from the data pool. Second, the two selected regions should be geographically distant and distinct. Third, the mapped region should include locations I have visited. To satisfy these demands, the state of Wisconsin and San Juan County in Washington were chosen. These areas were not used in lab, are geographically distant/distinct, and are places I have a visited.

Mapping Technique

For this exercise, population density and elevation were mapped. Given the unique spatial distribution of population density and elevation, two mapping techniques were employed. Choropleth mapping was used to represent population density; this mapping technique is ideal for continuous standardized variables with abrupt variation. In this case, Wisconsin population density was mapped by county. Alternately, equal-interval isarithmic mapping was used represent elevation in San Juan County; elevation typically occurs as a smooth, continuous variable across a landscape, indicating isarithmic mapping as the ideal mapping technique.


Figure 1. Map of county population density in Wisconsin.


Figure 2. Map of San Juan County in Washington State.


Figure 3. View from Mount Constitution, the highest point in the San Juan County at 2408 ft above sea level.



Figure 4. Bellingham, Washington as seen from Mount Constitution. [Bellingham is in the middle-left of the photo.]

Figure 5. One of the ferries accessing San Juan County. The county is only accessible by boat or plane.


Figure 6. Ferry dock on Orcas Island.