GIS5935 Module 3.1: Scale Effect & Spatial Data Aggregation

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The final week of the GIS Special Topics course and we get to end it on Scale Effect & Spatial Data Aggregation. We got to explore how vector and raster data can be affected by scale and then how gerrymandering affects boundaries and communities.

The first part of the lab gave us different hydrographic features of varying scales to learn about the relationship between scale and the line and polygon features of waterbodies throughout Raleigh, North Carolina. As expected, geometric features of the water lines and polygons were more defined at larger scales versus small scale, but it was cool to see just how simplified features became and how to calculate that through area, perimeter, and polygon counts! We also dived into DEM resolution in King Range Wilderness of California and how as the DEM cell size changed, from 1 m up to 50 m, the resolution and average slope calculated from that DEM dropped then gradually showed signs of tapering off.

Part 2 brought us back to a country scale, looking at the entire U.S. to view and measure gerrymandering through the compactness of a boundary through the Polsby-Popper formula: (4πA) / (p^2). As described by Bolstad and Manson (2022, p. 382), Gerrymandering is the "process of aggregating neighborhoods to create majority blocks for political advantage" thanks to the Massachusetts governor Elbridge Gerry who created a salamander-shaped political district (Bolstad & Manson, 2022, p. 382). Similarly odd shapes were discovered during my calculations, including this district shown below in Philadelphia.

Screenshot of an example of a district with bad compactness. Fun fact: this district was once known as "Goofy kicking Donald" because its deformed shape resembled the two iconic Disney characters! Historically, this Philadelphia district goes up there as one of the most infamously egregious district boundaries in the U.S. (Tomik, 2025).


References

Bolstad, P., & Manson, S. (2022). GIS fundamentals: A first text on geographic information systems (7th ed.). Eider Press.

Tomik, J. (2025, August 22). Philly suburbs were once poster child of gerrymandering for district shaped like Goofy kicking Donald Duck. PhillyVoice. https://www.phillyvoice.com/philly-suburbs-gerrymandering-goofy-kicking-donald-duck/


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