Mod 3.1 Scale Effect and Spatial Data Aggregation

 

Scale effects the number of features that are depicted in a map, the overall length of these features, and if the feature is a polygon the overall area and perimeter length. For example a 1:500000 map of river networks would likely include major rivers and tributaries, but leave out smaller streams that may be found in a 1:50000 map.

Gerrymandering is a term used to refer to the redrawing of political districts in order to benefit a specific party. It can be measured via measuring the compactness of a political district. The measuring of a political districts compactness is accomplished by finding the Polsby-Popper score. The closer the score is to 1. the more compact it is which is desirable. The closer to 0, the more gerrymander a district.The screenshot above represents, what I calculated to be the district with the worst gerrymandering, North Carolina District 12.

Mod 2.2 Interpolation

 

This week I used the Thiessen Polygons, Spline, and IDW(above) interpolation methods to make a water quality map of Tampa Bay. IDW took the points that measured the biochemical oxygen demand(BOD) and assumed that the closer a raster cell was to the point, the more similar it's BOD would be. Thiessen Polygons creates polygons where inside is closer to its associated point than to any other point input feature.Finally, Spline uses an interpolation method that estimates values using a mathematical function that minimizes overall surface curvature, resulting in a smooth surface that passes exactly through the input points. Regularized splines modifies the minimization criteria so third-derivative terms are incorporated into the minimization criteria. Tension on the other hand, option modifies the minimization criteria so first-derivative terms are incorporated into the minimization criteria.