Topic 3 Module 1: Scale Effect and Spatial Data Aggregation

This week we were involved in scale effects on raster and vector data, gerrymandering. The relationship between scale and geometric properties is that the large-scale maps show fewer properties than the small-scale maps. This is due to the generalization where information is “lost” because fewer vertices are used to represent features. Along with exclusion, where scale matters and can cause a decrease in the level of hydrographic feature detail. After reading the Goodchild, M.F. 2011 article and seeing other Esri documentation on the web I understand that my findings in this lab are as expected and that I have lost detail as the scale changes. The level of detail of features represented by a raster or vector data is often dependent on the cell (pixel) size, or spatial resolution, of the raster/vector. The cell must be small enough to capture the required detail but large enough so computer storage and analysis can be performed efficiently. However, more is not often better especially when considering compuation times and data storage limits. As for gerrymandering, it has a very negative history and is defined by manipulating the boundaries of (an electoral constituency) so as to favor one party or class. Basically it is the redrawing of polygons and can be measured by compactness and community. Below is a screenshot of a district with failing to have district 'compactness'.