Custom Projections and Geogrocessing
Features Proximity Tools, Location Selection, and ModelBuilder
This lesson was designed to explore distortions of distance and area by different projections, examining geospatial metadata, customizing a projection for a map, and using geoprocessing tools to identify features within a specified distance of some other feature.
Yellowstone
This task was simple:
Evaluate projections of existing data and reproject if necessary
Produce a map of USGS ash fall predictions during a hypothetical Yellowstone Caldera eruption
Identify all the cities within 500 km of the caldera that may receive greater than 1 cm of ash fall
ArcMap allows the user to define their own projections. In my case, I wanted to define the extent of my equal area projection in order to reduce distortion around my subject area (Yellowstone). I extracted cities using a 500 km buffer around the centroid of the caldera and the SELECT BY LOCATION tool to create a new feature class containing the affected cities. Although the task only asked for cities within 500 km of the caldera, I wanted to show the actual ash fall predictions on my map. I converted tabular prediction data from the USGS into a classified raster for visualizing the modeled ash fall.
Density Analysis
This task was more complex:
Reproject or fix projections and clip existing data to project area (Whatcom County, WA)
Determine where roads and streams intersect
Determine density of road/stream crossings in each watershed administrative unit (WAU)
Create choropleth map showing crossing density in each WAU
This analysis was meant to be reproducible through the use of ModelBuilder for all data management and geoprocessing; my model can be seen below the map.
Here is my final model for my analysis:
