Raster Analysis

This lesson was on using raster tools within ArcGIS such as Raster Datasets, Aggregate, Raster Calculator, Focal Statistics, Reclassify, Slope, Weighted Overlay, and Least-Cost Path with a focus on using ModelBuilder to create reproducible workflows.

Cost-Path Analysis

Help pinpoint potential archaeological sites by estimating least-cost path trade routes from Winthrop, WA to coastal WA areas assuming trade routes follow rivers and routes with relatively low cumulative slope.

To speed up creating raster layers for this lesson, I resampled elevation data to 50m cells using Aggregate. I created a custom color ramp focused on low slope areas for my DEM which I overlayed with a hillshade. I used raster math to combine these layers into a single raster showing darker color at lower elevations and lighter at higher elevations to simulate an aerial view. Lastly, I used Focal Statistics to emphasize major geographic features while muting minor features to create a more generalized hillshade. The next part of the analysis was creating a cost-path based on my cost criteria following these general geoprocessing steps (specific tools in bold):

Calculate Slope
Calculate Distance to Streams
Mask Water bodies
Reclassify Slope (Least to Most Costly: 1-10)
Exclude Outliers From Distance to Streams (CON tool; remove areas <1500m to nearest stream)
Reclassify Distance to Streams (Closest to Farthest: 1-10, equal intervals)
Reclassify Water Bodies (Waterbodies = 1, Other = No Data)
Create Cost Surface (Weighted Overlay; Reclassed Stream + Reclassed Slope)
Calculate Cost Paths (Cost Distance; cost surface to source [Winthrop, WA])
Calculate Least-Cost Path (Cost Path; coastal cities as destinations, cost distance and backlinks)

A map including my final analysis:

My final model:

Aspect and Slope

I created a combined aspect slope raster using the skills from this lesson as a challenge and the off-google search wondering if I could map aspect and slope with the same raster. This strategy was based on suggestions and techniques by Cynthia Brewer, Ken Marlow, and Aileen Buckley and the ESRI R&D team. The design essentially uses simulated illumination (brightness) for slope, and industry standard coloration for aspect.