For the detail-oriented, these are 100%-algorithmic images generated from MapZens Migurski-inspired October 2014 OpenStreetMap Metro Extracts as follows. First, we assign each linear street segment a compass-heading-based tone from a modified sinebow, where a 90 degree directional difference corresponds to a full color revolution, so that roads at right angles to each other have the same hue. Then, to render each point on the map, we use Proximatic, my custom high-performance k-NN engine, to calculate the length-weighted average of the colors assigned to the nearest 500 meters of street, keying render weight to the local degree of parallelism/orthogonality (derived in a similar mod-90° vector space), with rolloffs for outlying roads and territory.
