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Adam Franco edited this page Nov 18, 2016 · 14 revisions
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Vermont Route 17

Project website: roadcurvature.com

Curvature

Find roads that are the most curved or twisty based on Open Street Map (OSM) data.

The goal of this program is to help those who enjoy twisty roads (such as motorcycle or driving enthusiasts) to find promising roads that are not well known. It works by calculating a synthetic "curvature" parameter for each road segment (known as a "way" in OSM parlance) that represents how twisty that segment is. These twisty segments can then be output as KML files that can be viewed in Google Earth or viewed in tabular form.

Prepossessed files for the entire world can be downloaded at adamfranco.com/curvature/.

About the "curvature" parameter:

The "curvature" of a way is determined by iterating over every set of three points in the line. Each set of three points form a triangle and that triangle has a circumcircle whose radius corresponds to the radius of the curve for that set. Since every line segment (between two points) is part of two separate triangles, the radius of the curve at that segment is considered to be the smaller, larger, or average of the radii for its member sets. Now that we have a curve radius for each segment we can categorize each segment into ranges of radii from very tight (short radius turn) to very broad or straight (long radius turn). Once each segment is categorized its length can be multiplied by a weight to increase the influence of the most curvy segments. By default a weight of 0 is given for straight segments, 1 for broad curves, and up to 2 for the tightest curves. The sum of all of the weighted lengths gives us a number for the curvature of the whole line that corresponds proportionally to the distance (in meters) that you will be in a turn.*

* If all weights are 1 then the curvature parameter will be exactly the distance in turns. The goal of this project however is to prefer tighter turns, so sharp corners are given an increased weight.

Vermont Route 17

About & License

Author: Adam Franco
https://github.com/adamfranco/curvature
Copyright 2012 Adam Franco
License: GNU General Public License Version 3 or later