openplans/OpenTripPlanner — pull request #944 by mentaer (2012-12-25 18:21:54+00:00)
Title: New isochrone class for OTP Analyst to calculate access sheds, such as walksheds.

The class generates and parses the ShortestPathTree for a given location to extract all edges within a provided time limit (parameter: walkTime, as the original purpose is the creation of walksheds). With a second parameter the geometry type of the result can be set. The result can be:
(i) the points - all intersections/nodes within the time limit
(ii) the edges - including sub-edge segments until the time limit
(iii) the enclosing hull (polygon) of those edges or points - normally the concave hull for the edges, but for large times, the hull of the points.
See the javadoc for details.
Tests with other modes have been (successfully) performed.

Unfortunately there are still some edges that seem to need special treatment when calculating sub-edges (similar to crescents/u-shaped roads that return to the main road). Indicator for these edges are traverse speeds that exceeds maximal user set speed or maximum allowed road speed limits (see LOG.debug(...) outputs).

Note, the aim is pretty similar to the analyst work by A. Byrd but with raster tiles as output.