org.onebusaway.transit_data_federation.impl.shapes
Class ShapePointsLibrary

java.lang.Object
  org.onebusaway.transit_data_federation.impl.shapes.ShapePointsLibrary

public class ShapePointsLibrary
extends Object

Constructor Summary

ShapePointsLibrary()

ShapePointsLibrary(double localMinimumThreshold)

Method Summary

List<PointAndIndex>	computePotentialAssignments(List<XYPoint> projectedShapePoints, double[] shapePointDistance, XYPoint targetPoint, int fromIndex, int toIndex) Here is the idea: Given a shape as an array of XY Points, a range over those points, and a target point, find the closest location(s) along the shape for the target point.
List<XYPoint>	getProjectedShapePoints(ShapePoints shapePoints, UTMProjection projection)
void	setLocalMinimumThreshold(double localMinimumThreshold) When searching for the closest point along a block's shape, there may be multiple local minimums as a block potentially loops back on itself.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ShapePointsLibrary

public ShapePointsLibrary()

ShapePointsLibrary

public ShapePointsLibrary(double localMinimumThreshold)

Method Detail

setLocalMinimumThreshold

public void setLocalMinimumThreshold(double localMinimumThreshold)

When searching for the closest point along a block's shape, there may be multiple local minimums as a block potentially loops back on itself. This threshold (in meters) determines how close a local minimum should be if it is to be considered.

getProjectedShapePoints

public List<XYPoint> getProjectedShapePoints(ShapePoints shapePoints,
                                             UTMProjection projection)

computePotentialAssignments

public List<PointAndIndex> computePotentialAssignments(List<XYPoint> projectedShapePoints,
                                                       double[] shapePointDistance,
                                                       XYPoint targetPoint,
                                                       int fromIndex,
                                                       int toIndex)

Here is the idea: Given a shape as an array of XY Points, a range over those points, and a target point, find the closest location(s) along the shape for the target point. The trick is that there may be multiple good assignments, especially for a shape that loops back on itself. In this case, we look for assignments within our _localMinimumThreshold distance. There will typically be ranges of assignments that apply and we take the local min within each range. We then return each of these local mins as a potential assignment. There is an additional wrinkle when the section of the shape that loops back occurs where all the shape points are within _localMinimumThreshold of the target point. In this case, we no longer consider the local min for the section, but the individual local mins within the section. That is to say, if we find a local min and then the shape moves away and comes back, we'll consider the second local min as a new potential assignment. If no assignments are found within the _localMinimumThreshold distance, we just return the global min.

Parameters:

projectedShapePoints -

shapePointDistance -

targetPoint -

fromIndex -

toIndex -

Returns: