org.opentripplanner.graph_builder.linking.VertexLinker Maven / Gradle / Ivy
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package org.opentripplanner.graph_builder.linking;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.Envelope;
import org.locationtech.jts.geom.GeometryFactory;
import org.locationtech.jts.geom.LineString;
import org.locationtech.jts.linearref.LinearLocation;
import org.locationtech.jts.linearref.LocationIndexedLine;
import org.opentripplanner.common.geometry.GeometryUtils;
import org.opentripplanner.common.geometry.SphericalDistanceLibrary;
import org.opentripplanner.common.model.P2;
import org.opentripplanner.routing.core.TraverseMode;
import org.opentripplanner.routing.core.TraverseModeSet;
import org.opentripplanner.routing.edgetype.AreaEdge;
import org.opentripplanner.routing.edgetype.StreetEdge;
import org.opentripplanner.routing.graph.Edge;
import org.opentripplanner.routing.graph.Graph;
import org.opentripplanner.routing.graph.Vertex;
import org.opentripplanner.routing.vertextype.SplitterVertex;
import org.opentripplanner.routing.vertextype.StreetVertex;
import org.opentripplanner.routing.vertextype.TemporarySplitterVertex;
import org.opentripplanner.util.OTPFeature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.function.BiFunction;
import java.util.stream.Collectors;
/**
* This class links transit stops to streets by splitting the streets (unless the stop is extremely
* close to the street intersection).
*
* It is intended to eventually completely replace the existing stop linking code, which had been
* through so many revisions and adaptations to different street and turn representations that it
* was very glitchy. This new code is also intended to be deterministic in linking to streets,
* independent of the order in which the JVM decides to iterate over Maps and even in the presence
* of points that are exactly halfway between multiple candidate linking points.
*
* It would be wise to keep this new incarnation of the linking code relatively simple, considering
* what happened before.
*
* See discussion in pull request #1922, follow up issue #1934, and the original issue calling for
* replacement of the stop linker, #1305.
*/
public class VertexLinker {
private static final Logger LOG = LoggerFactory.getLogger(VertexLinker.class);
/**
* Spatial index of StreetEdges in the graph.
*/
private final StreetSpatialIndex streetSpatialIndex = new StreetSpatialIndex();
private final Graph graph;
/**
* if there are two ways and the distances to them differ by less than this value, we link to both
* of them
*/
private static final double DUPLICATE_WAY_EPSILON_METERS = 0.001;
private static final int INITIAL_SEARCH_RADIUS_METERS = 100;
private static final int MAX_SEARCH_RADIUS_METERS = 1000;
private static final GeometryFactory GEOMETRY_FACTORY = GeometryUtils.getGeometryFactory();
// TODO Temporary code until we refactor WalkableAreaBuilder (#3152)
private Boolean addExtraEdgesToAreas = false;
/**
* Construct a new VertexLinker.
* NOTE: Only one VertexLinker should be active on a graph at any given time.
*/
public VertexLinker(Graph graph) {
for (StreetEdge se : graph.getEdgesOfType(StreetEdge.class) ) {
streetSpatialIndex.insert(se.getGeometry(), se, Scope.PERMANENT);
}
this.graph = graph;
}
public void linkVertexPermanently(
Vertex vertex,
TraverseModeSet traverseModes,
LinkingDirection direction,
BiFunction> edgeFunction
) {
link(
vertex,
traverseModes,
direction,
Scope.PERMANENT,
edgeFunction
);
}
public DisposableEdgeCollection linkVertexForRealTime(
Vertex vertex,
TraverseModeSet traverseModes,
LinkingDirection direction,
BiFunction> edgeFunction
) {
return link(
vertex,
traverseModes,
direction,
Scope.REALTIME,
edgeFunction
);
}
public DisposableEdgeCollection linkVertexForRequest(
Vertex vertex,
TraverseModeSet traverseModes,
LinkingDirection direction,
BiFunction> edgeFunction
) {
return link(
vertex,
traverseModes,
direction,
Scope.REQUEST,
edgeFunction
);
}
public void removeEdgeFromIndex(Edge edge, Scope scope) {
// Edges without geometry will not have been added to the index in the first place
if (edge.getGeometry() != null) {
streetSpatialIndex.remove(edge.getGeometry().getEnvelopeInternal(), edge, scope);
}
}
public void removePermanentEdgeFromIndex(Edge edge) {
removeEdgeFromIndex(edge, Scope.PERMANENT);
}
/**
* This method will link the provided vertex into the street graph. This may involve splitting an
* existing edge (if the scope is not PERMANENT, the existing edge will be kept).
*
* In OTP2 where the transit search can be quite fast, searching for a good linking point can be
* a significant fraction of response time. Hannes Junnila has reported >70% speedups in searches
* by making the search radius smaller. Therefore we use an expanding-envelope search, which is
* more efficient in dense areas.
*
* @param vertex Vertex to be linked into the street graph
* @param traverseModes Only street edges allowing one of these modes will be linked
* @param direction The direction of the new edges to be created
* @param scope The scope of the split
* @param edgeFunction How the provided vertex should be linked into the street graph
*
* @return A DisposableEdgeCollection with edges created by this method. It is the caller's
* responsibility to call the dispose method on this object when the edges are no longer needed.
*/
private DisposableEdgeCollection link(
Vertex vertex,
TraverseModeSet traverseModes,
LinkingDirection direction,
Scope scope,
BiFunction> edgeFunction
) {
DisposableEdgeCollection tempEdges = (scope != Scope.PERMANENT)
? new DisposableEdgeCollection(graph, scope)
: null;
try {
Set streetVertices = linkToStreetEdges(vertex,
traverseModes,
direction,
scope,
INITIAL_SEARCH_RADIUS_METERS,
tempEdges
);
if (streetVertices.isEmpty()) {
streetVertices = linkToStreetEdges(vertex,
traverseModes,
direction,
scope,
MAX_SEARCH_RADIUS_METERS,
tempEdges
);
}
for (StreetVertex streetVertex : streetVertices) {
List edges = edgeFunction.apply(vertex, streetVertex);
if (tempEdges != null) {
for (Edge edge : edges) {
tempEdges.addEdge(edge);
}
}
}
} catch (Exception e){
if (tempEdges != null) {
tempEdges.disposeEdges();
}
throw e;
}
return tempEdges;
}
private Set linkToStreetEdges(
Vertex vertex,
TraverseModeSet traverseModes,
LinkingDirection direction,
Scope scope,
int radiusMeters,
DisposableEdgeCollection tempEdges
) {
final double radiusDeg = SphericalDistanceLibrary.metersToDegrees(radiusMeters);
Envelope env = new Envelope(vertex.getCoordinate());
// Perform a simple local equirectangular projection, so distances are expressed in degrees latitude.
final double xscale = Math.cos(vertex.getLat() * Math.PI / 180);
// Expand more in the longitude direction than the latitude direction to account for converging meridians.
env.expandBy(radiusDeg / xscale, radiusDeg);
// Perform several transformations at once on the edges returned by the index. Only consider
// street edges traversable by at least one of the given modes and are still present in the
// graph. Calculate a distance to each of those edges, and keep only the ones within the search
// radius.
List> candidateEdges = streetSpatialIndex
.query(env, scope)
.filter(StreetEdge.class::isInstance)
.map(StreetEdge.class::cast)
.filter(e -> e.canTraverse(traverseModes) && edgeReachableFromGraph(e))
.map(e -> new DistanceTo<>(e, distance(vertex, e, xscale)))
.filter(ead -> ead.distanceDegreesLat < radiusDeg)
.collect(Collectors.toList());
if (candidateEdges.isEmpty()) { return Set.of(); }
Set> closesEdges = getClosestEdgesPerMode(
traverseModes,
candidateEdges
);
return closesEdges.stream()
.map(ce -> link(vertex, ce.item, xscale, scope, direction, tempEdges))
.collect(Collectors.toSet());
}
/**
* We need to get the closest edges per mode to be sure that we are linking to edges traversable
* by all the specified modes. We use a set here to avoid duplicates in the case that edges
* are traversable by more than one of the modes specified.
*/
private Set> getClosestEdgesPerMode(
TraverseModeSet traverseModeSet,
List> candidateEdges
) {
final double DUPLICATE_WAY_EPSILON_DEGREES = SphericalDistanceLibrary.metersToDegrees(
DUPLICATE_WAY_EPSILON_METERS
);
// The following logic has gone through several different versions using different approaches.
// The core idea is to find all edges that are roughly the same distance from the given vertex, which will
// catch things like superimposed edges going in opposite directions.
// First, all edges within DUPLICATE_WAY_EPSILON_METERS of of the best distance were selected.
// More recently, the edges were sorted in order of increasing distance, and all edges in the list were selected
// up to the point where a distance increase of DUPLICATE_WAY_EPSILON_DEGREES from one edge to the next.
// This was in response to concerns about arbitrary cutoff distances: at any distance, it's always possible
// one half of a dual carriageway (or any other pair of edges in opposite directions) will be caught and the
// other half lost. It seems like this was based on some incorrect premises about floating point calculations
// being non-deterministic.
Set> closesEdges = new HashSet<>();
for (TraverseMode mode : traverseModeSet.getModes()) {
TraverseModeSet modeSet = new TraverseModeSet(mode);
// There is at least one appropriate edge within range.
var candidateEdgesForMode =
candidateEdges.stream().filter(e -> e.item.canTraverse(modeSet)).collect(Collectors.toList());
if (candidateEdgesForMode.isEmpty()) { continue; }
double closestDistance = candidateEdgesForMode.stream()
.mapToDouble(ce -> ce.distanceDegreesLat)
.min()
.getAsDouble();
// Because this is a set, each instance of DistanceTo will only be added once
closesEdges.addAll(candidateEdges
.stream()
.filter(ce -> ce.distanceDegreesLat <= closestDistance + DUPLICATE_WAY_EPSILON_DEGREES)
.collect(Collectors.toSet()));
}
return closesEdges;
}
/**
* While in destructive splitting mode (during graph construction rather than handling routing
* requests), we remove edges that have been split and may then re-split the resulting segments
* recursively, so parts of them are also removed. Newly created edge fragments are added to the
* spatial index; the edges that were split are removed (disconnected) from the graph but were
* previously not removed from the spatial index, so for all subsequent splitting operations we
* had to check whether any edge coming out of the spatial index had been "soft deleted".
*
* I believe this was compensating for the fact that STRTrees are optimized at construction and
* read-only. That restriction no longer applies since we've been using our own hash grid spatial
* index instead of the STRTree. So rather than filtering out soft deleted edges, this is now an
* assertion that the system behaves as intended, and will log an error if the spatial index is
* returning edges that have been disconnected from the graph.
*/
private static boolean edgeReachableFromGraph(Edge edge) {
boolean edgeReachableFromGraph = edge.getToVertex().getIncoming().contains(edge);
if (!edgeReachableFromGraph) {
LOG.error(
"Edge returned from spatial index is no longer reachable from graph. That is not expected.");
}
return edgeReachableFromGraph;
}
/** Split the edge if necessary return the closest vertex */
private StreetVertex link(
Vertex vertex,
StreetEdge edge,
double xScale,
Scope scope,
LinkingDirection direction,
DisposableEdgeCollection tempEdges
) {
// TODO: we've already built this line string, we should save it
LineString orig = edge.getGeometry();
LineString transformed = equirectangularProject(orig, xScale);
LocationIndexedLine il = new LocationIndexedLine(transformed);
LinearLocation ll = il.project(new Coordinate(vertex.getLon() * xScale, vertex.getLat()));
double length = SphericalDistanceLibrary.length(orig);
// if we're very close to one end of the line or the other, or endwise, don't bother to split,
// cut to the chase and link directly
// We use a really tiny epsilon here because we only want points that actually snap to exactly the same location on the
// street to use the same vertices. Otherwise the order the stops are loaded in will affect where they are snapped.
if (ll.getSegmentIndex() == 0 && (ll.getSegmentFraction() < 1e-8 || ll.getSegmentFraction() * length < 0.1)) {
return (StreetVertex) edge.getFromVertex();
}
// -1 converts from count to index. Because of the fencepost problem, npoints - 1 is the "segment"
// past the last point
else if (ll.getSegmentIndex() == orig.getNumPoints() - 1) {
return (StreetVertex) edge.getToVertex();
}
// nPoints - 2: -1 to correct for index vs count, -1 to account for fencepost problem
else if (ll.getSegmentIndex() == orig.getNumPoints() - 2 && (
ll.getSegmentFraction() > 1 - 1e-8 || (1 - ll.getSegmentFraction()) * length < 0.1)
) {
return (StreetVertex) edge.getToVertex();
}
else {
// split the edge, get the split vertex
SplitterVertex v0 = split(edge, ll, scope, direction, tempEdges);
// If splitter vertex is part of area; link splittervertex to all other vertexes in area, this creates
// edges that were missed by WalkableAreaBuilder
// TODO Temporary code until we refactor the WalkableAreaBuilder (#3152)
if (scope == Scope.PERMANENT && this.addExtraEdgesToAreas && edge instanceof AreaEdge) {
((AreaEdge) edge).getArea().addVertex(v0);
}
// TODO Consider moving this code
if (OTPFeature.FlexRouting.isOn()) {
FlexLocationAdder.addFlexLocations(edge, v0, graph);
}
return v0;
}
}
/** projected distance from stop to edge, in latitude degrees */
private static double distance(Vertex tstop, StreetEdge edge, double xscale) {
// Despite the fact that we want to use a fast somewhat inaccurate projection, still use JTS library tools
// for the actual distance calculations.
LineString transformed = equirectangularProject(edge.getGeometry(), xscale);
return transformed.distance(GEOMETRY_FACTORY.createPoint(new Coordinate(tstop.getLon() * xscale,
tstop.getLat()
)));
}
/** project this linestring to an equirectangular projection */
private static LineString equirectangularProject(LineString geometry, double xScale) {
Coordinate[] coords = new Coordinate[geometry.getNumPoints()];
for (int i = 0; i < coords.length; i++) {
Coordinate c = geometry.getCoordinateN(i);
c = (Coordinate) c.clone();
c.x *= xScale;
coords[i] = c;
}
return GEOMETRY_FACTORY.createLineString(coords);
}
/**
* Split the street edge at the given fraction
*
* @param originalEdge to be split
* @param ll fraction at which to split the edge
* @param scope the scope of the split
* @param direction what direction to link the edges
* @param tempEdges collection of temporary edges
* @return Splitter vertex with added new edges
*/
private SplitterVertex split(
StreetEdge originalEdge,
LinearLocation ll,
Scope scope,
LinkingDirection direction,
DisposableEdgeCollection tempEdges
) {
LineString geometry = originalEdge.getGeometry();
// create the geometries
Coordinate splitPoint = ll.getCoordinate(geometry);
SplitterVertex v;
String uniqueSplitLabel = "split_" + graph.nextSplitNumber++;
if (scope != Scope.PERMANENT) {
TemporarySplitterVertex tsv = new TemporarySplitterVertex(uniqueSplitLabel,
splitPoint.x,
splitPoint.y,
originalEdge,
direction == LinkingDirection.OUTGOING
);
tsv.setWheelchairAccessible(originalEdge.isWheelchairAccessible());
v = tsv;
}
else {
v = new SplitterVertex(graph, uniqueSplitLabel, splitPoint.x, splitPoint.y, originalEdge);
}
// Split the 'edge' at 'v' in 2 new edges and connect these 2 edges to the
// existing vertices
P2 newEdges = scope == Scope.PERMANENT
? originalEdge.splitDestructively(v)
: originalEdge.splitNonDestructively(v, tempEdges, direction);
if (scope == Scope.REALTIME || scope == Scope.PERMANENT) {
// update indices of new edges
if (newEdges.first != null) {
streetSpatialIndex.insert(newEdges.first.getGeometry(), newEdges.first, scope);
}
if (newEdges.second != null) {
streetSpatialIndex.insert(newEdges.second.getGeometry(), newEdges.second, scope);
}
if (scope == Scope.PERMANENT) {
// remove original edge from the graph
originalEdge.getToVertex().removeIncoming(originalEdge);
originalEdge.getFromVertex().removeOutgoing(originalEdge);
// remove original edges from the spatial index
// This iterates over the entire rectangular envelope of the edge rather than the segments making it up.
// It will be inefficient for very long edges, but creating a new remove method mirroring the more efficient
// insert logic is not trivial and would require additional testing of the spatial index.
removeEdgeFromIndex(originalEdge, scope);
}
}
return v;
}
// TODO Temporary code until we refactor WalkableAreaBuilder (#3152)
public void setAddExtraEdgesToAreas(Boolean addExtraEdgesToAreas) {
this.addExtraEdgesToAreas = addExtraEdgesToAreas;
}
private static class DistanceTo {
T item;
// Possible optimization: store squared lat to skip thousands of sqrt operations
// However we're using JTS distance functions that probably won't allow us to skip the final sqrt call.
double distanceDegreesLat;
public DistanceTo(T item, double distanceDegreesLat) {
this.item = item;
this.distanceDegreesLat = distanceDegreesLat;
}
@Override
public boolean equals(Object o) {
if (this == o) { return true; }
if (o == null || getClass() != o.getClass()) { return false; }
DistanceTo that = (DistanceTo) o;
return Objects.equals(item, that.item);
}
@Override
public int hashCode() {
return Objects.hash(item);
}
}
}