/* This program is free software: you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation, either version 3 of
the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
package org.opentripplanner.graph_builder.impl.ned;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import javax.media.jai.InterpolationBilinear;
import org.geotools.coverage.grid.GridCoverage2D;
import org.geotools.coverage.grid.Interpolator2D;
import org.geotools.geometry.DirectPosition2D;
import org.opengis.coverage.Coverage;
import org.opentripplanner.common.geometry.DistanceLibrary;
import org.opentripplanner.common.geometry.PackedCoordinateSequence;
import org.opentripplanner.common.geometry.SphericalDistanceLibrary;
import org.opentripplanner.common.pqueue.BinHeap;
import org.opentripplanner.graph_builder.annotation.ElevationFlattened;
import org.opentripplanner.graph_builder.impl.extra_elevation_data.ElevationPoint;
import org.opentripplanner.graph_builder.services.GraphBuilder;
import org.opentripplanner.graph_builder.services.ned.ElevationGridCoverageFactory;
import org.opentripplanner.routing.edgetype.StreetEdge;
import org.opentripplanner.routing.edgetype.StreetWithElevationEdge;
import org.opentripplanner.routing.graph.Edge;
import org.opentripplanner.routing.graph.Graph;
import org.opentripplanner.routing.graph.Vertex;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
/**
* {@link GraphBuilder} plugin that applies elevation data to street data that has already
* been loaded into a (@link Graph}, creating elevation profiles for each Street encountered
* in the Graph. Depending on the {@link ElevationGridCoverageFactory} specified
* this could be auto-downloaded and cached National Elevation Dataset (NED) raster data or
* a GeoTIFF file. The elevation profiles are stored as {@link PackedCoordinateSequence} objects,
* where each (x,y) pair represents one sample, with the x-coord representing the distance along
* the edge measured from the start, and the y-coord representing the sampled elevation at that
* point (both in meters).
*/
public class ElevationGraphBuilderImpl implements GraphBuilder {
private static final Logger log = LoggerFactory.getLogger(ElevationGraphBuilderImpl.class);
private ElevationGridCoverageFactory gridCoverageFactory;
private Coverage coverage;
/**
* The distance between samples in meters. Defaults to 10m, the approximate resolution of 1/3
* arc-second NED data.
*/
private double distanceBetweenSamplesM = 10;
private DistanceLibrary distanceLibrary = SphericalDistanceLibrary.getInstance();
public ElevationGraphBuilderImpl() { /* This makes me a "bean" */ };
public ElevationGraphBuilderImpl(ElevationGridCoverageFactory factory) {
this.setGridCoverageFactory(factory);
}
public List<String> provides() {
return Arrays.asList("elevation");
}
public List<String> getPrerequisites() {
return Arrays.asList("streets");
}
public void setGridCoverageFactory(ElevationGridCoverageFactory factory) {
gridCoverageFactory = factory;
}
public void setDistanceBetweenSamplesM(double distance) {
distanceBetweenSamplesM = distance;
}
@Override
public void buildGraph(Graph graph, HashMap<Class<?>, Object> extra) {
gridCoverageFactory.setGraph(graph);
Coverage gridCov = gridCoverageFactory.getGridCoverage();
// If gridCov is a GridCoverage2D, apply a bilinear interpolator. Otherwise, just use the
// coverage as is (note: UnifiedGridCoverages created by NEDGridCoverageFactoryImpl handle
// interpolation internally)
coverage = (gridCov instanceof GridCoverage2D) ? Interpolator2D.create(
(GridCoverage2D) gridCov, new InterpolationBilinear()) : gridCov;
log.info("setting street elevation profiles from NED data...");
List<StreetEdge> edgesWithElevation = new ArrayList<StreetEdge>();
int nProcessed = 0;
int nTotal = graph.countEdges();
for (Vertex gv : graph.getVertices()) {
for (Edge ee : gv.getOutgoing()) {
if (ee instanceof StreetWithElevationEdge) {
StreetWithElevationEdge edgeWithElevation = (StreetWithElevationEdge) ee;
processEdge(graph, edgeWithElevation);
if (edgeWithElevation.getElevationProfile() != null && !edgeWithElevation.isElevationFlattened()) {
edgesWithElevation.add(edgeWithElevation);
}
nProcessed += 1;
if (nProcessed % 50000 == 0)
log.info("set elevation on {}/{} edges", nProcessed, nTotal);
}
}
}
@SuppressWarnings("unchecked")
HashMap<Vertex, Double> extraElevation = (HashMap<Vertex, Double>) extra.get(ElevationPoint.class);
assignMissingElevations(graph, edgesWithElevation, extraElevation);
}
class ElevationRepairState {
/* This uses an intuitionist approach to elevation inspection */
public StreetEdge backEdge;
public ElevationRepairState backState;
public Vertex vertex;
public double distance;
public double initialElevation;
public ElevationRepairState(StreetEdge backEdge, ElevationRepairState backState,
Vertex vertex, double distance, double initialElevation) {
this.backEdge = backEdge;
this.backState = backState;
this.vertex = vertex;
this.distance = distance;
this.initialElevation = initialElevation;
}
}
/**
* Assign missing elevations by interpolating from nearby points with known
* elevation; also handle osm ele tags
*/
private void assignMissingElevations(Graph graph, List<StreetEdge> edgesWithElevation, HashMap<Vertex, Double> knownElevations) {
log.debug("Assigning missing elevations");
BinHeap<ElevationRepairState> pq = new BinHeap<ElevationRepairState>();
// elevation for each vertex (known or interpolated)
// knownElevations will be null if there are no ElevationPoints in the data
// for instance, with the Shapefile loader.)
HashMap<Vertex, Double> elevations;
if (knownElevations != null)
elevations = (HashMap<Vertex, Double>) knownElevations.clone();
else
elevations = new HashMap<Vertex, Double>();
HashSet<Vertex> closed = new HashSet<Vertex>();
// initialize queue with all vertices which already have known elevation
for (StreetEdge e : edgesWithElevation) {
PackedCoordinateSequence profile = e.getElevationProfile();
if (!elevations.containsKey(e.getFromVertex())) {
double firstElevation = profile.getOrdinate(0, 1);
ElevationRepairState state = new ElevationRepairState(null, null,
e.getFromVertex(), 0, firstElevation);
pq.insert(state, 0);
elevations.put(e.getFromVertex(), firstElevation);
}
if (!elevations.containsKey(e.getToVertex())) {
double lastElevation = profile.getOrdinate(profile.size() - 1, 1);
ElevationRepairState state = new ElevationRepairState(null, null, e.getToVertex(),
0, lastElevation);
pq.insert(state, 0);
elevations.put(e.getToVertex(), lastElevation);
}
}
// Grow an SPT outward from vertices with known elevations into regions where the
// elevation is not known. when a branch hits a region with known elevation, follow the
// back pointers through the region of unknown elevation, setting elevations via interpolation.
while (!pq.empty()) {
ElevationRepairState state = pq.extract_min();
if (closed.contains(state.vertex)) continue;
closed.add(state.vertex);
ElevationRepairState curState = state;
Vertex initialVertex = null;
while (curState != null) {
initialVertex = curState.vertex;
curState = curState.backState;
}
double bestDistance = Double.MAX_VALUE;
double bestElevation = 0;
for (Edge e : state.vertex.getOutgoing()) {
if (!(e instanceof StreetEdge)) {
continue;
}
StreetEdge edge = (StreetEdge) e;
Vertex tov = e.getToVertex();
if (tov == initialVertex)
continue;
Double elevation = elevations.get(tov);
if (elevation != null) {
double distance = e.getDistance();
if (distance < bestDistance) {
bestDistance = distance;
bestElevation = elevation;
}
} else {
// continue
ElevationRepairState newState = new ElevationRepairState(edge, state, tov,
e.getDistance() + state.distance, state.initialElevation);
pq.insert(newState, e.getDistance() + state.distance);
}
} // end loop over outgoing edges
for (Edge e : state.vertex.getIncoming()) {
if (!(e instanceof StreetEdge)) {
continue;
}
StreetEdge edge = (StreetEdge) e;
Vertex fromv = e.getFromVertex();
if (fromv == initialVertex)
continue;
Double elevation = elevations.get(fromv);
if (elevation != null) {
double distance = e.getDistance();
if (distance < bestDistance) {
bestDistance = distance;
bestElevation = elevation;
}
} else {
// continue
ElevationRepairState newState = new ElevationRepairState(edge, state, fromv,
e.getDistance() + state.distance, state.initialElevation);
pq.insert(newState, e.getDistance() + state.distance);
}
} // end loop over incoming edges
//limit elevation propagation to at max 2km; this prevents an infinite loop
//in the case of islands missing elevation (and some other cases)
if (bestDistance == Double.MAX_VALUE && state.distance > 2000) {
log.warn("While propagating elevations, hit 2km distance limit at " + state.vertex);
bestDistance = state.distance;
bestElevation = state.initialElevation;
}
if (bestDistance != Double.MAX_VALUE) {
// we have found a second vertex with elevation, so we can interpolate the elevation
// for this point
double totalDistance = bestDistance + state.distance;
// trace backwards, setting states as we go
while (true) {
// watch out for division by 0 here, which will propagate NaNs
// all the way out to edge lengths
if (totalDistance == 0)
elevations.put(state.vertex, bestElevation);
else {
double elevation = (bestElevation * state.distance +
state.initialElevation * bestDistance) / totalDistance;
elevations.put(state.vertex, elevation);
}
if (state.backState == null)
break;
bestDistance += state.backEdge.getDistance();
state = state.backState;
if (elevations.containsKey(state.vertex))
break;
}
}
} // end loop over states
// do actual assignments
for (Vertex v : graph.getVertices()) {
Double fromElevation = elevations.get(v);
for (Edge e : v.getOutgoing()) {
if (e instanceof StreetWithElevationEdge) {
StreetWithElevationEdge edge = ((StreetWithElevationEdge) e);
Double toElevation = elevations.get(edge.getToVertex());
if (fromElevation == null || toElevation == null) {
if (!edge.isElevationFlattened() && !edge.isSlopeOverride())
log.warn("Unexpectedly missing elevation for edge " + edge);
continue;
}
if (edge.getElevationProfile() != null && edge.getElevationProfile().size() > 2) {
continue;
}
Coordinate[] coords = new Coordinate[2];
coords[0] = new Coordinate(0, fromElevation);
coords[1] = new Coordinate(edge.getDistance(), toElevation);
PackedCoordinateSequence profile = new PackedCoordinateSequence.Double(coords);
if (edge.setElevationProfile(profile, true)) {
log.trace(graph.addBuilderAnnotation(new ElevationFlattened(edge)));
}
}
}
}
}
/**
* Processes a single street edge, creating and assigning the elevation profile.
*
* @param ee the street edge
* @param graph the graph (used only for error handling)
*/
private void processEdge(Graph graph, StreetWithElevationEdge ee) {
if (ee.getElevationProfile() != null) {
return; /* already set up */
}
Geometry g = ee.getGeometry();
Coordinate[] coords = g.getCoordinates();
List<Coordinate> coordList = new LinkedList<Coordinate>();
// calculate the total edge length in meters
double edgeLenM = 0;
for (int i = 0; i < coords.length - 1; i++) {
edgeLenM += distanceLibrary.distance(coords[i].y, coords[i].x, coords[i + 1].y,
coords[i + 1].x);
}
// initial sample (x = 0)
coordList.add(new Coordinate(0, getElevation(coords[0])));
// loop for edge-internal samples
for (double x = distanceBetweenSamplesM; x < edgeLenM; x += distanceBetweenSamplesM) {
// avoid final-segment samples less than half the distance between samples:
if (edgeLenM - x < distanceBetweenSamplesM / 2) {
break;
}
Coordinate internal = getPointAlongEdge(coords, edgeLenM, x / edgeLenM);
coordList.add(new Coordinate(x, getElevation(internal)));
}
// final sample (x = edge length)
coordList.add(new Coordinate(edgeLenM, getElevation(coords[coords.length - 1])));
// construct the PCS
Coordinate coordArr[] = new Coordinate[coordList.size()];
PackedCoordinateSequence elevPCS = new PackedCoordinateSequence.Double(
coordList.toArray(coordArr));
if(ee.setElevationProfile(elevPCS, false)) {
log.trace(graph.addBuilderAnnotation(new ElevationFlattened(ee)));
}
}
/**
* Returns a coordinate along a path located at a specific point indicated by the percentage of
* distance covered from start to end.
*
* @param coords the list of (x,y) coordinates that form the path
* @param length the total length of the path
* @param t the percentage (ranges from 0 to 1)
* @return the (x,y) coordinate at t
*/
public Coordinate getPointAlongEdge(Coordinate[] coords, double length, double t) {
double pctThrough = 0; // current percentage of the edge length traversed
// endpoints of current segment within edge:
double x1 = coords[0].x, y1 = coords[0].y, x2, y2;
for (int i = 1; i < coords.length - 1; i++) { // loop through inner points
Coordinate innerPt = coords[i];
x2 = innerPt.x;
y2 = innerPt.y;
// percentage of total edge length represented by current segment:
double pct = distanceLibrary .distance(y1, x1, y2, x2) / length;
if (pctThrough + pct > t) { // if current segment contains 't,' we're done
double pctAlongSeg = (t - pctThrough) / pct;
return new Coordinate(x1 + (pctAlongSeg * (x2 - x1)), y1
+ (pctAlongSeg * (y2 - y1)));
}
pctThrough += pct;
x1 = x2;
y1 = y2;
}
// handle the final segment separately
x2 = coords[coords.length - 1].x;
y2 = coords[coords.length - 1].y;
double pct = distanceLibrary.distance(y1, x1, y2, x2) / length;
double pctAlongSeg = (t - pctThrough) / pct;
return new Coordinate(x1 + (pctAlongSeg * (x2 - x1)), y1 + (pctAlongSeg * (y2 - y1)));
}
/**
* Method for retrieving the elevation at a given Coordinate.
*
* @param c the coordinate (NAD83)
* @return elevation in meters
*/
private double getElevation(Coordinate c) {
return getElevation(c.x, c.y);
}
/**
* Method for retrieving the elevation at a given (x, y) pair.
*
* @param x the query longitude (NAD83)
* @param y the query latitude (NAD83)
* @return elevation in meters
*/
private double getElevation(double x, double y) {
double values[] = new double[1];
try {
coverage.evaluate(new DirectPosition2D(x, y), values);
} catch (org.opengis.coverage.PointOutsideCoverageException e) {
// skip this for now
}
return values[0];
}
@Override
public void checkInputs() {
gridCoverageFactory.checkInputs();
}
}