ucar.nc2.dt.grid.gis.GridBoundariesExtractor Maven / Gradle / Ivy
The newest version!
/*
* Copyright (c) 1998-2018 John Caron and University Corporation for Atmospheric Research/Unidata
* See LICENSE for license information.
*/
package ucar.nc2.dt.grid.gis;
import java.util.ArrayList;
import java.util.List;
import ucar.nc2.dataset.CoordinateAxis1D;
import ucar.nc2.dataset.CoordinateAxis2D;
import ucar.nc2.dt.GridCoordSystem;
import ucar.nc2.dt.GridDataset;
import ucar.nc2.dt.GridDataset.Gridset;
import ucar.unidata.geoloc.LatLonPoint;
import ucar.unidata.geoloc.ProjectionImpl;
/**
*
* Provides methods for extracting the grid boundaries in standard GIS text formats: WKT and GeoJSON
*
* @author mhermida
*
*/
public final class GridBoundariesExtractor {
private GridDataset gridDataset;
private double minLon;
private double maxLon;
private double maxDiff;
private boolean crossesDateLine;
private GridBoundariesExtractor() {}
private GridBoundariesExtractor(GridDataset gridDataset) {
this.gridDataset = gridDataset;
}
/**
*
* Takes a GridDataset and returns the boundary for the first gridset in the dataset in as a polygon in WKT
*
*
* @return WKT
*/
public String getDatasetBoundariesWKT() {
StringBuilder polygonWKT = new StringBuilder("POLYGON((");
List polLons = new ArrayList<>();
List polLats = new ArrayList<>();
getLatLonsForPolygon(polLons, polLats);
// Build string from lists
// Crosses dateLine?
// Assuming grid cells don't extend more than 270 deg.
if ((maxLon > 0 && minLon < 0) && maxDiff > 270) {
// either crosses 0 or -180
crossesDateLine = true;
}
int nPoints = polLats.size();
for (int i = 0; i < nPoints; i++) {
double lon = polLons.get(i);
if (crossesDateLine && lon < 0)
lon += 360;
if (i < nPoints - 1)
polygonWKT.append(lon).append(" ").append(polLats.get(i)).append(",");
else
polygonWKT.append(lon).append(" ").append(polLats.get(i));
}
polygonWKT.append("))");
return polygonWKT.toString();
}
public String getDatasetBoundariesGeoJSON() {
StringBuilder polygonJSON = new StringBuilder("{\"type\":\"Polygon\", \"coordinates\":[ [ ");
List polLons = new ArrayList<>();
List polLats = new ArrayList<>();
getLatLonsForPolygon(polLons, polLats);
// Build string from lists
// Crosses dateLine?
// Assuming grid cells don't extend more than 270 deg.
if ((maxLon > 0 && minLon < 0) && maxDiff > 270) {
// either crosses 0 or -180
crossesDateLine = true;
}
int nPoints = polLats.size();
for (int i = 0; i < nPoints; i++) {
double lon = polLons.get(i);
if (crossesDateLine && lon < 0)
lon += 360;
if (i < nPoints - 1)
polygonJSON.append("[").append(lon).append(", ").append(polLats.get(i)).append("],");
else
polygonJSON.append("[").append(lon).append(", ").append(polLats.get(i)).append("]");
}
polygonJSON.append(" ] ]}");
return polygonJSON.toString();
}
private void getLatLonsForPolygon(List polLons, List polLats) {
Gridset gridset = gridDataset.getGridsets().get(0);
GridCoordSystem coordSystem = gridset.getGeoCoordSystem();
ProjectionImpl fromProj = coordSystem.getProjection();
coordSystem.getLatLonBoundingBox();
if (coordSystem.getYHorizAxis() instanceof CoordinateAxis1D
&& coordSystem.getXHorizAxis() instanceof CoordinateAxis1D) {
CoordinateAxis1D xAxis = (CoordinateAxis1D) coordSystem.getXHorizAxis();
CoordinateAxis1D yAxis = (CoordinateAxis1D) coordSystem.getYHorizAxis();
if (coordSystem.isGlobalLon()) {
double maxy = yAxis.getMaxValue();
double miny = yAxis.getMinValue();
polLons.add(0.0);
polLats.add(miny);
polLons.add(360.0);
polLats.add(miny);
polLons.add(360.0);
polLats.add(maxy);
polLons.add(0.0);
polLats.add(maxy);
polLons.add(0.0);
polLats.add(miny);
// polygonWKT.append("-180 "+ miny +", 180 "+ miny +", 180 "+ maxy +", -180 "+ maxy +", -180 "+ miny +"] ))");
// polygonWKT.append("0 "+ miny +", 360 "+ miny +", 360 "+ maxy +", 0 "+ maxy +", 0 "+ miny +"] ))");
// return polygonWKT.toString();
} else {
double[] xCoords = xAxis.getCoordValues();
double[] yCoords = yAxis.getCoordValues();
LatLonPoint prev = fromProj.projToLatLon(xCoords[0], yCoords[0]);
// Bottom edge
for (double x : xCoords) {
LatLonPoint point = fromProj.projToLatLon(x, yCoords[0]);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
// Right edge
for (double y : yCoords) {
LatLonPoint point = fromProj.projToLatLon(xCoords[xCoords.length - 1], y);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
// Top
for (int i = xCoords.length - 1; i >= 0; i--) {
LatLonPoint point = fromProj.projToLatLon(xCoords[i], yCoords[yCoords.length - 1]);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
// Left edge
for (int i = yCoords.length - 1; i >= 0; i--) {
LatLonPoint point = fromProj.projToLatLon(xCoords[0], yCoords[i]);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
}
} else if (coordSystem.getYHorizAxis() instanceof CoordinateAxis2D
&& coordSystem.getXHorizAxis() instanceof CoordinateAxis2D) {
// Get boundaries from 2d axis...
CoordinateAxis2D xAxis = (CoordinateAxis2D) coordSystem.getXHorizAxis();
CoordinateAxis2D yAxis = (CoordinateAxis2D) coordSystem.getYHorizAxis();
int[] xShape = xAxis.getShape();
int[] yShape = yAxis.getShape();
LatLonPoint prev = fromProj.projToLatLon(xAxis.getCoordValue(0, 0), yAxis.getCoordValue(0, 0));
for (int i = 0; i < xShape[0]; i++) {
double x = xAxis.getCoordValue(i, 0);
double y = yAxis.getCoordValue(i, 0);
LatLonPoint point = fromProj.projToLatLon(x, y);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
for (int i = 0; i < xShape[1]; i++) {
double x = xAxis.getCoordValue(xShape[0] - 1, i);
double y = yAxis.getCoordValue(xShape[0] - 1, i);
LatLonPoint point = fromProj.projToLatLon(x, y);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
for (int i = xShape[0] - 1; i >= 0; i--) {
double x = xAxis.getCoordValue(i, xShape[1] - 1);
double y = yAxis.getCoordValue(i, xShape[1] - 1);
LatLonPoint point = fromProj.projToLatLon(x, y);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
for (int i = xShape[1] - 1; i >= 0; i--) {
double x = xAxis.getCoordValue(0, i);
double y = yAxis.getCoordValue(0, i);
LatLonPoint point = fromProj.projToLatLon(x, y);
if (point.getLongitude() < minLon)
minLon = point.getLongitude();
if (point.getLongitude() > maxLon)
maxLon = point.getLongitude();
if (Math.abs(prev.getLongitude() - point.getLongitude()) > maxDiff)
maxDiff = Math.abs(prev.getLongitude() - point.getLongitude());
polLons.add(point.getLongitude());
polLats.add(point.getLatitude());
prev = point;
}
}
}
public static GridBoundariesExtractor valueOf(GridDataset gds) {
return new GridBoundariesExtractor(gds);
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy