ucar.nc2.iosp.grid.GridHorizCoordSys Maven / Gradle / Ivy
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The NetCDF-Java Library is a Java interface to NetCDF files,
as well as to many other types of scientific data formats.
/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.nc2.iosp.grid;
import ucar.ma2.Array;
import ucar.ma2.DataType;
import ucar.nc2.*;
import ucar.nc2.iosp.AbstractIOServiceProvider;
import ucar.nc2.constants.AxisType;
import ucar.nc2.constants._Coordinate;
import ucar.nc2.units.SimpleUnit;
import ucar.unidata.geoloc.*;
import ucar.unidata.geoloc.projection.*;
import ucar.unidata.geoloc.projection.sat.MSGnavigation;
import ucar.unidata.util.GaussianLatitudes;
import ucar.grid.GridTableLookup;
import ucar.grid.GridDefRecord;
import ucar.grib.grib2.Grib2GridTableLookup;
import ucar.grib.grib2.Grib2Tables;
import ucar.grib.grib1.Grib1GridTableLookup;
import ucar.unidata.util.StringUtil;
import java.util.*;
/**
* A horizontal coordinate system created from a GridDefRecord
*
*
* Note on "false_easting" and "fale_northing" projection parameters:
*
- false_easting(northing) = The value added to all x (y) values in the rectangular coordinates for a map projection.
* This value frequently is assigned to eliminate negative numbers.
* Expressed in the unit of measure identified in Planar Coordinate Units.
*
- We dont currently use, assuming that the x and y are just fine as negetive numbers.
*
* @author caron
*/
public class GridHorizCoordSys {
static private org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(GridHorizCoordSys.class);
/**
* GridVariables that have this GridHorizCoordSys
*/
Map
varHash = new HashMap(200);
/**
* List of GridVariable, sorted by product desc
*/
Map> productHash = new HashMap>(100);
/**
* lookup table
*/
private GridTableLookup lookup;
/**
* the grid definition object
*/
private GridDefRecord gds;
/**
* group for this system
*/
private Group g;
/**
* grid name, shape name and id
*/
private String grid_name, shape_name, id;
/**
* flags
*/
private boolean isLatLon = true, isGaussian = false;
/**
* GridVertCoordSys
*/
//HashMap vcsHash = new HashMap(30); // GridVertCoordSys
/**
* starting. incr values of prjection coordinates, used to generate the projection coordinate axis values
*/
private double startx, starty, incrx, incry;
/**
* projection
*/
private ProjectionImpl proj;
/**
* list of attributes
*/
private List attributes = new ArrayList();
/**
* Create a new GridHorizCoordSys with the grid definition and lookup
*
* @param gds grid definition
* @param lookup lookup table for names
* @param g Group for this coord system
*/
public GridHorizCoordSys(GridDefRecord gds, GridTableLookup lookup, Group g) {
this.gds = gds;
this.lookup = lookup;
this.g = g;
this.grid_name = AbstractIOServiceProvider.createValidNetcdfObjectName(
lookup.getGridName(gds));
this.shape_name = lookup.getShapeName(gds);
isLatLon = lookup.isLatLon(gds);
grid_name = StringUtil.replace(grid_name, ' ', "_");
id = (g == null)
? grid_name
: g.getName();
if (isLatLon && (lookup.getProjectionType(gds) == GridTableLookup.GaussianLatLon)) {
isGaussian = true;
double np = gds.getDouble(GridDefRecord.NP); // # lats between pole and equator (octet 26/27)
np = (Double.isNaN(np)) ? 90 : np;
//System.out.println( "np ="+np );
gds.addParam(GridDefRecord.DY, String.valueOf(np)); // fake - need to get actual gaussian calculation here
}
}
/**
* Get the ID
*
* @return the ID
*/
public String getID() {
return id;
} // unique within the file
/**
* Get the grid name
*
* @return the grid name
*/
public String getGridName() {
return grid_name;
} // used in CF-1 attributes
/**
* Get the group
*
* @return the group
*/
public Group getGroup() {
return g;
}
/**
* Is this a lat/lon grid
*
* @return true if is lat/lon
*/
public boolean isLatLon() {
return isLatLon;
}
/**
* Get the number of x points
*
* @return the number of x points
*/
public int getNx() {
return gds.getInt(GridDefRecord.NX);
}
/**
* Get the number of Y points
*
* @return the number of Y points
*/
public int getNy() {
return gds.getInt(GridDefRecord.NY);
}
/**
* Get the X spacing in kilometers
*
* @return the X spacing in kilometers
*/
public double getDxInKm() {
return getGridSpacingInKm(GridDefRecord.DX);
//return dx;
}
/**
* Get the Y spacing in kilometers
*
* @return the Y spacing in kilometers
*/
public double getDyInKm() {
return getGridSpacingInKm(GridDefRecord.DY);
//return dy;
}
/**
* Get the grid spacing in kilometers
* @param type
* @return the grid spacing in kilometers
*/
private double getGridSpacingInKm(String type) {
double value = gds.getDouble(type);
if (Double.isNaN(value)) return value;
String gridUnit = gds.getParam(GridDefRecord.GRID_UNITS);
SimpleUnit unit = null;
if (gridUnit == null || gridUnit.equals("")) {
unit = SimpleUnit.meterUnit;
} else {
unit = SimpleUnit.factory(gridUnit);
}
if (unit != null && SimpleUnit.isCompatible(unit.getUnitString(), "km")) {
value = unit.convertTo(value, SimpleUnit.kmUnit);
}
return value;
}
/**
* Add the dimensions associated with this coord sys to the netCDF file
*
* @param ncfile netCDF file to add to
*/
void addDimensionsToNetcdfFile(NetcdfFile ncfile) {
if (isLatLon) {
ncfile.addDimension(g, new Dimension("lat", gds.getInt(GridDefRecord.NY), true));
ncfile.addDimension(g, new Dimension("lon", gds.getInt(GridDefRecord.NX), true));
} else {
ncfile.addDimension(g, new Dimension("y", gds.getInt(GridDefRecord.NY), true));
ncfile.addDimension(g, new Dimension("x", gds.getInt(GridDefRecord.NX), true));
}
}
/**
* Add the variables to the netCDF file
*
* @param ncfile the netCDF file
*/
void addToNetcdfFile(NetcdfFile ncfile) {
if (isLatLon) {
double dy;
if (gds.getDouble(GridDefRecord.DY) == GridDefRecord.UNDEFINED) {
dy = setLatLonDxDy();
} else {
dy = (gds.getDouble(GridDefRecord.LA2) < gds.getDouble(GridDefRecord.LA1))
? -gds.getDouble(GridDefRecord.DY) : gds.getDouble(GridDefRecord.DY);
}
// lat
if (isGaussian) {
addGaussianLatAxis(ncfile, "lat", "degrees_north", "latitude coordinate", "latitude", AxisType.Lat);
} else {
addCoordAxis(ncfile, "lat", gds.getInt(GridDefRecord.NY), gds.getDouble(GridDefRecord.LA1), dy,
"degrees_north", "latitude coordinate", "latitude", AxisType.Lat);
}
// lon
addCoordAxis(ncfile, "lon", gds.getInt(GridDefRecord.NX), gds.getDouble(GridDefRecord.LO1), gds.getDouble(GridDefRecord.DX),
"degrees_east", "longitude coordinate", "longitude", AxisType.Lon);
// add dummy variable for lat/lon coord system
addCoordSystemVariable(ncfile, "latLonCoordSys", "time lat lon");
} else {
int projType = lookup.getProjectionType(gds);
if (makeProjection(ncfile, projType)) {
double[] yData, xData;
if (projType == GridTableLookup.RotatedLatLon) {
double dy = (gds.getDouble("La2") < gds.getDouble(GridDefRecord.LA1)
? -gds.getDouble(GridDefRecord.DY) : gds.getDouble(GridDefRecord.DY));
yData = addCoordAxis(ncfile, "y", gds.getInt(GridDefRecord.NY),
gds.getDouble(GridDefRecord.LA1), dy, "degrees",
"y coordinate of projection", "projection_y_coordinate", AxisType.GeoY);
xData = addCoordAxis(ncfile, "x", gds.getInt(GridDefRecord.NX),
gds.getDouble(GridDefRecord.LO1), gds.getDouble(GridDefRecord.DX), "degrees",
"x coordinate of projection", "projection_x_coordinate", AxisType.GeoX);
} else if (projType == GridTableLookup.Orthographic) {
yData = addCoordAxis(ncfile, "y", gds.getInt(GridDefRecord.NY), starty, incry, "km", // fake km - really pixel
"y coordinate of projection", "projection_y_coordinate", AxisType.GeoY); // dunno what the 3 is
xData = addCoordAxis(ncfile, "x", gds.getInt(GridDefRecord.NX), startx, incrx, "km",
"x coordinate of projection", "projection_x_coordinate", AxisType.GeoX);
} else if (projType == GridTableLookup.Curvilinear ) {
yData = null;
xData = null;
} else {
yData = addCoordAxis(ncfile, "y", gds.getInt(GridDefRecord.NY), starty, getDyInKm(), "km", "y coordinate of projection",
"projection_y_coordinate", AxisType.GeoY);
xData = addCoordAxis(ncfile, "x", gds.getInt(GridDefRecord.NX), startx, getDxInKm(), "km", "x coordinate of projection",
"projection_x_coordinate", AxisType.GeoX);
}
// optional 2D lat/lon
if (GridServiceProvider.addLatLon && (projType != GridTableLookup.Curvilinear))
addLatLon2D(ncfile, xData, yData);
}
}
}
// release memory after init
void empty() {
gds = null;
varHash = null;
productHash = null;
//vcsHash= null;
}
/**
* Add a coordinate axis
*
* @param ncfile the netCDF file to add to
* @param name name of the axis
* @param n number of points
* @param start starting value
* @param incr increment between points
* @param units units
* @param desc description
* @param standard_name standard name
* @param axis axis type
* @return the coordinate values
*/
private double[] addCoordAxis(NetcdfFile ncfile, String name, int n,
double start, double incr, String units,
String desc, String standard_name,
AxisType axis) {
// ncfile.addDimension(g, new Dimension(name, n, true));
Variable v = new Variable(ncfile, g, null, name);
v.setDataType(DataType.DOUBLE);
v.setDimensions(name);
// create the data
double[] data = new double[n];
for (int i = 0; i < n; i++) {
data[i] = start + incr * i;
}
Array dataArray = Array.factory(DataType.DOUBLE, new int[]{n}, data);
v.setCachedData(dataArray, false);
v.addAttribute(new Attribute("units", units));
v.addAttribute(new Attribute("long_name", desc));
v.addAttribute(new Attribute("standard_name", standard_name));
v.addAttribute(new Attribute("grid_spacing", incr + " " + units));
v.addAttribute(new Attribute(_Coordinate.AxisType, axis.toString()));
ncfile.addVariable(g, v);
return data;
}
/**
* Add a gaussian lat axis
*
* @param ncfile netCDF file to add to
* @param name name of the axis
* @param units units
* @param desc description
* @param standard_name standard name
* @param axis axis type
* @return the values
*/
private double[] addGaussianLatAxis(NetcdfFile ncfile, String name,
String units, String desc, String standard_name, AxisType axis) {
double np = gds.getDouble(GridDefRecord.NUMBERPARALLELS);
if (Double.isNaN(np)) np = gds.getDouble("Np");
if (Double.isNaN(np))
throw new IllegalArgumentException( "Gaussian Lat/Lon grid must have 'NumberParallels' or 'Np' (number of parallels) parameter");
double startLat = gds.getDouble(GridDefRecord.LA1);
double endLat = gds.getDouble(GridDefRecord.LA2);
int nlats = (int) (2 * np);
GaussianLatitudes gaussLats = new GaussianLatitudes(nlats);
int bestStartIndex = 0, bestEndIndex = 0;
double bestStartDiff = Double.MAX_VALUE;
double bestEndDiff = Double.MAX_VALUE;
for (int i = 0; i < nlats; i++) {
double diff = Math.abs(gaussLats.latd[i] - startLat);
if (diff < bestStartDiff) {
bestStartDiff = diff;
bestStartIndex = i;
}
diff = Math.abs(gaussLats.latd[i] - endLat);
if (diff < bestEndDiff) {
bestEndDiff = diff;
bestEndIndex = i;
}
}
assert Math.abs(bestEndIndex - bestStartIndex + 1) == gds.getInt(GridDefRecord.NY);
boolean goesUp = bestEndIndex > bestStartIndex;
Variable v = new Variable(ncfile, g, null, name);
v.setDataType(DataType.DOUBLE);
v.setDimensions(name);
// create the data
int n = (int) gds.getInt(GridDefRecord.NY);
int useIndex = bestStartIndex;
double[] data = new double[n];
double[] gaussw = new double[n];
for (int i = 0; i < n; i++) {
data[i] = gaussLats.latd[useIndex];
gaussw[i] = gaussLats.gaussw[useIndex];
if (goesUp) {
useIndex++;
} else {
useIndex--;
}
}
Array dataArray = Array.factory(DataType.DOUBLE, new int[]{n}, data);
v.setCachedData(dataArray, false);
v.addAttribute(new Attribute("units", units));
v.addAttribute(new Attribute("long_name", desc));
v.addAttribute(new Attribute("standard_name", standard_name));
v.addAttribute(new Attribute("weights", "gaussw"));
v.addAttribute(new Attribute(_Coordinate.AxisType, axis.toString()));
ncfile.addVariable(g, v);
v = new Variable(ncfile, g, null, "gaussw");
v.setDataType(DataType.DOUBLE);
v.setDimensions(name);
v.addAttribute(new Attribute("long_name", "gaussian weights (unnormalized)"));
dataArray = Array.factory(DataType.DOUBLE, new int[]{n}, gaussw);
v.setCachedData(dataArray, false);
ncfile.addVariable(g, v);
return data;
}
private void addLatLon2D(NetcdfFile ncfile, double[] xData, double[] yData) {
Variable latVar = new Variable(ncfile, g, null, "lat");
latVar.setDataType(DataType.DOUBLE);
latVar.setDimensions("y x");
latVar.addAttribute(new Attribute("units", "degrees_north"));
latVar.addAttribute(new Attribute("long_name", "latitude coordinate"));
latVar.addAttribute(new Attribute("standard_name", "latitude"));
latVar.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.Lat.toString()));
Variable lonVar = new Variable(ncfile, g, null, "lon");
lonVar.setDataType(DataType.DOUBLE);
lonVar.setDimensions("y x");
lonVar.addAttribute(new Attribute("units", "degrees_east"));
lonVar.addAttribute(new Attribute("long_name", "longitude coordinate"));
lonVar.addAttribute(new Attribute("standard_name", "longitude"));
lonVar.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.Lon.toString()));
int nx = xData.length;
int ny = yData.length;
// create the data
ProjectionPointImpl projPoint = new ProjectionPointImpl();
LatLonPointImpl latlonPoint = new LatLonPointImpl();
double[] latData = new double[nx * ny];
double[] lonData = new double[nx * ny];
for (int i = 0; i < ny; i++) {
for (int j = 0; j < nx; j++) {
projPoint.setLocation(xData[j], yData[i]);
proj.projToLatLon(projPoint, latlonPoint);
latData[i * nx + j] = latlonPoint.getLatitude();
lonData[i * nx + j] = latlonPoint.getLongitude();
}
}
Array latDataArray = Array.factory(DataType.DOUBLE, new int[]{ny, nx}, latData);
latVar.setCachedData(latDataArray, false);
Array lonDataArray = Array.factory(DataType.DOUBLE, new int[]{ny, nx}, lonData);
lonVar.setCachedData(lonDataArray, false);
ncfile.addVariable(g, latVar);
ncfile.addVariable(g, lonVar);
}
/**
* Make a projection and add it to the netCDF file
*
* @param ncfile netCDF file
* @return true if projection was added and coordinates need to be added, false means do nothing
*/
private boolean makeProjection(NetcdfFile ncfile, int projType) {
switch (projType) {
case GridTableLookup.RotatedLatLon:
makeRotatedLatLon(ncfile);
break;
case GridTableLookup.PolarStereographic:
makePS();
break;
case GridTableLookup.LambertConformal:
makeLC();
break;
case GridTableLookup.Mercator:
makeMercator();
break;
case GridTableLookup.Orthographic:
//makeSpaceViewOrOthographic();
makeMSGgeostationary();
break;
case GridTableLookup.Curvilinear:
makeCurvilinearAxis( ncfile);
break;
default:
throw new UnsupportedOperationException("unknown projection = "
+ gds.getInt(GridDefRecord.GRID_TYPE));
}
// dummy coordsys variable
Variable v = new Variable(ncfile, g, null, grid_name);
v.setDataType(DataType.CHAR);
v.setDimensions(""); // scalar
char[] data = new char[]{'d'};
Array dataArray = Array.factory(DataType.CHAR, new int[0], data);
v.setCachedData(dataArray, false);
for (Attribute att : attributes)
v.addAttribute(att);
// add CF Conventions attributes
v.addAttribute(new Attribute(GridCF.EARTH_SHAPE, shape_name));
// LOOK - spherical earth ??
double radius_spherical_earth = gds.getDouble(GridDefRecord.RADIUS_SPHERICAL_EARTH);
// have to check both because Grib1 and Grib2 used different names
if (Double.isNaN(radius_spherical_earth))
radius_spherical_earth = gds.getDouble("radius_spherical_earth");
if( ! Double.isNaN(radius_spherical_earth) ) {
// TODO: delete if no bug reports
//v.addAttribute(new Attribute("spherical_earth_radius_meters",
// new Double(radius_spherical_earth)));
v.addAttribute(new Attribute(GridCF.EARTH_RADIUS, new Double(radius_spherical_earth)));
} else { // oblate earth
double major_axis = gds.getDouble( GridDefRecord.MAJOR_AXIS_EARTH );
if (Double.isNaN( major_axis ))
major_axis = gds.getDouble("major_axis_earth");
double minor_axis = gds.getDouble( GridDefRecord.MINOR_AXIS_EARTH );
if (Double.isNaN(minor_axis))
minor_axis = gds.getDouble("minor_axis_earth");
if ( ! Double.isNaN ( major_axis ) && ! Double.isNaN ( minor_axis )) {
v.addAttribute(new Attribute(GridCF.SEMI_MAJOR_AXIS, new Double( major_axis )));
v.addAttribute(new Attribute(GridCF.SEMI_MINOR_AXIS, new Double( minor_axis )));
}
}
addGDSparams(v);
ncfile.addVariable(g, v);
return true;
}
/**
* Add the GDS params to the variable as attributes
*
* @param v the GDS params.
*/
private void addGDSparams(Variable v) {
// add all the gds parameters
List keyList = new ArrayList(gds.getKeys());
Collections.sort(keyList);
String pre =
((lookup instanceof Grib2GridTableLookup) ||
(lookup instanceof Grib1GridTableLookup)) ? "GRIB" : "GDS";
for (String key : keyList) {
String name =
AbstractIOServiceProvider.createValidNetcdfObjectName(pre + "_param_" + key);
String vals = gds.getParam(key);
try {
int vali = Integer.parseInt(vals);
if (key.equals(GridDefRecord.VECTOR_COMPONENT_FLAG)) {
String cf;
if (vali == 0) {
cf = Grib2Tables.VectorComponentFlag.easterlyNortherlyRelative.toString();
} else {
cf = Grib2Tables.VectorComponentFlag.gridRelative.toString();
}
v.addAttribute(new Attribute(name, cf));
} else {
v.addAttribute(new Attribute(name, new Integer(vali)));
}
} catch (Exception e) {
try {
double vald = Double.parseDouble(vals);
v.addAttribute(new Attribute(name, new Double(vald)));
} catch (Exception e2) {
v.addAttribute(new Attribute(name, vals));
}
}
}
}
/**
* Add coordinate system variable
*
* @param ncfile netCDF file
* @param name name of the variable
* @param dims dimensions
*/
private void addCoordSystemVariable(NetcdfFile ncfile, String name, String dims) {
Variable v = new Variable(ncfile, g, null, name);
v.setDataType(DataType.CHAR);
v.setDimensions(""); // scalar
Array dataArray = Array.factory(DataType.CHAR, new int[0], new char[]{'0'});
v.setCachedData(dataArray, false);
v.addAttribute(new Attribute(_Coordinate.Axes, dims));
if (isLatLon())
v.addAttribute(new Attribute(_Coordinate.Transforms, "")); // to make sure its identified as a Coordinate System Variable
else
v.addAttribute(new Attribute(_Coordinate.Transforms, getGridName()));
addGDSparams(v);
ncfile.addVariable(g, v);
}
/**
* Make a LambertConformalConic projection
*/
private void makeLC() {
// we have to project in order to find the origin
proj = new LambertConformal(
gds.getDouble(GridDefRecord.LATIN1), gds.getDouble(GridDefRecord.LOV),
gds.getDouble(GridDefRecord.LATIN1), gds.getDouble(GridDefRecord.LATIN2));
LatLonPointImpl startLL =
new LatLonPointImpl(gds.getDouble(GridDefRecord.LA1), gds.getDouble(GridDefRecord.LO1));
ProjectionPointImpl start = (ProjectionPointImpl) proj.latLonToProj(startLL);
startx = start.getX();
starty = start.getY();
if (Double.isNaN(getDxInKm())) {
setDxDy(startx, starty, proj);
}
if (GridServiceProvider.debugProj) {
System.out.println("GridHorizCoordSys.makeLC start at latlon " + startLL);
double Lo2 = gds.getDouble(GridDefRecord.LO2);
double La2 = gds.getDouble(GridDefRecord.LA2);
LatLonPointImpl endLL = new LatLonPointImpl(La2, Lo2);
System.out.println("GridHorizCoordSys.makeLC end at latlon " + endLL);
ProjectionPointImpl endPP = (ProjectionPointImpl) proj.latLonToProj(endLL);
System.out.println(" end at proj coord " + endPP);
double endx = startx + getNx() * getDxInKm();
double endy = starty + getNy() * getDyInKm();
System.out.println(" should be x=" + endx + " y=" + endy);
}
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME, "lambert_conformal_conic"));
if (gds.getDouble(GridDefRecord.LATIN1) == gds.getDouble(GridDefRecord.LATIN2)) {
attributes.add(new Attribute(GridCF.STANDARD_PARALLEL, new Double(gds.getDouble(GridDefRecord.LATIN1))));
} else {
double[] data = new double[]{gds.getDouble(GridDefRecord.LATIN1), gds.getDouble(GridDefRecord.LATIN2)};
attributes.add(new Attribute(GridCF.STANDARD_PARALLEL, Array.factory(DataType.DOUBLE, new int[]{2}, data)));
}
//attributes.add(new Attribute("longitude_of_central_meridian",
attributes.add(new Attribute(GridCF.LONGITUDE_OF_CENTRAL_MERIDIAN, new Double(gds.getDouble(GridDefRecord.LOV))));
//attributes.add(new Attribute("latitude_of_projection_origin",
attributes.add(new Attribute(GridCF.LATITUDE_OF_PROJECTION_ORIGIN, new Double(gds.getDouble(GridDefRecord.LATIN1))));
}
/**
* Make a PolarStereographic projection
*/
private void makePS() {
String nproj = gds.getParam(GridDefRecord.NPPROJ);
double latOrigin = (nproj == null || nproj.equalsIgnoreCase("true")) ? 90.0 : -90.0;
// Why the scale factor?. according to GRIB docs:
// "Grid lengths are in units of meters, at the 60 degree latitude circle nearest to the pole"
// since the scale factor at 60 degrees = k = 2*k0/(1+sin(60)) [Snyder,Working Manual p157]
// then to make scale = 1 at 60 degrees, k0 = (1+sin(60))/2 = .933
double scale;
double lad = gds.getDouble(GridDefRecord.LAD);
if (Double.isNaN(lad)) {
scale = .933;
} else {
scale = (1.0+Math.sin( Math.toRadians(lad) ))/2;
}
proj = new Stereographic(latOrigin, gds.getDouble(GridDefRecord.LOV), scale);
// we have to project in order to find the origin
ProjectionPointImpl start = (ProjectionPointImpl) proj.latLonToProj(
new LatLonPointImpl( gds.getDouble(GridDefRecord.LA1), gds.getDouble(GridDefRecord.LO1)));
startx = start.getX();
starty = start.getY();
if (Double.isNaN(getDxInKm()))
setDxDy(startx, starty, proj);
if (GridServiceProvider.debugProj) {
System.out.printf("starting proj coord %s lat/lon %s%n", start, proj.projToLatLon(start));
System.out.println(" should be LA1=" + gds.getDouble(GridDefRecord.LA1) + " l)1=" + gds.getDouble(GridDefRecord.LO1));
}
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME, "polar_stereographic"));
//attributes.add(new Attribute("longitude_of_projection_origin",
attributes.add(new Attribute(GridCF.LONGITUDE_OF_PROJECTION_ORIGIN, new Double(gds.getDouble(GridDefRecord.LOV))));
//attributes.add(new Attribute("straight_vertical_longitude_from_pole",
attributes.add(new Attribute( GridCF.STRAIGHT_VERTICAL_LONGITUDE_FROM_POLE, new Double(gds.getDouble(GridDefRecord.LOV))));
//attributes.add(new Attribute("scale_factor_at_projection_origin",
attributes.add(new Attribute(GridCF.SCALE_FACTOR_AT_PROJECTION_ORIGIN, new Double(scale)));
attributes.add(new Attribute(GridCF.LATITUDE_OF_PROJECTION_ORIGIN, new Double(latOrigin)));
}
/**
* Make a Mercator projection
*/
private void makeMercator() {
/**
* Construct a Mercator Projection.
* @param lon0 longitude of origin (degrees)
* @param par standard parallel (degrees). cylinder cuts earth at this latitude.
*/
double Latin = gds.getDouble(GridDefRecord.LAD);
// name depends on Grib version 1 or 2
if (Double.isNaN(Latin))
Latin = gds.getDouble(GridDefRecord.LATIN);
double Lo1 = gds.getDouble(GridDefRecord.LO1); //gds.Lo1;
double La1 = gds.getDouble(GridDefRecord.LA1); //gds.La1;
// put longitude origin at first point - doesnt actually matter
proj = new Mercator(Lo1, Latin);
// find out where
ProjectionPoint startP = proj.latLonToProj(
new LatLonPointImpl(La1, Lo1));
startx = startP.getX();
starty = startP.getY();
if (Double.isNaN(getDxInKm())) {
setDxDy(startx, starty, proj);
}
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME, "mercator"));
attributes.add(new Attribute(GridCF.STANDARD_PARALLEL, Latin));
attributes.add(new Attribute(GridCF.LONGITUDE_OF_PROJECTION_ORIGIN, Lo1));
if (GridServiceProvider.debugProj) {
double Lo2 = gds.getDouble(GridDefRecord.LO2);
if (Lo2 < Lo1) Lo2 += 360;
double La2 = gds.getDouble(GridDefRecord.LA2);
LatLonPointImpl endLL = new LatLonPointImpl(La2, Lo2);
System.out.println("GridHorizCoordSys.makeMercator: end at latlon= " +
endLL);
ProjectionPointImpl endPP = (ProjectionPointImpl) proj.latLonToProj(endLL);
System.out.println(" start at proj coord " +
new ProjectionPointImpl(startx, starty));
System.out.println(" end at proj coord " + endPP);
double endx = startx + (getNx() - 1) * getDxInKm();
double endy = starty + (getNy() - 1) * getDyInKm();
System.out.println(" should be x=" + endx + " y=" + endy);
}
}
// RotatedLatLon
private void makeRotatedLatLon(NetcdfFile ncfile) {
double splat = gds.getDouble(GridDefRecord.SPLAT);
double splon = gds.getDouble(GridDefRecord.SPLON);
double spangle = gds.getDouble(GridDefRecord.ROTATIONANGLE);
// Given projection coordinates, need LatLon coordinates
proj = new RotatedLatLon(splat, splon, spangle);
LatLonPoint startLL = proj.projToLatLon(
new ProjectionPointImpl(
gds.getDouble(GridDefRecord.LO1), gds.getDouble(GridDefRecord.LA1)));
startx = startLL.getLongitude();
starty = startLL.getLatitude();
addCoordSystemVariable(ncfile, "latLonCoordSys", "time y x");
// splat, splon, spangle
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME, "rotated_latlon_grib"));
attributes.add(new Attribute("grid_south_pole_latitude", new Double(splat)));
attributes.add(new Attribute("grid_south_pole_longitude", new Double(splon)));
attributes.add(new Attribute("grid_south_pole_angle", new Double(spangle)));
if (GridServiceProvider.debugProj) {
System.out.println("Location of pole of rotated grid:");
System.out.println("Lon=" + splon + ", Lat=" + splat);
System.out.println("Axial rotation about pole of rotated grid:" + spangle);
System.out.println("Location of LL in rotated grid:");
System.out.println("Lon=" + gds.getDouble(GridDefRecord.LO1) + ", " +
"Lat=" + gds.getDouble(GridDefRecord.LA1));
System.out.println("Location of LL in non-rotated grid:");
System.out.println("Lon=" + startx + ", Lat=" + starty);
double Lo2 = gds.getDouble(GridDefRecord.LO2);
double La2 = gds.getDouble(GridDefRecord.LA2);
System.out.println("Location of UR in rotated grid:");
System.out.println("Lon=" + Lo2 + ", Lat=" + La2);
System.out.println("Location of UR in non-rotated grid:");
LatLonPoint endUR = proj.projToLatLon(new ProjectionPointImpl(Lo2, La2));
System.out.println("Lon=" + endUR.getLongitude() + ", Lat=" + endUR.getLatitude());
double dy = (La2 < gds.getDouble(GridDefRecord.LA1)) ?
-gds.getDouble(GridDefRecord.DY) : gds.getDouble(GridDefRecord.DY);
double endx = gds.getDouble(GridDefRecord.LO1) + (getNx() - 1) * gds.getDouble(GridDefRecord.DX);
double endy = gds.getDouble(GridDefRecord.LA1) + (getNy() - 1) * dy;
System.out.println("End point rotated grid should be x=" +
endx + " y=" + endy);
}
}
/**
* Make a Space View Orthographic projection
*/
private void makeSpaceViewOrOthographic() {
double Lat0 = gds.getDouble(GridDefRecord.LAP); // sub-satellite point lat
double Lon0 = gds.getDouble(GridDefRecord.LOP); // sub-satellite point lon
double xp = gds.getDouble(GridDefRecord.XP); // sub-satellite point in grid lengths
double yp = gds.getDouble(GridDefRecord.YP);
double dx = gds.getDouble(GridDefRecord.DX); // apparent diameter in units of grid lengths
double dy = gds.getDouble(GridDefRecord.DY);
// have to check both names because Grib1 and Grib2 used different names
double major_axis = gds.getDouble(GridDefRecord.MAJOR_AXIS_EARTH); // km
if (Double.isNaN(major_axis) )
major_axis = gds.getDouble("major_axis_earth");
double minor_axis = gds.getDouble(GridDefRecord.MINOR_AXIS_EARTH); // km
if (Double.isNaN(minor_axis) )
minor_axis = gds.getDouble("minor_axis_earth");
// Nr = altitude of camera from center, in units of radius
double nr = gds.getDouble(GridDefRecord.NR) * 1e-6;
double apparentDiameter = 2 * Math.sqrt((nr - 1) / (nr + 1)); // apparent diameter, units of radius (see Snyder p 173)
// app diameter kmeters / app diameter grid lengths = m per grid length
double gridLengthX = major_axis * apparentDiameter / dx;
double gridLengthY = minor_axis * apparentDiameter / dy;
// have to add to both for consistency
gds.addParam(GridDefRecord.DX, String.valueOf(1000 * gridLengthX)); // meters
gds.addParam(GridDefRecord.DX, new Double(1000 * gridLengthX));
gds.addParam(GridDefRecord.DY, String.valueOf(1000 * gridLengthY)); // meters
gds.addParam(GridDefRecord.DY, new Double(1000 * gridLengthY));
startx = -gridLengthX * xp; // km
starty = -gridLengthY * yp;
double radius = Earth.getRadius() / 1000.0; // km
if (nr == 1111111111.0) { // LOOK: not sure how all ones will appear as a double, need example
proj = new Orthographic(Lat0, Lon0, radius);
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME, "orthographic"));
attributes.add(new Attribute(GridCF.LONGITUDE_OF_PROJECTION_ORIGIN,
new Double(Lon0)));
attributes.add(new Attribute(GridCF.LATITUDE_OF_PROJECTION_ORIGIN,
new Double(Lat0)));
} else { // "space view perspective"
double height = (nr - 1.0) * radius; // height = the height of the observing camera in km
proj = new VerticalPerspectiveView(Lat0, Lon0, radius, height);
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME,
"vertical_perspective"));
attributes.add(new Attribute(GridCF.LONGITUDE_OF_PROJECTION_ORIGIN,
new Double(Lon0)));
attributes.add(new Attribute(GridCF.LATITUDE_OF_PROJECTION_ORIGIN,
new Double(Lat0)));
attributes.add(new Attribute("height_above_earth",
new Double(height)));
}
if (GridServiceProvider.debugProj) {
double Lo2 = gds.getDouble(GridDefRecord.LO2) + 360.0;
double La2 = gds.getDouble(GridDefRecord.LA2);
LatLonPointImpl endLL = new LatLonPointImpl(La2, Lo2);
System.out.println(
"GridHorizCoordSys.makeOrthographic end at latlon "+ endLL);
ProjectionPointImpl endPP =
(ProjectionPointImpl) proj.latLonToProj(endLL);
System.out.println(" end at proj coord " + endPP);
double endx = startx + getNx() * getDxInKm();
double endy = starty + getNy() * getDyInKm();
System.out.println(" should be x=" + endx + " y=" + endy);
}
}
/**
* Make a Eumetsat MSG "Normalized Geostationary Projection" projection.
* Fake coordinates for now, then see if this can be generalized.
*
* from FM 92 GRIB-2 doc:
*
* Grid Definition Template 3.90: Space view perspective or orthographic
Octet Number(s) Contents
15 Shape of the earth (see Code Table 3.2)
16 Scale factor of radius of spherical earth
17-20 Scaled value of radius of spherical earth
21 Scale factor of major axis of oblate spheroid earth
22-25 Scaled value of major axis of oblate spheroid earth
26 Scale factor of minor axis of oblate spheroid earth
27-30 Scaled value of minor axis of oblate spheroid earth
31-34 Nx - number of points along X-axis (columns)
35-38 Ny - number of points along Y-axis (rows or lines)
39-42 Lap - latitude of sub-satellite point
43-46 Lop - longitude of sub-satellite point
47 Resolution and component flags (see Flag Table 3.3)
48-51 dx - apparent diameter of Earth in grid lengths, in X-direction
52-55 dy - apparent diameter of Earth in grid lengths, in Y-direction
56-59 Xp - X-coordinate of sub-satellite point (in units of 10-3 grid length expressed as an integer)
60-63 Yp - Y-coordinate of sub-satellite point (in units of 10-3 grid length expressed as an integer)
64 Scanning mode (flags - see Flag Table 3.4)
65-68 Orientation of the grid; i.e., the angle between the increasing Y-axis and the meridian of the sub-satellite point in the direction of increasing latitude (see Note 3)
69-72 Nr - altitude of the camera from the Earths centre, measured in units of the Earth (equatorial) radius multiplied by a scale factor of 10 6 (see Notes 4 and 5)
73-76 Xo - X-coordinate of origin of sector image
77-80 Yo - Y-coordinate of origin of sector image
Notes:
(1) It is assumed that the satellite is at its nominal position, i.e., it is looking directly at its sub-satellite point.
(2) Octets 69-72 shall be set to all ones (missing) to indicate the orthographic view (from infinite distance)
(3) It is the angle between the increasing Y-axis and the meridian 180E if the sub-satellite point is the North Pole; or the meridian 0 if the sub-satellite point is the South Pole.
(4) The apparent angular size of the Earth will be given by 2 * Arcsin (10^6 )/Nr).
(5) For orthographic view from infinite distance, the value of Nr should be encoded as missing (all bits set to 1).
(6) The horizontal and vertical angular resolutions of the sensor (Rx and Ry), needed for navigation equation, can be calculated from the following:
Rx = 2 * Arcsin (106 )/Nr)/ dx
Ry = 2 * Arcsin (106 )/Nr)/ dy
=======
from [email protected]
For products on a single pixel resolution grid, the scan angle is 83.84333 E-6 rad.
So dx = 2 * arcsin(10e6/Nr) / 83.84333 E-6 = 3622.30, which encoded to the nearest integer is 3622.
This is correctly encoded in our products.
For products on a 3x3 pixel resolution grid, the scan angle is 3 * 83.84333 E-6 rad = 251.52999 E-6 rad.
So dx = 2 * arcsin(10e6/Nr) / 251.52999 E-6 = 1207.43, which encoded to the nearest integer is 1207.
This is correctly encoded in our products.
Due to the elliptical shape of the earth, the calculation is a bit different in the y direction (Nr is in multiples of
the equatorial radius, but the tangent point is much closer to the polar radius from the earth's centre.
Approximating that the tangent point is actually at the polar radius from the earth's centre:
The sine of the angle subtended by the Earths centre and the tangent point on the equator as seen from the spacecraft
= Rp / (( Nr * Re) / 10^6) = (Rp * 10^6) / (Re * Nr)
The angle subtended by the Earth equator as seen by the spacecraft is, by symmetry twice the inverse sine above,
= 2 * arcsine ((Rp * 10^6) / (Re * Nr))
For products on a single pixel resolution grid, the scan angle is 83.84333 E-6 rad.
So dy = 2 * arcsine ((Rp * 10^6) / (Re * Nr)) / 83.84333 E-6 = 3610.06, which encoded to the nearest integer is 3610.
This is currently encoded in our products as 3568.
For products on a 3x3 pixel resolution grid, the scan angle is 3 * 83.84333 E-6 rad = 251.52999 E-6 rad.
So dy = 2 * arcsine ((Rp * 10^6) / (Re * Nr)) / 251.52999 E-6 = 1203.35, which encoded to the nearest integer is 1203.
This is currently encoded in our products as 1189.
As you can see the dx and dy values we are using will lead to an error of around 1% in the y direction.
I will ensure that the values are corrected to those explained here (3610 and 1203) as soon as possible.
*/
private void makeMSGgeostationary() {
double Lat0 = gds.getDouble(GridDefRecord.LAP); // sub-satellite point lat
double Lon0 = gds.getDouble(GridDefRecord.LOP); // sub-satellite point lon
int nx = gds.getInt(GridDefRecord.NX);
int ny = gds.getInt(GridDefRecord.NY);
int x_off = gds.getInt(GridDefRecord.XP); // sub-satellite point in grid lengths
int y_off = gds.getInt(GridDefRecord.YP);
double dx = gds.getDouble(GridDefRecord.DX); // apparent diameter of earth in units of grid lengths
double dy = gds.getDouble(GridDefRecord.DY);
// per Simon Eliot 1/18/2010, there is a bug in Eumetsat grib files,
// we need to "correct for ellipsoidal earth"
// (Note we should check who the originating center is
// "Originating_center" = "EUMETSAT Operation Centre" in the GRIB id (section 1))
// although AFAIK, eumetsat is only one using this projection.
if (dy < 2100) {
dx = 1207;
dy = 1203;
} else {
dx = 3622;
dy = 3610;
}
// have to check both names because Grib1 and Grib2 used different names
double major_axis = gds.getDouble(GridDefRecord.MAJOR_AXIS_EARTH); // m
if (Double.isNaN(major_axis))
major_axis = gds.getDouble("major_axis_earth");
double minor_axis = gds.getDouble(GridDefRecord.MINOR_AXIS_EARTH); // m
if (Double.isNaN(minor_axis))
minor_axis = gds.getDouble("minor_axis_earth");
// Nr = altitude of camera from center, in units of radius
double nr = gds.getDouble(GridDefRecord.NR) * 1e-6; // altitude of the camera from the Earths centre, measured in units of the Earth (equatorial) radius
// CFAC = 2^16 / {[2 * arcsine (10^6 / Nr)] / dx }
double as = 2 * Math.asin(1.0/nr);
double cfac = dx / as;
double lfac = dy / as;
// use km, so scale by the earth radius
double scale_factor = (nr - 1) * major_axis / 1000; // this sets the units of the projection x,y coords in km
double scale_x = scale_factor; // LOOK fake neg need scan value
double scale_y = -scale_factor; // LOOK fake neg need scan value
startx = scale_factor * (1 - x_off) / cfac;
starty = scale_factor * (y_off - ny) / lfac;
incrx = scale_factor/cfac;
incry = scale_factor/lfac;
attributes.add(new Attribute(GridCF.GRID_MAPPING_NAME, "MSGnavigation"));
attributes.add(new Attribute(GridCF.LONGITUDE_OF_PROJECTION_ORIGIN, new Double(Lon0)));
attributes.add(new Attribute(GridCF.LATITUDE_OF_PROJECTION_ORIGIN, new Double(Lat0)));
//attributes.add(new Attribute("semi_major_axis", new Double(major_axis)));
//attributes.add(new Attribute("semi_minor_axis", new Double(minor_axis)));
attributes.add(new Attribute("height_from_earth_center", new Double(nr * major_axis)));
attributes.add(new Attribute("scale_x", new Double(scale_x)));
attributes.add(new Attribute("scale_y", new Double(scale_y)));
proj = new MSGnavigation(Lat0, Lon0, major_axis, minor_axis, nr * major_axis, scale_x, scale_y);
if (GridServiceProvider.debugProj) {
double Lo2 = gds.getDouble(GridDefRecord.LO2) + 360.0;
double La2 = gds.getDouble(GridDefRecord.LA2);
LatLonPointImpl endLL = new LatLonPointImpl(La2, Lo2);
System.out.println("GridHorizCoordSys.makeMSGgeostationary end at latlon " + endLL);
ProjectionPointImpl endPP =(ProjectionPointImpl) proj.latLonToProj(endLL);
System.out.println(" end at proj coord " + endPP);
double endx = 1 + getNx();
double endy = 1 + getNy();
System.out.println(" should be x=" + endx + " y=" + endy);
}
}
// LOOK
/**
* CurvilinearAxis
*
* Make lat/lon axis from variables that start with Latitude/Longitude and then
* add the coordinates to the variables. This code is based on the ofs_atl files
* received from Rich Signell. This code is rigid because it expects coordinate names
* to start with Latitude/Longitude and other coordinate of depth.
* @param ncfile NetcdfFile
*/
private void makeCurvilinearAxis( NetcdfFile ncfile ) {
List vars = ncfile.getRootGroup().getVariables();
String latpp = null, lonpp = null, latU = null, lonU = null, latV = null, lonV = null;
// has to be done twice because there's no guarantee that the
// coordinate variables will be accessed first
List timeDimLL = new ArrayList();
List timeDimV = new ArrayList();
for( Variable var : vars ) {
if( var.getName().startsWith( "Latitude") ) {
// remove time dependency
int[] shape = var.getShape();
if (var.getRank() == 3 && shape[0] == 1) { // remove time dependencies - MAJOR KLUDGE
List dims = var.getDimensions();
if( ! timeDimLL.contains( dims.get( 0 ).getName() ))
timeDimLL.add( dims.get( 0 ).getName() );
dims.remove(0);
var.setDimensions(dims);
}
// add lat attributes
var.addAttribute(new Attribute("units", "degrees_north"));
var.addAttribute(new Attribute("long_name", "latitude coordinate"));
var.addAttribute(new Attribute("standard_name", "latitude"));
var.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.Lat.toString()));
if( var.getName().contains( "U_Wind_Component")) {
latU = var.getName();
} else if( var.getName().contains( "V_Wind_Component")) {
latV = var.getName();
} else {
latpp = var.getName();
}
} else if( var.getName().startsWith( "Longitude" )) {
// remove time dependency
int[] shape = var.getShape();
if (var.getRank() == 3 && shape[0] == 1) { // remove time dependencies - MAJOR KLUDGE
List dims = var.getDimensions();
if( ! timeDimLL.contains( dims.get( 0 ).getName() ))
timeDimLL.add( dims.get( 0 ).getName() );
dims.remove(0);
var.setDimensions(dims);
}
// add lon attributes
var.addAttribute(new Attribute("units", "degrees_east"));
var.addAttribute(new Attribute("long_name", "longitude coordinate"));
var.addAttribute(new Attribute("standard_name", "longitude"));
var.addAttribute(new Attribute(_Coordinate.AxisType, AxisType.Lon.toString()));
if( var.getName().contains( "U_Wind_Component")) {
lonU = var.getName();
} else if( var.getName().contains( "V_Wind_Component")) {
lonV = var.getName();
} else {
lonpp = var.getName();
}
}
}
// add coordinates attribute to variables
for( Variable var : vars ) {
List dims = var.getDimensions();
if( var.getName().startsWith( "U-component") ) {
var.addAttribute(new Attribute("coordinates", latU +" "+ lonU));
if( ! timeDimV.contains( dims.get( 0 ).getName() ))
timeDimV.add( dims.get( 0 ).getName() );
} else if( var.getName().startsWith( "V-component") ) {
var.addAttribute(new Attribute("coordinates", latV +" "+ lonV));
if( ! timeDimV.contains( dims.get( 0 ).getName() ))
timeDimV.add( dims.get( 0 ).getName() );
// rest of variables default to Pressure_Point
} else {
var.addAttribute(new Attribute("coordinates", latpp +" "+ lonpp));
if( ! timeDimV.contains( dims.get( 0 ).getName() ))
timeDimV.add( dims.get( 0 ).getName() );
}
}
/* remove Latitude/Longitude time dimension and variable if possible
for( String tdLL : timeDimLL) {
if( timeDimV.contains( tdLL ))
continue;
// else only used with Lat/Lon
ncfile.getRootGroup().removeDimension( tdLL );
ncfile.getRootGroup().removeVariable( tdLL );
} */
}
/**
* Calculate the dx and dy from startx, starty and projection.
*
* @param startx starting x projection point
* @param starty starting y projection point
* @param proj projection for transform
*/
private void setDxDy(double startx, double starty, ProjectionImpl proj) {
double Lo2 = gds.getDouble(GridDefRecord.LO2);
double La2 = gds.getDouble(GridDefRecord.LA2);
if (Double.isNaN(Lo2) || Double.isNaN(La2)) {
return;
}
LatLonPointImpl endLL = new LatLonPointImpl(La2, Lo2);
ProjectionPointImpl end =
(ProjectionPointImpl) proj.latLonToProj(endLL);
double dx = Math.abs(end.getX() - startx)
/ (gds.getInt(GridDefRecord.NX) - 1);
double dy = Math.abs(end.getY() - starty)
/ (gds.getInt(GridDefRecord.NY) - 1);
gds.addParam(GridDefRecord.DX, String.valueOf(dx));
gds.addParam(GridDefRecord.DY, String.valueOf(dy));
gds.addParam(GridDefRecord.GRID_UNITS, "km");
}
/**
* Calculate Dx Dy Lat Lon Grid
* Note: this assumes lo1 < lo2 and dx is positive going east
* @return dy double
*/
private double setLatLonDxDy() {
double lo1 = gds.getDouble(GridDefRecord.LO1);
double la1 = gds.getDouble(GridDefRecord.LA1);
double lo2 = gds.getDouble(GridDefRecord.LO2);
double la2 = gds.getDouble(GridDefRecord.LA2);
if (Double.isNaN(lo2) || Double.isNaN(la2)) {
return Double.NaN;
}
if (lo2 < lo1) lo2 += 360;
double dx = Math.abs(lo2 - lo1)
/ (gds.getInt(GridDefRecord.NX) - 1);
double dy = Math.abs(la2 - la1)
/ (gds.getInt(GridDefRecord.NY) - 1);
gds.addParam(GridDefRecord.DX, String.valueOf(dx));
gds.addParam(GridDefRecord.DY, String.valueOf(dy));
// in case someone checked on these before, we need to override
gds.addParam(GridDefRecord.DX, new Double(dx));
gds.addParam(GridDefRecord.DY, new Double(dy));
gds.addParam(GridDefRecord.GRID_UNITS, "degree");
return dy;
}
/**
* returns the gds for this hcs
* @return gds GridDefRecord
*/
public GridDefRecord getGds() {
return gds;
}
}