//
// LAMBnav.java
//
/*
This source file is part of the edu.wisc.ssec.mcidas package and is
Copyright (C) 1998 - 2017 by Tom Whittaker, Tommy Jasmin, Tom Rink,
Don Murray, James Kelly, Bill Hibbard, Dave Glowacki, Curtis Rueden
and others.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA
*/
package edu.wisc.ssec.mcidas;
/**
* Navigation class for Lambert Conformal (LAMB) type nav. This code was
* modified from the original FORTRAN code (nvxlamb.dlm) on the McIDAS system.
* It only supports latitude/longitude to line/element transformations (LL)
* and vice/versa. Transform to 'XYZ' not implemented.
* @see <A HREF="http://www.ssec.wisc.edu/mcidas/doc/prog_man.html">
* McIDAS Programmer's Manual</A>
*
* @author Don Murray
*/
public final class LAMBnav extends AREAnav
{
int iwest;
int ihem;
double xrow;
double xcol;
double xlat1;
double xlat2;
double xspace;
double xqlon;
double xblat;
double xfac;
double xpole;
/**
* Set up for the real math work. Must pass in the int array
* of the LAMB nav 'codicil'.
*
* @param iparms the nav block from the image file
* @throws IllegalArgumentException
* if the nav block is not a LAMB type.
*/
public LAMBnav (int[] iparms)
throws IllegalArgumentException
{
if (iparms[0] != LAMB )
throw new IllegalArgumentException("Invalid navigation type" +
iparms[0]);
xrow = iparms[1];
xcol = iparms[2];
int ipole = iparms[11];
if (ipole == 0) ipole = 900000;
ihem = 1;
if (ipole < 0) ihem = -1;
xpole = McIDASUtil.integerLatLonToDouble(ipole);
xlat1 = McIDASUtil.integerLatLonToDouble(iparms[3]);
xlat2 = McIDASUtil.integerLatLonToDouble(iparms[4]);
xlat1 = (90. - ihem*xlat1)*DEGREES_TO_RADIANS;
xlat2 = (90. - ihem*xlat2)*DEGREES_TO_RADIANS;
xspace = iparms[5]/1000.;
xqlon = McIDASUtil.integerLatLonToDouble(iparms[6]);
double r = iparms[7]/1000.;
iwest = iparms[10];
if (iwest >= 0) iwest = 1;
xfac = (Math.log(Math.sin(xlat1)) - Math.log(Math.sin(xlat2)))/
(Math.log(Math.tan(.5*xlat1)) - Math.log(Math.tan(.5*xlat2)));
xblat = r * Math.sin(xlat1)/
(xspace*xfac*Math.pow(Math.tan(xlat1*.5), xfac));
}
/** converts from satellite coordinates to latitude/longitude
*
* @param linele array of line/element pairs. Where
* linele[indexLine][] is a 'line' and
* linele[indexEle][] is an element. These are in
* 'file' coordinates (not "image" coordinates.)
*
* @return latlon[][] array of lat/long pairs. Output array is
* latlon[indexLat][] of latitudes and
* latlon[indexLon][] of longitudes.
*
*/
public double[][] toLatLon(double[][] linele)
{
double xldif;
double xedif;
double xlon;
double xlat;
double xrlon, radius;
int number = linele[0].length;
double[][] latlon = new double[2][number];
// Convert array to Image coordinates for computations
double[][] imglinele = areaCoordToImageCoord(linele);
for (int point=0; point < number; point++)
{
xldif = ihem*(imglinele[indexLine][point] - xrow)/xblat;
xedif = -ihem*(imglinele[indexEle][point] - xcol)/xblat;
xrlon = 0;
if (!(xldif == 0 && xedif == 0)) xrlon = Math.atan2(xedif, xldif);
xlon = ihem*xrlon/xfac/DEGREES_TO_RADIANS + xqlon;
xlon = (xlon+900.)%360. - 180.0;
radius = Math.sqrt(xldif*xldif + xedif*xedif);
if (Math.abs(radius) < 1.e-10)
xlat = ihem*90;
else
xlat = ihem*(90. - 2*Math.atan(
Math.exp(Math.log(radius)/xfac))/DEGREES_TO_RADIANS);
latlon[indexLat][point] = xlat;
latlon[indexLon][point] = (iwest == 1) ? -xlon : xlon;
} // end point for loop
return latlon;
}
/**
* toLinEle converts lat/long to satellite line/element
*
* @param latlon array of lat/long pairs. Where latlon[indexLat][]
* are latitudes and latlon[indexLon][] are longitudes.
*
* @return linele[][] array of line/element pairs. Where
* is an element. These are in 'file' coordinates
* (not "image" coordinates);
*/
public double[][] toLinEle(double[][] latlon)
{
double xlon;
double xlat;
double xrlon, xrlat, xclat;
int number = latlon[0].length;
double[][] linele = new double[2][number];
for (int point=0; point < number; point++)
{
xlat = latlon[indexLat][point];
// transform to McIDAS (west positive longitude) coordinates
xlon = (iwest == 1)
? -latlon[indexLon][point]
: latlon[indexLon][point];
xrlon = ihem*(xlon-xqlon);
xrlon = (xrlon+900.)%360. - 180.;
xrlon = xrlon*xfac*DEGREES_TO_RADIANS;
xclat = (90. - ihem*xlat)*DEGREES_TO_RADIANS*.5;
if (xclat == 0.0)
xrlat = 0.0;
else
xrlat = xblat*Math.pow(Math.tan(Math.abs(xclat)), xfac);
linele[indexLine][point] = xrow + ihem*(xrlat*Math.cos(xrlon));
linele[indexEle][point] = xcol - ihem*(xrlat*Math.sin(xrlon));
} // end point loop
// Return in 'File' coordinates
return imageCoordToAreaCoord(linele, linele);
}
}