//
// MERCnav.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 Mercator (MERC) type nav. This code was modified
* from the original FORTRAN code (nvxmerc.dlm) on the McIDAS system.
* It only supports latitude/longitude to line/element transformations (LL)
* and vice/versa. Transform to 'XYZ' not implemented.
* @see
* McIDAS Programmer's Manual
*
* @author Don Murray
*/
public final class MERCnav extends AREAnav
{
int iwest;
int leftlon;
double xrow;
double xcol;
double xlat1;
double xspace;
double xqlon;
double xblat;
double xblon;
/**
* Set up for the real math work. Must pass in the int array
* of the MERC nav 'codicil'.
*
* @param iparms the nav block from the image file
* @throws IllegalArgumentException
* if the nav block is not a MERC type.
*/
public MERCnav (int[] iparms)
throws IllegalArgumentException
{
if (iparms[0] != MERC )
throw new IllegalArgumentException("Invalid navigation type" +
iparms[0]);
xrow = iparms[1];
xcol = iparms[2];
xlat1 = McIDASUtil.integerLatLonToDouble(iparms[3]);
xspace = iparms[4]/1000.;
xqlon = McIDASUtil.integerLatLonToDouble(iparms[5]);
double r = iparms[6]/1000.;
iwest = iparms[9];
if (iwest >= 0) iwest = 1;
xblat = r * Math.cos(xlat1*DEGREES_TO_RADIANS)/xspace;
xblon = DEGREES_TO_RADIANS*r/xspace;
leftlon = (int) xqlon-180*iwest;
}
/** 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 xrlat, xrlon;
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 = xrow - imglinele[indexLine][point];
xedif = xcol - imglinele[indexEle][point];
xrlon = iwest*xedif/xblon;
xlon = xrlon+xqlon;
xrlat = Math.atan(Math.exp(xldif/xblat));
xlat = (xrlat/DEGREES_TO_RADIANS - 45.)*2.+xlat1;
if (xlon > (360.+leftlon) || xlon < leftlon)
{
latlon[indexLat][point] = Double.NaN;
latlon[indexLon][point] = Double.NaN;
}
else
{
latlon[indexLat][point] = xlat;
if (xlon > 180.) xlon = xlon - 360.;
if (xlon < -180.) xlon = xlon + 360.;
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;
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 = iwest*(xlon-xqlon);
if (xrlon > 180.) xrlon -= 360.;
if (xrlon < -180.) xrlon += 360.;
if (xlat >= 90.) xlat = 89.99;
if (xlat <= -90.) xlat = -89.99;
xrlat = ((xlat-xlat1)/2 + 45.)*DEGREES_TO_RADIANS;
if (xrlat <= 0.0)
{
linele[indexLine][point] = Double.NaN;
linele[indexEle][point] = Double.NaN;
}
else
{
linele[indexLine][point] =
xrow - xblat*Math.log(Math.tan(xrlat));
linele[indexEle][point] = xcol - xrlon*xblon;
}
} // end point loop
// Return in 'File' coordinates
return imageCoordToAreaCoord(linele, linele);
}
/** 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 float[][] toLatLon(float[][] linele)
{
double xldif;
double xedif;
double xlon;
double xlat;
double xrlon, xrlat;
int number = linele[0].length;
float[][] latlon = new float[2][number];
// Convert array to Image coordinates for computations
float[][] imglinele = areaCoordToImageCoord(linele);
for (int point=0; point < number; point++)
{
xldif = xrow - imglinele[indexLine][point];
xedif = xcol - imglinele[indexEle][point];
xrlon = iwest*xedif/xblon;
xlon = xrlon+xqlon;
xrlat = Math.atan(Math.exp(xldif/xblat));
xlat = (xrlat/DEGREES_TO_RADIANS - 45.)*2.+xlat1;
if (xlon > (360.+leftlon) || xlon < leftlon)
{
latlon[indexLat][point] = Float.NaN;
latlon[indexLon][point] = Float.NaN;
}
else
{
latlon[indexLat][point] = (float) xlat;
if (xlon > 180.f) xlon = xlon - 360.f;
if (xlon < -180.f) xlon = xlon + 360.f;
latlon[indexLon][point] = (float) ((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 float[][] toLinEle(float[][] latlon)
{
double xlon;
double xlat;
double xrlon, xrlat;
int number = latlon[0].length;
float[][] linele = new float[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 = iwest*(xlon-xqlon);
if (xrlon > 180.) xrlon -= 360.;
if (xrlon < -180.) xrlon += 360.;
if (xlat >= 90.) xlat = 89.99;
if (xlat <= -90.) xlat = -89.99;
xrlat = ((xlat-xlat1)/2 + 45.)*DEGREES_TO_RADIANS;
if (xrlat <= 0.0)
{
linele[indexLine][point] = Float.NaN;
linele[indexEle][point] = Float.NaN;
}
else
{
linele[indexLine][point] = (float)
(xrow - xblat*Math.log(Math.tan(xrlat)));
linele[indexEle][point] = (float) (xcol - xrlon*xblon);
}
} // end point loop
// Return in 'File' coordinates
return imageCoordToAreaCoord(linele, linele);
}
}
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