com.bbn.openmap.proj
Class ProjMath

java.lang.Object
  com.bbn.openmap.proj.ProjMath

public final class ProjMath
extends java.lang.Object

Math functions used by projection code.

Field Summary

static double	DATELINE_D Dateline longitude in radians.
static double	DATELINE_DEG_D Dateline longitude in degrees.
static float	DATELINE_F Dateline longitude in radians.
static double	LON_RANGE_D Longitude range in radians.
static double	LON_RANGE_DEG_D Longitude range in degrees.
static float	LON_RANGE_F Longitude range in radians.
static double	NORTH_POLE_D North pole latitude in radians.
static double	NORTH_POLE_DEG_D North pole latitude in degrees.
static float	NORTH_POLE_F North pole latitude in radians.
static double	SOUTH_POLE_D South pole latitude in radians.
static double	SOUTH_POLE_DEG_D South pole latitude in degrees.
static float	SOUTH_POLE_F South pole latitude in radians.

Method Summary

static double[]	arrayDegToRad(double[] degs) Converts an array of decimal degrees double lat/lons to double radians in place.
static float[]	arrayDegToRad(float[] degs) Converts an array of decimal degrees float lat/lons to float radians in place.
static double[]	arrayRadToDeg(double[] rads) Converts an array of radian double lat/lons to decimal degrees in place.
static float[]	arrayRadToDeg(float[] rads) Converts an array of radian float lat/lons to decimal degrees in place.
static long	DEG_TO_SC(double deg) Convert between decimal degrees and scoords.
static double	degToRad(double deg) Convert degrees to radians.
static float	degToRad(float deg) Convert degrees to radians.
static double	distance(double[] radianCoords) Cumulative distance calculated between coords.
static float	geocentric_latitude(float lat, float lon) Deprecated. use geocentricLatitude instead.
static float	geocentricLatitude(float lat, float flat) Calculate the geocentric latitude given a geographic latitude.
static float	geographic_latitude(float lat, float lon) Deprecated. use geographicLoatitude instead.
static float	geographicLatitude(float lat, float flat) Calculate the geographic latitude given a geocentric latitude.
static double[]	getProjectionScreenOutlineCoords(Projection sourceMapProjection) Walks around the perimeter of the sourceMapProjection and returns the lat/lon coords of the outline.
static java.awt.geom.Rectangle2D	getRatioBox(Projection proj, java.awt.geom.Point2D pt1, java.awt.geom.Point2D pt2, boolean zoomOnCenter) Given a projection to match against and the starting point of a box (pt1), look at pt2 to see if it represents the ratio of the projection map size.
static java.awt.Point	getRatioPoint(Projection proj, java.awt.Point pt1, java.awt.Point pt2) Given a projection and the starting point of a box (pt1), look at pt2 to see if it represents the ratio of the projection map size.
protected static float	getScale(java.awt.geom.Point2D ll1, java.awt.geom.Point2D ll2, java.awt.geom.Point2D point1, java.awt.geom.Point2D point2, Projection projection) Given a couple of points representing a bounding box, find out what the scale should be in order to make those points appear at the corners of the projection.
static float	getScale(java.awt.geom.Point2D ll1, java.awt.geom.Point2D ll2, Projection projection) Given a couple of points representing a bounding box, find out what the scale should be in order to make those points appear at the corners of the projection.
static float	getScale(java.awt.Point point1, java.awt.Point point2, Projection projection) Given a couple of points representing a bounding box, find out what the scale should be in order to make those points appear at the corners of the projection.
static float	getScaleFromProjected(java.awt.geom.Point2D point1, java.awt.geom.Point2D point2, Projection projection) Given a couple of points representing a bounding box of projected coordinates, find out what the scale should be in order to make those points appear at the corners of the projection, with the intention that the bounding box will then fill the projected space.
static int	hashLatLon(float lat, float lon) Generate a hashCode value for a lat/lon pair.
static boolean	isCrossingDateline(double leftLon, double rightLon, float projScale) Generic test for seeing if an left longitude value and a right longitude value seem to constitute crossing the dateline.
static boolean	isVisible(Projection sourceMapProjection, java.awt.geom.Point2D llp) Returns true if the Point is visible on the provided projection.
static float	lonDistance(float lon1, float lon2) Calculate the shortest arc distance between two lons.
static double	normalize_latitude(double lat, double epsilon) Deprecated. use normalizeLatitude instead.
static float	normalize_latitude(float lat, float epsilon) Deprecated. use normalizeLatitude instead.
static double	normalizeLatitude(double lat, double epsilon) Normalizes radian latitude.
static float	normalizeLatitude(float lat, float epsilon) Normalizes radian latitude.
static double	qint(double x) Rounds the quantity away from 0.
static double	radToDeg(double rad) Convert radians to degrees.
static float	radToDeg(float rad) Convert radians to degrees.
static double	roundAdjust(double x) rounds the quantity away from 0.
static double	SC_TO_DEG(int sc) Convert between decimal degrees and scoords.
static float	sphericalUnitsToDeg(float u, float uCircumference) Converts units (km, nm, miles, etc) to decimal degrees for a spherical planet.
static float	sphericalUnitsToRad(float u, float uCircumference) Converts units (km, nm, miles, etc) to arc radians for a spherical planet.
static double	wrap_longitude(double lon) Deprecated. use wrapLongitude instead.
static float	wrap_longitude(float lon) Deprecated. use wrapLongitde instead.
static double	wrapLongitude(double lon) Sets radian longitude to something sane.
static float	wrapLongitude(float lon) Sets radian longitude to something sane.
static double	wrapLongitudeDeg(double lon) Sets degree longitude to something sane.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NORTH_POLE_F

public static final transient float NORTH_POLE_F

North pole latitude in radians.

See Also:

Constant Field Values

SOUTH_POLE_F

public static final transient float SOUTH_POLE_F

South pole latitude in radians.

See Also:

Constant Field Values

NORTH_POLE_D

public static final transient double NORTH_POLE_D

North pole latitude in radians.

See Also:

Constant Field Values

NORTH_POLE_DEG_D

public static final transient double NORTH_POLE_DEG_D

North pole latitude in degrees.

See Also:

Constant Field Values

SOUTH_POLE_D

public static final transient double SOUTH_POLE_D

South pole latitude in radians.

See Also:

Constant Field Values

SOUTH_POLE_DEG_D

public static final transient double SOUTH_POLE_DEG_D

South pole latitude in degrees.

See Also:

Constant Field Values

DATELINE_F

public static final transient float DATELINE_F

Dateline longitude in radians.

See Also:

Constant Field Values

DATELINE_D

public static final transient double DATELINE_D

Dateline longitude in radians.

See Also:

Constant Field Values

DATELINE_DEG_D

public static final transient double DATELINE_DEG_D

Dateline longitude in degrees.

See Also:

Constant Field Values

LON_RANGE_F

public static final transient float LON_RANGE_F

Longitude range in radians.

See Also:

Constant Field Values

LON_RANGE_D

public static final transient double LON_RANGE_D

Longitude range in radians.

See Also:

Constant Field Values

LON_RANGE_DEG_D

public static final transient double LON_RANGE_DEG_D

Longitude range in degrees.

See Also:

Constant Field Values

Method Detail

roundAdjust

public static final double roundAdjust(double x)

rounds the quantity away from 0.

Parameters:

x - in value

Returns:

double

See Also:

qint(double)

qint

public static final double qint(double x)

Rounds the quantity away from 0.

Parameters:

x - value

Returns:

double

lonDistance

public static final float lonDistance(float lon1,
                                      float lon2)

Calculate the shortest arc distance between two lons.

Parameters:

lon1 - radians

lon2 - radians

Returns:

float distance

DEG_TO_SC

public static final long DEG_TO_SC(double deg)

Convert between decimal degrees and scoords.

Parameters:

deg - degrees

Returns:

long scoords

SC_TO_DEG

public static final double SC_TO_DEG(int sc)

Convert between decimal degrees and scoords.

Parameters:

sc - scoords

Returns:

double decimal degrees

radToDeg

public static final double radToDeg(double rad)

Convert radians to degrees.

Parameters:

rad - radians

Returns:

double decimal degrees

radToDeg

public static final float radToDeg(float rad)

Convert radians to degrees.

Parameters:

rad - radians

Returns:

float decimal degrees

degToRad

public static final double degToRad(double deg)

Convert degrees to radians.

Parameters:

deg - degrees

Returns:

double radians

degToRad

public static final float degToRad(float deg)

Convert degrees to radians.

Parameters:

deg - degrees

Returns:

float radians

hashLatLon

public static final int hashLatLon(float lat,
                                   float lon)

Generate a hashCode value for a lat/lon pair.

Parameters:

lat - latitude

lon - longitude

Returns:

int hashcode

arrayDegToRad

public static final float[] arrayDegToRad(float[] degs)

Converts an array of decimal degrees float lat/lons to float radians in place.

Parameters:

degs - float[] lat/lons in decimal degrees

Returns:

float[] lat/lons in radians

arrayRadToDeg

public static final float[] arrayRadToDeg(float[] rads)

Converts an array of radian float lat/lons to decimal degrees in place.

Parameters:

rads - float[] lat/lons in radians

Returns:

float[] lat/lons in decimal degrees

arrayDegToRad

public static final double[] arrayDegToRad(double[] degs)

Converts an array of decimal degrees double lat/lons to double radians in place.

Parameters:

degs - double[] lat/lons in decimal degrees

Returns:

double[] lat/lons in radians

arrayRadToDeg

public static final double[] arrayRadToDeg(double[] rads)

Converts an array of radian double lat/lons to decimal degrees in place.

Parameters:

rads - double[] lat/lons in radians

Returns:

double[] lat/lons in decimal degrees

normalize_latitude

public static final float normalize_latitude(float lat,
                                             float epsilon)

Deprecated. use normalizeLatitude instead.

normalizeLatitude

public static final float normalizeLatitude(float lat,
                                            float epsilon)

Normalizes radian latitude. Normalizes latitude if at or exceeds epsilon distance from a pole.

Parameters:

lat - float latitude in radians

epsilon - epsilon (>= 0) radians distance from pole

Returns:

float latitude (-PI/2 <= phi <= PI/2)

See Also:

LatLonPoint.normalizeLatitude(double)

normalize_latitude

public static final double normalize_latitude(double lat,
                                              double epsilon)

Deprecated. use normalizeLatitude instead.

normalizeLatitude

public static final double normalizeLatitude(double lat,
                                             double epsilon)

Normalizes radian latitude. Normalizes latitude if at or exceeds epsilon distance from a pole.

Parameters:

lat - double latitude in radians

epsilon - epsilon (>= 0) radians distance from pole

Returns:

double latitude (-PI/2 <= phi <= PI/2)

See Also:

LatLonPoint.normalizeLatitude(double)

wrap_longitude

public static final float wrap_longitude(float lon)

Deprecated. use wrapLongitde instead.

wrapLongitude

public static final float wrapLongitude(float lon)

Sets radian longitude to something sane.

Parameters:

lon - float longitude in radians

Returns:

float longitude (-PI <= lambda < PI)

wrap_longitude

public static final double wrap_longitude(double lon)

Deprecated. use wrapLongitude instead.

wrapLongitude

public static final double wrapLongitude(double lon)

Sets radian longitude to something sane.

Parameters:

lon - double longitude in radians

Returns:

double longitude (-PI <= lambda < PI)

wrapLongitudeDeg

public static final double wrapLongitudeDeg(double lon)

Sets degree longitude to something sane.

Parameters:

lon - double longitude in degrees

Returns:

double longitude (-180 <= lambda < 180)

sphericalUnitsToDeg

public static final float sphericalUnitsToDeg(float u,
                                              float uCircumference)

Converts units (km, nm, miles, etc) to decimal degrees for a spherical planet. This does not check for arc distances > 1/2 planet circumference, which are better represented as (2pi - calculated arc).

Parameters:

u - units float value

uCircumference - units circumference of planet

Returns:

float decimal degrees

sphericalUnitsToRad

public static final float sphericalUnitsToRad(float u,
                                              float uCircumference)

Converts units (km, nm, miles, etc) to arc radians for a spherical planet. This does not check for arc distances > 1/2 planet circumference, which are better represented as (2pi - calculated arc).

Parameters:

u - units float value

uCircumference - units circumference of planet

Returns:

float arc radians

geocentric_latitude

public static final float geocentric_latitude(float lat,
                                              float lon)

Deprecated. use geocentricLatitude instead.

geocentricLatitude

public static final float geocentricLatitude(float lat,
                                             float flat)

Calculate the geocentric latitude given a geographic latitude. According to John Synder:
"The geographic or geodetic latitude is the angle which a line perpendicular to the surface of the ellipsoid at the given point makes with the plane of the equator. ...The geocentric latitude is the angle made by a line to the center of the ellipsoid with the equatorial plane". ( Map Projections --A Working Manual , p 13)

Translated from Ken Anderson's lisp code Freeing the Essence of Computation

Parameters:

lat - float geographic latitude in radians

flat - float flatening factor

Returns:

float geocentric latitude in radians

See Also:

geographic_latitude(float, float)

geographic_latitude

public static final float geographic_latitude(float lat,
                                              float lon)

Deprecated. use geographicLoatitude instead.

geographicLatitude

public static final float geographicLatitude(float lat,
                                             float flat)

Calculate the geographic latitude given a geocentric latitude. Translated from Ken Anderson's lisp code Freeing the Essence of Computation

Parameters:

lat - float geocentric latitude in radians

flat - float flatening factor

Returns:

float geographic latitude in radians

See Also:

geocentric_latitude(float, float)

getScale

public static float getScale(java.awt.geom.Point2D ll1,
                             java.awt.geom.Point2D ll2,
                             Projection projection)

Given a couple of points representing a bounding box, find out what the scale should be in order to make those points appear at the corners of the projection.

Parameters:

ll1 - the upper left coordinates of the bounding box.

ll2 - the lower right coordinates of the bounding box.

projection - the projection to use for other projection parameters, like map width and map height.

getScale

public static float getScale(java.awt.Point point1,
                             java.awt.Point point2,
                             Projection projection)

Given a couple of points representing a bounding box, find out what the scale should be in order to make those points appear at the corners of the projection. This method is generally called from objects dealing with MouseEvents.

Parameters:

point1 - a java.awt.Point reflecting a pixel spot on the projection, usually the upper left corner of the area of interest.

point2 - a java.awt.Point reflecting a pixel spot on the projection, usually the lower right corner of the area of interest.

projection - the projection to use for other projection parameters, like map width and map height.

getScaleFromProjected

public static float getScaleFromProjected(java.awt.geom.Point2D point1,
                                          java.awt.geom.Point2D point2,
                                          Projection projection)

Given a couple of points representing a bounding box of projected coordinates, find out what the scale should be in order to make those points appear at the corners of the projection, with the intention that the bounding box will then fill the projected space.

Parameters:

point1 - a java.awt.Point reflecting a pixel spot on the projection, usually the upper left corner of the area of interest.

point2 - a java.awt.Point reflecting a pixel spot on the projection, usually the lower right corner of the area of interest.

projection - the projection to use for other projection parameters, like map width and map height.

getScale

protected static float getScale(java.awt.geom.Point2D ll1,
                                java.awt.geom.Point2D ll2,
                                java.awt.geom.Point2D point1,
                                java.awt.geom.Point2D point2,
                                Projection projection)

Given a couple of points representing a bounding box, find out what the scale should be in order to make those points appear at the corners of the projection.

Parameters:

ll1 - the upper left coordinates of the bounding box.

ll2 - the lower right coordinates of the bounding box.

point1 - a java.awt.Point reflecting a pixel spot on the projection that matches the ll1 coordinate in the new space, the upper left corner of the area of interest. Where the ll1 is going to go in the new projection.

point2 - a java.awt.Point reflecting a pixel spot on the projection that matches the ll2 coordinate in the new space, usually the lower right corner of the area of interest. Where the ll2 is going to go in the new projection.

projection - the projection to use to query to get the scale for, for projection type and height and width.

isCrossingDateline

public static boolean isCrossingDateline(double leftLon,
                                         double rightLon,
                                         float projScale)

Generic test for seeing if an left longitude value and a right longitude value seem to constitute crossing the dateline.

Parameters:

leftLon - the leftmost longitude, in decimal degrees. Expected to represent the location of the left side of a map window.

rightLon - the rightmost longitude, in decimal degrees. Expected to represent the location of the right side of a map window.

projScale - the projection scale, considered if the two values are very close to each other and leftLon less than rightLon.

Returns:

true if it seems like these two longitude values represent a dateline crossing.

getRatioPoint

public static java.awt.Point getRatioPoint(Projection proj,
                                           java.awt.Point pt1,
                                           java.awt.Point pt2)

Given a projection and the starting point of a box (pt1), look at pt2 to see if it represents the ratio of the projection map size. If it doesn't, provide a point that does. You need to make sure that the proj, pt1 and pt2 is not null.

Parameters:

proj - the projection to use for the calculations.

pt1 - upper left point in pixel space

pt2 - second point in pixel space.

Returns:

new pt that matches projection h/w ratio.

getRatioBox

public static java.awt.geom.Rectangle2D getRatioBox(Projection proj,
                                                    java.awt.geom.Point2D pt1,
                                                    java.awt.geom.Point2D pt2,
                                                    boolean zoomOnCenter)

Given a projection to match against and the starting point of a box (pt1), look at pt2 to see if it represents the ratio of the projection map size. Return a rectangle for the resulting zoom area.

Parameters:

proj - the current projection.

pt1 - first point, where mouse down happened, for instance.

pt2 - latest point, where mouse released happened, for instance.

zoomOnCenter - whether the first point represents the center of the zoom box, or one of the corners.

Returns:

Rectangle2D representing the new zoom box.

getProjectionScreenOutlineCoords

public static double[] getProjectionScreenOutlineCoords(Projection sourceMapProjection)

Walks around the perimeter of the sourceMapProjection and returns the lat/lon coords of the outline.

Parameters:

sourceMapProjection - the source map's projection.

Returns:

double[] in y, x order, in whatever units the source map projection's inverse function returns.

isVisible

public static boolean isVisible(Projection sourceMapProjection,
                                java.awt.geom.Point2D llp)

Returns true if the Point is visible on the provided projection.

Parameters:

sourceMapProjection -

llp -

Returns:

true if the Point is visible on the provided projection.

distance

public static double distance(double[] radianCoords)

Cumulative distance calculated between coords.

Parameters:

radianCoords - lat, lon, lat, lon order

Returns:

distance in radians