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<?php/*------------------------------------------------------------------------------** File: gPoint.php** Description: PHP class to convert Latitude & Longitude coordinates into** UTM & Lambert Conic Conformal Northing/Easting coordinates.** Version: 1.3** Author: Brenor Brophy** Email: brenor dot brophy at gmail dot com** Homepage: brenorbrophy.com**------------------------------------------------------------------------------** COPYRIGHT (c) 2005, 2006, 2007, 2008 BRENOR BROPHY**** The source code included in this package is free software; you can** redistribute it and/or modify it under the terms of the GNU General Public** License as published by the Free Software Foundation. This license can be** read at:**** http://www.opensource.org/licenses/gpl-license.php**** This program 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 General Public License for more details.**------------------------------------------------------------------------------**** Code for datum and UTM conversion was converted from C++ code written by** Chuck Gantz (chuck dot gantz at globalstar dot com) from** http://www.gpsy.com/gpsinfo/geotoutm/ This URL has many other references to** useful information concerning conversion of coordinates.**** Rev History** -----------------------------------------------------------------------------** 1.0 08/25/2005 Initial Release** 1.1 05/15/2006 Added software license language to header comments** Fixed an error in the convertTMtoLL() method. The latitude** calculation had a bunch of variables without $ symbols.** Fixed an error in convertLLtoTM() method, The $this-> was** missing in front of a couple of variables. Thanks to Bob** Robins of Maryland for catching the bugs.** 1.2 05/18/2007 Added default of NULL to $LongOrigin arguement in convertTMtoLL()** and convertLLtoTM() to eliminate warning messages when the** methods are called without a value for $LongOrigin.** 1.3 02/21/2008 Fixed a bug in the distanceFrom method, where the input parameters** were not being converted to radians prior to calculating the** distance. Thanks to Enrico Benco for finding pointing it out.*/define ("meter2nm", (1/1852));define ("nm2meter", 1852);/*------------------------------------------------------------------------------** class gPoint ... for Geographic Point**** This class encapsulates the methods for representing a geographic point on the** earth in three different coordinate systema. Lat/Long, UTM and Lambert Conic** Conformal.*/class gPoint{/* Reference ellipsoids derived from Peter H. Dana's website-** http://www.colorado.edu/geography/gcraft/notes/datum/datum_f.html** email: pdana@pdana.com, web page: www.pdana.com**** Source:** Defense Mapping Agency. 1987b. DMA Technical Report: Supplement to Department** of Defense World Geodetic System 1984 Technical Report. Part I and II.** Washington, DC: Defense Mapping Agency*/var $ellipsoid = array(//Ellipsoid name, Equatorial Radius, square of eccentricity"Airy" =>array (6377563, 0.00667054),"Australian National" =>array (6378160, 0.006694542),"Bessel 1841" =>array (6377397, 0.006674372),"Bessel 1841 Nambia" =>array (6377484, 0.006674372),"Clarke 1866" =>array (6378206, 0.006768658),"Clarke 1880" =>array (6378249, 0.006803511),"Everest" =>array (6377276, 0.006637847),"Fischer 1960 Mercury" =>array (6378166, 0.006693422),"Fischer 1968" =>array (6378150, 0.006693422),"GRS 1967" =>array (6378160, 0.006694605),"GRS 1980" =>array (6378137, 0.00669438),"Helmert 1906" =>array (6378200, 0.006693422),"Hough" =>array (6378270, 0.00672267),"International" =>array (6378388, 0.00672267),"Krassovsky" =>array (6378245, 0.006693422),"Modified Airy" =>array (6377340, 0.00667054),"Modified Everest" =>array (6377304, 0.006637847),"Modified Fischer 1960" =>array (6378155, 0.006693422),"South American 1969" =>array (6378160, 0.006694542),"WGS 60" =>array (6378165, 0.006693422),"WGS 66" =>array (6378145, 0.006694542),"WGS 72" =>array (6378135, 0.006694318),"WGS 84" =>array (6378137, 0.00669438));// Propertiesvar $a; // Equatorial Radiusvar $e2; // Square of eccentricityvar $datum; // Selected datumvar $Xp, $Yp; // X,Y pixel locationvar $lat, $long; // Latitude & Longitude of the pointvar $utmNorthing, $utmEasting, $utmZone; // UTM Coordinates of the pointvar $lccNorthing, $lccEasting; // Lambert coordinates of the pointvar $falseNorthing, $falseEasting; // Origin coordinates for Lambert Projectionvar $latOfOrigin; // For Lambert Projectionvar $longOfOrigin; // For Lambert Projectionvar $firstStdParallel; // For lambert Projectionvar $secondStdParallel; // For lambert Projection// constructorfunction gPoint($datum='WGS 84') // Default datum is WGS 84{$this->a = $this->ellipsoid[$datum][0]; // Set datum Equatorial Radius$this->e2 = $this->ellipsoid[$datum][1]; // Set datum Square of eccentricity$this->datum = $datum; // Save the datum}//// Set/Get X & Y pixel of the point (used if it is being drawn on an image)//function setXY($x, $y){$this->Xp = $x; $this->Yp = $y;}function Xp() { return $this->Xp; }function Yp() { return $this->Yp; }//// Set/Get/Output Longitude & Latitude of the point//function setLongLat($long, $lat){$this->long = $long; $this->lat = $lat;}function Lat() { return $this->lat; }function Long() { return $this->long; }function printLatLong() { printf("Latitude: %1.5f Longitude: %1.5f",$this->lat, $this->long); }//// Set/Get/Output Universal Transverse Mercator Coordinates//function setUTM($easting, $northing, $zone='') // Zone is optional{$this->utmNorthing = $northing;$this->utmEasting = $easting;$this->utmZone = $zone;}function N() { return $this->utmNorthing; }function E() { return $this->utmEasting; }function Z() { return $this->utmZone; }function printUTM() { print( "Northing: ".(int)$this->utmNorthing.", Easting: ".(int)$this->utmEasting.", Zone: ".$this->utmZone); }//// Set/Get/Output Lambert Conic Conformal Coordinates//function setLambert($easting, $northing){$this->lccNorthing = $northing;$this->lccEasting = $easting;}function lccN() { return $this->lccNorthing; }function lccE() { return $this->lccEasting; }function printLambert() { print( "Northing: ".(int)$this->lccNorthing.", Easting: ".(int)$this->lccEasting); }//------------------------------------------------------------------------------//// Convert Longitude/Latitude to UTM//// Equations from USGS Bulletin 1532// East Longitudes are positive, West longitudes are negative.// North latitudes are positive, South latitudes are negative// Lat and Long are in decimal degrees// Written by Chuck Gantz- chuck dot gantz at globalstar dot com, converted to PHP by// Brenor Brophy, brenor dot brophy at gmail dot com//// UTM coordinates are useful when dealing with paper maps. Basically the// map will can cover a single UTM zone which is 6 degrees on longitude.// So you really don't care about an object crossing two zones. You just get a// second map of the other zone. However, if you happen to live in a place that// straddles two zones (For example the Santa Babara area in CA straddles zone 10// and zone 11) Then it can become a real pain having to have two maps all the time.// So relatively small parts of the world (like say California) create their own// version of UTM coordinates that are adjusted to conver the whole area of interest// on a single map. These are called state grids. The projection system is the// usually same as UTM (i.e. Transverse Mercator), but the central meridian// aka Longitude of Origin is selected to suit the logitude of the area being// mapped (like being moved to the central meridian of the area) and the grid// may cover more than the 6 degrees of lingitude found on a UTM map. Areas// that are wide rather than long - think Montana as an example. May still// have to have a couple of maps to cover the whole state because TM projection// looses accuracy as you move further away from the Longitude of Origin, 15 degrees// is usually the limit.//// Now, in the case where we want to generate electronic maps that may be// placed pretty much anywhere on the globe we really don't to deal with the// issue of UTM zones in our coordinate system. We would really just like a// grid that is fully contigious over the area of the map we are drawing. Similiar// to the state grid, but local to the area we are interested in. I call this// Local Transverse Mercator and I have modified the function below to also// make this conversion. If you pass a Longitude value to the function as $LongOrigin// then that is the Longitude of Origin that will be used for the projection.// Easting coordinates will be returned (in meters) relative to that line of// longitude - So an Easting coordinate for a point located East of the longitude// of origin will be a positive value in meters, an Easting coordinate for a point// West of the longitude of Origin will have a negative value in meters. Northings// will always be returned in meters from the equator same as the UTM system. The// UTMZone value will be valid for Long/Lat given - thought it is not meaningful// in the context of Local TM. If a NULL value is passed for $LongOrigin// then the standard UTM coordinates are calculated.//function convertLLtoTM($LongOrigin = NULL){$k0 = 0.9996;$falseEasting = 0.0;//Make sure the longitude is between -180.00 .. 179.9$LongTemp = ($this->long+180)-(integer)(($this->long+180)/360)*360-180; // -180.00 .. 179.9;$LatRad = deg2rad($this->lat);$LongRad = deg2rad($LongTemp);if (!$LongOrigin){ // Do a standard UTM conversion - so findout what zone the point is in$ZoneNumber = (integer)(($LongTemp + 180)/6) + 1;// Special zone for South Norwayif( $this->lat >= 56.0 && $this->lat < 64.0 && $LongTemp >= 3.0 && $LongTemp < 12.0 ) // Fixed 1.1$ZoneNumber = 32;// Special zones for Svalbardif( $this->lat >= 72.0 && $this->lat < 84.0 ){if( $LongTemp >= 0.0 && $LongTemp < 9.0 ) $ZoneNumber = 31;else if( $LongTemp >= 9.0 && $LongTemp < 21.0 ) $ZoneNumber = 33;else if( $LongTemp >= 21.0 && $LongTemp < 33.0 ) $ZoneNumber = 35;else if( $LongTemp >= 33.0 && $LongTemp < 42.0 ) $ZoneNumber = 37;}$LongOrigin = ($ZoneNumber - 1)*6 - 180 + 3; //+3 puts origin in middle of zone//compute the UTM Zone from the latitude and longitude$this->utmZone = sprintf("%d%s", $ZoneNumber, $this->UTMLetterDesignator());// We also need to set the false Easting value adjust the UTM easting coordinate$falseEasting = 500000.0;}$LongOriginRad = deg2rad($LongOrigin);$eccPrimeSquared = ($this->e2)/(1-$this->e2);$N = $this->a/sqrt(1-$this->e2*sin($LatRad)*sin($LatRad));$T = tan($LatRad)*tan($LatRad);$C = $eccPrimeSquared*cos($LatRad)*cos($LatRad);$A = cos($LatRad)*($LongRad-$LongOriginRad);$M = $this->a*((1 - $this->e2/4 - 3*$this->e2*$this->e2/64 - 5*$this->e2*$this->e2*$this->e2/256)*$LatRad- (3*$this->e2/8 + 3*$this->e2*$this->e2/32 + 45*$this->e2*$this->e2*$this->e2/1024)*sin(2*$LatRad)+ (15*$this->e2*$this->e2/256 + 45*$this->e2*$this->e2*$this->e2/1024)*sin(4*$LatRad)- (35*$this->e2*$this->e2*$this->e2/3072)*sin(6*$LatRad));$this->utmEasting = ($k0*$N*($A+(1-$T+$C)*$A*$A*$A/6+ (5-18*$T+$T*$T+72*$C-58*$eccPrimeSquared)*$A*$A*$A*$A*$A/120)+ $falseEasting);$this->utmNorthing = ($k0*($M+$N*tan($LatRad)*($A*$A/2+(5-$T+9*$C+4*$C*$C)*$A*$A*$A*$A/24+ (61-58*$T+$T*$T+600*$C-330*$eccPrimeSquared)*$A*$A*$A*$A*$A*$A/720)));if($this->lat < 0)$this->utmNorthing += 10000000.0; //10000000 meter offset for southern hemisphere}//// This routine determines the correct UTM letter designator for the given latitude// returns 'Z' if latitude is outside the UTM limits of 84N to 80S// Written by Chuck Gantz- chuck dot gantz at globalstar dot com, converted to PHP by// Brenor Brophy, brenor dot brophy at gmail dot com//function UTMLetterDesignator(){if((84 >= $this->lat) && ($this->lat >= 72)) $LetterDesignator = 'X';else if((72 > $this->lat) && ($this->lat >= 64)) $LetterDesignator = 'W';else if((64 > $this->lat) && ($this->lat >= 56)) $LetterDesignator = 'V';else if((56 > $this->lat) && ($this->lat >= 48)) $LetterDesignator = 'U';else if((48 > $this->lat) && ($this->lat >= 40)) $LetterDesignator = 'T';else if((40 > $this->lat) && ($this->lat >= 32)) $LetterDesignator = 'S';else if((32 > $this->lat) && ($this->lat >= 24)) $LetterDesignator = 'R';else if((24 > $this->lat) && ($this->lat >= 16)) $LetterDesignator = 'Q';else if((16 > $this->lat) && ($this->lat >= 8)) $LetterDesignator = 'P';else if(( 8 > $this->lat) && ($this->lat >= 0)) $LetterDesignator = 'N';else if(( 0 > $this->lat) && ($this->lat >= -8)) $LetterDesignator = 'M';else if((-8 > $this->lat) && ($this->lat >= -16)) $LetterDesignator = 'L';else if((-16 > $this->lat) && ($this->lat >= -24)) $LetterDesignator = 'K';else if((-24 > $this->lat) && ($this->lat >= -32)) $LetterDesignator = 'J';else if((-32 > $this->lat) && ($this->lat >= -40)) $LetterDesignator = 'H';else if((-40 > $this->lat) && ($this->lat >= -48)) $LetterDesignator = 'G';else if((-48 > $this->lat) && ($this->lat >= -56)) $LetterDesignator = 'F';else if((-56 > $this->lat) && ($this->lat >= -64)) $LetterDesignator = 'E';else if((-64 > $this->lat) && ($this->lat >= -72)) $LetterDesignator = 'D';else if((-72 > $this->lat) && ($this->lat >= -80)) $LetterDesignator = 'C';else $LetterDesignator = 'Z'; //This is here as an error flag to show that the Latitude is outside the UTM limitsreturn($LetterDesignator);}//------------------------------------------------------------------------------//// Convert UTM to Longitude/Latitude//// Equations from USGS Bulletin 1532// East Longitudes are positive, West longitudes are negative.// North latitudes are positive, South latitudes are negative// Lat and Long are in decimal degrees.// Written by Chuck Gantz- chuck dot gantz at globalstar dot com, converted to PHP by// Brenor Brophy, brenor dot brophy at gmail dot com//// If a value is passed for $LongOrigin then the function assumes that// a Local (to the Longitude of Origin passed in) Transverse Mercator// coordinates is to be converted - not a UTM coordinate. This is the// complementary function to the previous one. The function cannot// tell if a set of Northing/Easting coordinates are in the North// or South hemesphere - they just give distance from the equator not// direction - so only northern hemesphere lat/long coordinates are returned.// If you live south of the equator there is a note later in the code// explaining how to have it just return southern hemesphere lat/longs.//function convertTMtoLL($LongOrigin = NULL){$k0 = 0.9996;$e1 = (1-sqrt(1-$this->e2))/(1+sqrt(1-$this->e2));$falseEasting = 0.0;$y = $this->utmNorthing;if (!$LongOrigin){ // It is a UTM coordinate we want to convertsscanf($this->utmZone,"%d%s",$ZoneNumber,$ZoneLetter);if($ZoneLetter >= 'N')$NorthernHemisphere = 1;//point is in northern hemisphereelse{$NorthernHemisphere = 0;//point is in southern hemisphere$y -= 10000000.0;//remove 10,000,000 meter offset used for southern hemisphere}$LongOrigin = ($ZoneNumber - 1)*6 - 180 + 3; //+3 puts origin in middle of zone$falseEasting = 500000.0;}// $y -= 10000000.0; // Uncomment line to make LOCAL coordinates return southern hemesphere Lat/Long$x = $this->utmEasting - $falseEasting; //remove 500,000 meter offset for longitude$eccPrimeSquared = ($this->e2)/(1-$this->e2);$M = $y / $k0;$mu = $M/($this->a*(1-$this->e2/4-3*$this->e2*$this->e2/64-5*$this->e2*$this->e2*$this->e2/256));$phi1Rad = $mu + (3*$e1/2-27*$e1*$e1*$e1/32)*sin(2*$mu)+ (21*$e1*$e1/16-55*$e1*$e1*$e1*$e1/32)*sin(4*$mu)+(151*$e1*$e1*$e1/96)*sin(6*$mu);$phi1 = rad2deg($phi1Rad);$N1 = $this->a/sqrt(1-$this->e2*sin($phi1Rad)*sin($phi1Rad));$T1 = tan($phi1Rad)*tan($phi1Rad);$C1 = $eccPrimeSquared*cos($phi1Rad)*cos($phi1Rad);$R1 = $this->a*(1-$this->e2)/pow(1-$this->e2*sin($phi1Rad)*sin($phi1Rad), 1.5);$D = $x/($N1*$k0);$tlat = $phi1Rad - ($N1*tan($phi1Rad)/$R1)*($D*$D/2-(5+3*$T1+10*$C1-4*$C1*$C1-9*$eccPrimeSquared)*$D*$D*$D*$D/24+(61+90*$T1+298*$C1+45*$T1*$T1-252*$eccPrimeSquared-3*$C1*$C1)*$D*$D*$D*$D*$D*$D/720); // fixed in 1.1$this->lat = rad2deg($tlat);$tlong = ($D-(1+2*$T1+$C1)*$D*$D*$D/6+(5-2*$C1+28*$T1-3*$C1*$C1+8*$eccPrimeSquared+24*$T1*$T1)*$D*$D*$D*$D*$D/120)/cos($phi1Rad);$this->long = $LongOrigin + rad2deg($tlong);}//------------------------------------------------------------------------------// Configure a Lambert Conic Conformal Projection//// falseEasting & falseNorthing are just an offset in meters added to the final// coordinate calculated.//// longOfOrigin & LatOfOrigin are the "center" latitiude and longitude of the// area being projected. All coordinates will be calculated in meters relative// to this point on the earth.//// firstStdParallel & secondStdParallel are the two lines of longitude (that// is they run east-west) that define where the "cone" intersects the earth.// Simply put they should bracket the area being projected.//// google is your friend to find out more//function configLambertProjection ($falseEasting, $falseNorthing,$longOfOrigin, $latOfOrigin,$firstStdParallel, $secondStdParallel){$this->falseEasting = $falseEasting;$this->falseNorthing = $falseNorthing;$this->longOfOrigin = $longOfOrigin;$this->latOfOrigin = $latOfOrigin;$this->firstStdParallel = $firstStdParallel;$this->secondStdParallel = $secondStdParallel;}//------------------------------------------------------------------------------//// Convert Longitude/Latitude to Lambert Conic Easting/Northing//// This routine will convert a Latitude/Longitude coordinate to an Northing/// Easting coordinate on a Lambert Conic Projection. The configLambertProjection()// function should have been called prior to this one to setup the specific// parameters for the projection. The Northing/Easting parameters calculated are// in meters (because the datum used is in meters) and are relative to the// falseNorthing/falseEasting coordinate. Which in turn is relative to the// Lat/Long of origin The formula were obtained from URL:// http://www.ihsenergy.com/epsg/guid7_2.html.// Code was written by Brenor Brophy, brenor dot brophy at gmail dot com//function convertLLtoLCC(){$e = sqrt($this->e2);$phi = deg2rad($this->lat); // Latitude to convert$phi1 = deg2rad($this->firstStdParallel); // Latitude of 1st std parallel$phi2 = deg2rad($this->secondStdParallel); // Latitude of 2nd std parallel$lamda = deg2rad($this->long); // Lonitude to convert$phio = deg2rad($this->latOfOrigin); // Latitude of Origin$lamdao = deg2rad($this->longOfOrigin); // Longitude of Origin$m1 = cos($phi1) / sqrt(( 1 - $this->e2*sin($phi1)*sin($phi1)));$m2 = cos($phi2) / sqrt(( 1 - $this->e2*sin($phi2)*sin($phi2)));$t1 = tan((pi()/4)-($phi1/2)) / pow(( ( 1 - $e*sin($phi1) ) / ( 1 + $e*sin($phi1) )),$e/2);$t2 = tan((pi()/4)-($phi2/2)) / pow(( ( 1 - $e*sin($phi2) ) / ( 1 + $e*sin($phi2) )),$e/2);$to = tan((pi()/4)-($phio/2)) / pow(( ( 1 - $e*sin($phio) ) / ( 1 + $e*sin($phio) )),$e/2);$t = tan((pi()/4)-($phi /2)) / pow(( ( 1 - $e*sin($phi ) ) / ( 1 + $e*sin($phi ) )),$e/2);$n = (log($m1)-log($m2)) / (log($t1)-log($t2));$F = $m1/($n*pow($t1,$n));$rf = $this->a*$F*pow($to,$n);$r = $this->a*$F*pow($t,$n);$theta = $n*($lamda - $lamdao);$this->lccEasting = $this->falseEasting + $r*sin($theta);$this->lccNorthing = $this->falseNorthing + $rf - $r*cos($theta);}//------------------------------------------------------------------------------//// Convert Easting/Northing on a Lambert Conic projection to Longitude/Latitude//// This routine will convert a Lambert Northing/Easting coordinate to an// Latitude/Longitude coordinate. The configLambertProjection() function should// have been called prior to this one to setup the specific parameters for the// projection. The Northing/Easting parameters are in meters (because the datum// used is in meters) and are relative to the falseNorthing/falseEasting// coordinate. Which in turn is relative to the Lat/Long of origin The formula// were obtained from URL http://www.ihsenergy.com/epsg/guid7_2.html. Code// was written by Brenor Brophy, brenor dot brophy at gmail dot com//function convertLCCtoLL(){$e = sqrt($this->e2);$phi1 = deg2rad($this->firstStdParallel); // Latitude of 1st std parallel$phi2 = deg2rad($this->secondStdParallel); // Latitude of 2nd std parallel$phio = deg2rad($this->latOfOrigin); // Latitude of Origin$lamdao = deg2rad($this->longOfOrigin); // Longitude of Origin$E = $this->lccEasting;$N = $this->lccNorthing;$Ef = $this->falseEasting;$Nf = $this->falseNorthing;$m1 = cos($phi1) / sqrt(( 1 - $this->e2*sin($phi1)*sin($phi1)));$m2 = cos($phi2) / sqrt(( 1 - $this->e2*sin($phi2)*sin($phi2)));$t1 = tan((pi()/4)-($phi1/2)) / pow(( ( 1 - $e*sin($phi1) ) / ( 1 + $e*sin($phi1) )),$e/2);$t2 = tan((pi()/4)-($phi2/2)) / pow(( ( 1 - $e*sin($phi2) ) / ( 1 + $e*sin($phi2) )),$e/2);$to = tan((pi()/4)-($phio/2)) / pow(( ( 1 - $e*sin($phio) ) / ( 1 + $e*sin($phio) )),$e/2);$n = (log($m1)-log($m2)) / (log($t1)-log($t2));$F = $m1/($n*pow($t1,$n));$rf = $this->a*$F*pow($to,$n);$r_ = sqrt( pow(($E-$Ef),2) + pow(($rf-($N-$Nf)),2) );$t_ = pow($r_/($this->a*$F),(1/$n));$theta_ = atan(($E-$Ef)/($rf-($N-$Nf)));$lamda = $theta_/$n + $lamdao;$phi0 = (pi()/2) - 2*atan($t_);$phi1 = (pi()/2) - 2*atan($t_*pow(((1-$e*sin($phi0))/(1+$e*sin($phi0))),$e/2));$phi2 = (pi()/2) - 2*atan($t_*pow(((1-$e*sin($phi1))/(1+$e*sin($phi1))),$e/2));$phi = (pi()/2) - 2*atan($t_*pow(((1-$e*sin($phi2))/(1+$e*sin($phi2))),$e/2));$this->lat = rad2deg($phi);$this->long = rad2deg($lamda);}//------------------------------------------------------------------------------// This is a useful function that returns the Great Circle distance from the// gPoint to another Long/Lat coordinate//// Result is returned as meters//function distanceFrom($lon1, $lat1){$lon1 = deg2rad($lon1); $lat1 = deg2rad($lat1); // Added in 1.3$lon2 = deg2rad($this->Long()); $lat2 = deg2rad($this->Lat());$theta = $lon2 - $lon1;$dist = acos(sin($lat1) * sin($lat2) + cos($lat1) * cos($lat2) * cos($theta));// Alternative formula supposed to be more accurate for short distances// $dist = 2*asin(sqrt( pow(sin(($lat1-$lat2)/2),2) + cos($lat1)*cos($lat2)*pow(sin(($lon1-$lon2)/2),2)));return ( $dist * 6366710 ); // from http://williams.best.vwh.net/avform.htm#GCF}//------------------------------------------------------------------------------// This function also calculates the distance between two points. In this case// it just uses Pythagoras's theorm using TM coordinates.//function distanceFromTM(&$pt){$E1 = $pt->E(); $N1 = $pt->N();$E2 = $this->E(); $N2 = $this->N();$dist = sqrt(pow(($E1-$E2),2)+pow(($N1-$N2),2));return $dist;}//------------------------------------------------------------------------------// This function geo-references a geoPoint to a given map. This means that it// calculates the x,y pixel coordinate that coresponds to the Lat/Long value of// the geoPoint. The calculation is done using the Transverse Mercator(TM)// coordinates of the gPoint with respect to the TM coordinates of the center// point of the map. So this only makes sense if you are using Local TM// projection.//// $rX & $rY are the pixel coordinates that corespond to the Northing/Easting// ($rE/$rN) coordinate it is to this coordinate that the point will be// geo-referenced. The $LongOrigin is needed to make sure the Easting/Northing// coordinates of the point are correctly converted.//function gRef($rX, $rY, $rE, $rN, $Scale, $LongOrigin){$this->convertLLtoTM($LongOrigin);$x = (($this->E() - $rE) / $Scale) // The easting in meters times the scale to get pixels// is relative to the center of the image so adjust to+ ($rX); // the left coordinate.$y = $rY - // Adjust to bottom coordinate.(($rN - $this->N()) / $Scale); // The northing in meters// relative to the equator. Subtract center point northing// to get relative to image center and convert meters to pixels$this->setXY((int)$x,(int)$y); // Save the geo-referenced result.}} // end of class gPoint?>