Switched from hardcoded values to CSV files for datum definitions.

Non-WGS84 maps now fit correctly when defined using map grid.

gpxsee.pro

@@ -92,7 +92,8 @@ HEADERS += src/config.h \
     src/utm.h \
     src/lambertconic.h \
     src/ellipsoid.h \
-    src/ozf.h
+    src/ozf.h \
+    src/datum.h
 SOURCES += src/main.cpp \
     src/gui.cpp \
     src/poi.cpp \
@@ -158,7 +159,8 @@ SOURCES += src/main.cpp \
     src/utm.cpp \
     src/lambertconic.cpp \
     src/ellipsoid.cpp \
-    src/ozf.cpp
+    src/ozf.cpp \
+    src/datum.cpp
 RESOURCES += gpxsee.qrc
 TRANSLATIONS = lang/gpxsee_cs.ts \
     lang/gpxsee_sv.ts

pkg/datums.csv

@@ -0,0 +1,123 @@
+Adindan,4201,5,-162,-12,206
+Afgooye,4205,15,-43,-163,45
+Ain el Abd 1970,4204,14,-150,-251,-2
+Anna 1 Astro 1965,4708,2,-491,-22,435
+Arc 1950,4209,5,-143,-90,-294
+Arc 1960,4210,5,-160,-8,-300
+Ascension Island 1958,4712,14,-207,107,52
+Astro B4 Sorol Atoll,4707,14,114,-116,-333
+Astro Beacon 1945,4709,14,145,75,-272
+Astro DOS 71/4,4710,14,-320,550,-494
+Astronomic Stn 1952,4711,14,124,-234,-25
+Australian Geodetic 1966,4202,2,-133,-48,148
+Australian Geodetic 1984,4203,2,-134,-48,149
+Australian Geocentric 1994 (GDA94),4283,11,0,0,0 
+Austrian,4312,3,594,84,471
+Bellevue (IGN),4714,14,-127,-769,472
+Bermuda 1957,4216,4,-73,213,296
+Bogota Observatory,4218,14,307,304,-318
+Campo Inchauspe,4221,14,-148,136,90
+Canton Astro 1966,4716,14,298,-304,-375
+Cape,4222,5,-136,-108,-292
+Cape Canaveral,4717,4,-2,150,181
+Carthage,4223,5,-263,6,431
+CH-1903,4149,3,674,15,405
+Chatham 1971,4672,14,175,-38,113
+Chua Astro,4224,14,-134,229,-29
+Corrego Alegre,4225,14,-206,172,-6
+Djakarta (Batavia),4211,3,-377,681,-50
+DOS 1968,,14,230,-199,-752
+Easter Island 1967,4719,14,211,147,111
+Egypt,,14,-130,-117,-151
+European 1950,4230,14,-87,-98,-121
+European 1950 (Mean France),,14,-87,-96,-120
+European 1950 (Spain and Portugal),,14,-84,-107,-120 
+European 1979,4668,14,-86,-98,-119
+Finland Hayford,4123,14,-78,-231,-97
+Gandajika Base,4233,14,-133,-321,50
+Geodetic Datum 1949,4272,14,84,-22,209
+GGRS 87,4121,11,-199.87,74.79,246.62
+Guam 1963,4675,4,-100,-248,259
+GUX 1 Astro,4718,14,252,-209,-751
+Hartebeeshoek94,4148,20,0,0,0
+Hermannskogel,3906,3,653,-212,449
+Hjorsey 1955,4658,14,-73,46,-86
+Hong Kong 1963,4739,14,-156,-271,-189
+Hu-Tzu-Shan,4236,14,-634,-549,-201
+Indian Bangladesh,4682,6,289,734,257
+Indian Thailand,4240,6,214,836,303
+Israeli,4281,23,-235,-85,264
+Ireland 1965,4299,1,506,-122,611
+ISTS 073 Astro 1969,4724,14,208,-435,-229
+Johnston Island,4725,14,191,-77,-204
+Kandawala,4244,6,-97,787,86
+Kerguelen Island,4698,14,145,-187,103
+Kertau 1948,4245,7,-11,851,5
+L.C. 5 Astro,4726,4,42,124,147
+Liberia 1964,4251,5,-90,40,88
+Luzon Mindanao,,4,-133,-79,-72
+Luzon Philippines,4253,4,-133,-77,-51
+Mahe 1971,4256,5,41,-220,-134
+Marco Astro,4616,14,-289,-124,60
+Massawa,4262,3,639,405,60
+Merchich,4261,5,31,146,47
+Midway Astro 1961,4727,14,912,-58,1227
+Minna,4263,5,-92,-93,122
+NAD27 Alaska,,4,-5,135,172
+NAD27 Bahamas,,4,-4,154,178
+NAD27 Canada,,4,-10,158,187
+NAD27 Canal Zone,,4,0,125,201
+NAD27 Caribbean,,4,-7,152,178
+NAD27 Central,,4,0,125,194
+NAD27 CONUS,,4,-8,160,176
+NAD27 Cuba,,4,-9,152,178
+NAD27 Greenland,,4,11,114,195
+NAD27 Mexico,,4,-12,130,190
+NAD27 San Salvador,,4,1,140,165
+NAD83,4269,11,0,0,0
+Nahrwn Masirah Ilnd,,5,-247,-148,369
+Nahrwn Saudi Arbia,,5,-231,-196,482
+Nahrwn United Arab,,5,-249,-156,381
+Naparima BWI,4271,14,-2,374,172
+NGO1948,4273,27,315,-217,528
+NTF France,4275,24,-168,-60,320
+Norsk,4817,27,278,93,474
+NZGD1949,4272,14,84,-22,209
+NZGD2000,4167,20,0,0,0
+Observatorio 1966,4182,14,-425,-169,81
+Old Egyptian,4229,12,-130,110,-13
+Old Hawaiian,4135,4,61,-285,-181
+Oman,4232,5,-346,-1,224
+Ord Srvy Grt Britn,4277,0,375,-111,431
+Pico De Las Nieves,4728,14,-307,-92,127
+Pitcairn Astro 1967,4729,14,185,165,42
+Potsdam Rauenberg DHDN,4314,3,606,23,413
+Prov So Amrican 1956,4248,14,-288,175,-376
+Prov So Chilean 1963,4254,14,16,196,93
+Puerto Rico,4139,4,11,72,-101
+Pulkovo 1942 (1),4284,15,28,-130,-95
+Pulkovo 1942 (2),4284,15,28,-130,-95
+Qatar National,4285,14,-128,-283,22
+Qornoq,4287,14,164,138,-189
+Reunion,4626,14,94,-948,-1262
+Rijksdriehoeksmeting,4289,3,593,26,478
+Rome 1940,4806,14,-225,-65,9
+RT 90,4124,3,498,-36,568
+S42,4179,15,28,-121,-77
+Santo (DOS),4730,14,170,42,84
+Sao Braz,4184,14,-203,141,53
+Sapper Hill 1943,4292,14,-355,16,74
+Schwarzeck,4293,21,616,97,-251
+South American 1969,4291,16,-57,1,-41
+South Asia,,8,7,-10,-26
+Southeast Base,4615,14,-499,-249,314
+Southwest Base,4183,14,-104,167,-38
+Timbalai 1948,4298,6,-689,691,-46
+Tokyo,4301,3,-128,481,664
+Tristan Astro 1968,4734,14,-632,438,-609
+Viti Levu 1916,4731,5,51,391,-36
+Wake-Eniwetok 1960,4732,13,101,52,-39
+WGS 72,4322,19,0,0,5
+WGS 84,4326,20,0,0,0
+Yacare,4309,14,-155,171,37
+Zanderij,4311,14,-265,120,-358

pkg/ellipsoids.csv

@@ -0,0 +1,30 @@
+0,Airy 1830,6377563.396,299.3249646
+1,Modified Airy,6377340.189,299.3249646
+2,Australian National,6378160.0,298.25 
+3,Bessel 1841,6377397.155,299.1528128
+4,Clarke 1866,6378206.4,294.9786982
+5,Clarke 1880,6378249.145,293.465
+6,Everest (India 1830),6377276.345,300.8017
+7,Everest (1948),6377304.063,300.8017
+8,Modified Fischer 1960,6378155.0,298.3
+9,Everest (Pakistan),6377309.613,300.8017
+10,Indonesian 1974,6378160.0,298.247
+11,GRS 80,6378137.0,298.257222101
+12,Helmert 1906,6378200.0,298.3
+13,Hough 1960,6378270.0,297.0
+14,International 1924,6378388.0,297.0
+15,Krassovsky 1940,6378245.0,298.3
+16,South American 1969,6378160.0,298.25
+17,Everest (Malaysia 1969),6377295.664,300.8017
+18,Everest (Sabah Sarawak),6377298.556,300.8017
+19,WGS 72,6378135.0,298.26
+20,WGS 84,6378137.0,298.257223563
+21,Bessel 1841 (Namibia),6377483.865,299.1528128
+22,Everest (India 1956),6377301.243,300.8017
+23,Clarke 1880 Palestine,6378300.789,293.466 
+24,Clarke 1880 IGN,6378249.2,293.466021
+25,Hayford 1909,6378388.0,296.959263
+26,Clarke 1858,6378350.87,294.26
+27,Bessel 1841 (Norway),6377492.0176,299.1528
+28,Plessis 1817 (France),6376523.0,308.6409971
+29,Hayford 1924,6378388.0,297.0

src/config.h

@@ -13,6 +13,8 @@
 #define FONT_SIZE       12
 #define SCREEN_DPI      96.0
 
+#define ELLIPSOID_FILE  QString("ellipsoids.csv")
+#define DATUM_FILE      QString("datums.csv")
 #define MAP_FILE        QString("maps.txt")
 #define MAP_DIR         QString("maps")
 #define POI_DIR         QString("POI")
@@ -29,12 +31,16 @@
 #define GLOBAL_DIR      QString("/usr/share/gpxsee")
 #endif
 
-#define USER_MAP_DIR    USER_DIR + QString("/") + MAP_DIR
+#define USER_ELLIPSOID_FILE    USER_DIR + QString("/") + ELLIPSOID_FILE
-#define USER_MAP_FILE   USER_DIR + QString("/") + MAP_FILE
+#define USER_DATUM_FILE        USER_DIR + QString("/") + DATUM_FILE
-#define USER_POI_DIR    USER_DIR + QString("/") + POI_DIR
+#define USER_MAP_DIR           USER_DIR + QString("/") + MAP_DIR
-#define GLOBAL_MAP_DIR  GLOBAL_DIR + QString("/") + MAP_DIR
+#define USER_MAP_FILE          USER_DIR + QString("/") + MAP_FILE
-#define GLOBAL_MAP_FILE GLOBAL_DIR + QString("/") + MAP_FILE
+#define USER_POI_DIR           USER_DIR + QString("/") + POI_DIR
-#define GLOBAL_POI_DIR  GLOBAL_DIR + QString("/") + POI_DIR
+#define GLOBAL_ELLIPSOID_FILE  GLOBAL_DIR + QString("/") + ELLIPSOID_FILE
-#define TILES_DIR       USER_DIR + QString("/tiles")
+#define GLOBAL_DATUM_FILE      GLOBAL_DIR + QString("/") + DATUM_FILE
+#define GLOBAL_MAP_DIR         GLOBAL_DIR + QString("/") + MAP_DIR
+#define GLOBAL_MAP_FILE        GLOBAL_DIR + QString("/") + MAP_FILE
+#define GLOBAL_POI_DIR         GLOBAL_DIR + QString("/") + POI_DIR
+#define TILES_DIR              USER_DIR + QString("/tiles")
 
 #endif /* CONFIG_H */

src/datum.cpp

@@ -0,0 +1,83 @@
+#include <QFile>
+#include "wgs84.h"
+#include "datum.h"
+
+
+static QMap<QString, Datum> WGS84()
+{
+	QMap<QString, Datum> map;
+	map.insert("WGS 84", Datum(Ellipsoid(WGS84_RADIUS, WGS84_FLATTENING),
+	  0, 0, 0));
+	return map;
+}
+
+QMap<QString, Datum> Datum::_datums = WGS84();
+QString Datum::_errorString;
+int Datum::_errorLine = 0;
+
+Datum Datum::datum(const QString &name)
+{
+	QMap<QString, Datum>::const_iterator it = _datums.find(name);
+
+	if (it == _datums.end())
+		return Datum();
+
+	return it.value();
+}
+
+bool Datum::loadList(const QString &path)
+{
+	QFile file(path);
+	bool res;
+
+	if (!file.open(QFile::ReadOnly)) {
+		_errorString = qPrintable(file.errorString());
+		return false;
+	}
+
+	_errorLine = 1;
+	_errorString.clear();
+
+	while (!file.atEnd()) {
+		QByteArray line = file.readLine();
+		QList<QByteArray> list = line.split(',');
+		if (list.size() != 6) {
+			_errorString = "Format error";
+			return false;
+		}
+
+		int eid = list[2].trimmed().toInt(&res);
+		if (!res) {
+			_errorString = "Invalid ellipsoid id";
+			return false;
+		}
+		double dx = list[3].trimmed().toDouble(&res);
+		if (!res) {
+			_errorString = "Invalid dx";
+			return false;
+		}
+		double dy = list[4].trimmed().toDouble(&res);
+		if (!res) {
+			_errorString = "Invalid dy";
+			return false;
+		}
+		double dz = list[5].trimmed().toDouble(&res);
+		if (!res) {
+			_errorString = "Invalid dz";
+			return false;
+		}
+
+		Ellipsoid e = Ellipsoid::ellipsoid(eid);
+		if (e.isNull()) {
+			_errorString = "Unknown ellipsoid ID";
+			return false;
+		}
+
+		Datum d(e, dx, dy, dz);
+		_datums.insert(list[0].trimmed(), d);
+
+		_errorLine++;
+	}
+
+	return true;
+}

src/datum.h

@@ -0,0 +1,38 @@
+#ifndef DATUM_H
+#define DATUM_H
+
+#include <QMap>
+#include "ellipsoid.h"
+
+class Datum
+{
+public:
+	Datum() : _ellipsoid(Ellipsoid()), _dx(0), _dy(0), _dz(0) {}
+	Datum(const Ellipsoid &ellipsoid, double dx, double dy, double dz)
+	  : _ellipsoid(ellipsoid), _dx(dx), _dy(dy), _dz(dz) {}
+
+	const Ellipsoid &ellipsoid() const {return _ellipsoid;}
+	double dx() const {return _dx;}
+	double dy() const {return _dy;}
+	double dz() const {return _dz;}
+
+	bool isNull() const {return _ellipsoid.isNull();}
+	bool isWGS84() const
+	  {return _ellipsoid.isWGS84() && _dx == 0 && _dy == 0 && _dz == 0;}
+
+	static bool loadList(const QString &path);
+	static const QString &errorString() {return _errorString;}
+	static int errorLine() {return _errorLine;}
+
+	static Datum datum(const QString &name);
+
+private:
+	Ellipsoid _ellipsoid;
+	double _dx, _dy, _dz;
+
+	static QMap<QString, Datum> _datums;
+	static QString _errorString;
+	static int _errorLine;
+};
+
+#endif // DATUM_H

src/ellipsoid.cpp

@@ -1,42 +1,62 @@
-#include <cmath>
+#include <QFile>
-#include <QString>
-#include "wgs84.h"
 #include "ellipsoid.h"
 
+QMap<int, Ellipsoid> Ellipsoid::_ellipsoids;
+QString Ellipsoid::_errorString;
+int Ellipsoid::_errorLine = 0;
 
-#define INTERNATIONAL_RADIUS     6378388.0
+Ellipsoid Ellipsoid::ellipsoid(int id)
-#define INTERNATIONAL_FLATTENING (1.0/297.0)
-#define KRASSOVSKY_RADIUS        6378245.0
-#define KRASSOVSKY_FLATTENING    (1.0/298.3)
-#define CLARKE1866_RADIUS        6378206.4
-#define CLARKE1866_FLATTENING    (1.0/294.9786982)
-#define GRS80_RADIUS             6378137.0
-#define GRS80_FLATTENING         (1.0/298.257222101)
-#define WGS72_RADIUS             6378135.0
-#define WGS72_FLATTENING         (1.0/298.26)
-#define GRS67_RADIUS             6378160.0
-#define GRS67_FLATTENING         (1.0/298.25)
-
-
-// Must be in Ellipsoid::Name order!
-struct {double radius; double flattening;} static ellipsoids[] = {
-	{CLARKE1866_RADIUS, CLARKE1866_FLATTENING},
-	{GRS80_RADIUS, GRS80_FLATTENING},
-	{INTERNATIONAL_RADIUS, INTERNATIONAL_FLATTENING},
-	{KRASSOVSKY_RADIUS, KRASSOVSKY_FLATTENING},
-	{WGS84_RADIUS, WGS84_FLATTENING},
-	{WGS72_RADIUS, WGS72_FLATTENING},
-	{GRS67_RADIUS, GRS67_FLATTENING}
-};
-
-Ellipsoid::Ellipsoid()
 {
-	_radius = WGS84_RADIUS;
+	QMap<int, Ellipsoid>::const_iterator it = _ellipsoids.find(id);
-	_flattening = WGS84_FLATTENING;
+
+	if (it == _ellipsoids.end())
+		return Ellipsoid();
+
+	return it.value();
 }
 
-Ellipsoid::Ellipsoid(Name name)
+bool Ellipsoid::loadList(const QString &path)
 {
-	_radius = ellipsoids[name].radius;
+	QFile file(path);
-	_flattening = ellipsoids[name].flattening;
+	bool res;
+
+	if (!file.open(QFile::ReadOnly)) {
+		_errorString = qPrintable(file.errorString());
+		return false;
+	}
+
+	_errorLine = 1;
+	_errorString.clear();
+
+	while (!file.atEnd()) {
+		QByteArray line = file.readLine();
+		QList<QByteArray> list = line.split(',');
+		if (list.size() != 4) {
+			_errorString = "Format error";
+			return false;
+		}
+
+		int id = list[0].trimmed().toInt(&res);
+		if (!res) {
+			_errorString = "Invalid ellipsoid id";
+			return false;
+		}
+		double radius = list[2].trimmed().toDouble(&res);
+		if (!res) {
+			_errorString = "Invalid ellipsoid radius";
+			return false;
+		}
+		double flattening = list[3].trimmed().toDouble(&res);
+		if (!res) {
+			_errorString = "Invalid ellipsoid flattening";
+			return false;
+		}
+
+		Ellipsoid e(radius, 1.0/flattening);
+		_ellipsoids.insert(id, e);
+
+		_errorLine++;
+	}
+
+	return true;
 }

src/ellipsoid.h

@@ -1,28 +1,37 @@
 #ifndef ELLIPSOID_H
 #define ELLIPSOID_H
 
+#include <QString>
+#include <QMap>
+#include "wgs84.h"
+
 class Ellipsoid
 {
 public:
-	enum Name {
+	Ellipsoid() : _radius(-1.0), _flattening(-1.0) {}
-		Clarke1866,
+	Ellipsoid(double radius, double flattening)
-		GRS80,
+	  : _radius(radius), _flattening(flattening) {}
-		International1924,
-		Krassowsky1940,
-		WGS84,
-		WGS72,
-		GRS67
-	};
-
-	Ellipsoid();
-	Ellipsoid(Name name);
 
 	double radius() const {return _radius;}
 	double flattening() const {return _flattening;}
 
+	bool isNull() const {return _radius < 0 || _flattening < 0;}
+	bool isWGS84() const
+	  {return _radius == WGS84_RADIUS && _flattening == WGS84_FLATTENING;}
+
+	static bool loadList(const QString &path);
+	static const QString &errorString() {return _errorString;}
+	static int errorLine() {return _errorLine;}
+
+	static Ellipsoid ellipsoid(int id);
+
 private:
 	double _radius;
 	double _flattening;
+
+	static QMap<int, Ellipsoid> _ellipsoids;
+	static QString _errorString;
+	static int _errorLine;
 };
 
 #endif // ELLIPSOID_H

src/gui.cpp

@@ -26,6 +26,8 @@
 #include "keys.h"
 #include "settings.h"
 #include "data.h"
+#include "ellipsoid.h"
+#include "datum.h"
 #include "map.h"
 #include "maplist.h"
 #include "mapdir.h"
@@ -47,6 +49,7 @@
 
 GUI::GUI()
 {
+	loadDatums();
 	loadMaps();
 	loadPOIs();
 
@@ -117,6 +120,45 @@ void GUI::createBrowser()
 	_browser->setFilter(filter);
 }
 
+void GUI::loadDatums()
+{
+	QString ef, df;
+
+	if (QFile::exists(USER_ELLIPSOID_FILE))
+		ef = USER_ELLIPSOID_FILE;
+	else if (QFile::exists(GLOBAL_ELLIPSOID_FILE))
+		ef = GLOBAL_ELLIPSOID_FILE;
+	else
+		qWarning("No ellipsoids file found.");
+
+	if (QFile::exists(USER_DATUM_FILE))
+		df = USER_DATUM_FILE;
+	else if (QFile::exists(GLOBAL_DATUM_FILE))
+		df = GLOBAL_DATUM_FILE;
+	else
+		qWarning("No datums file found.");
+
+	if (!ef.isNull() && !df.isNull()) {
+		if (!Ellipsoid::loadList(ef)) {
+			if (Ellipsoid::errorLine())
+				qWarning("%s: parse error on line %d: %s", qPrintable(ef),
+				  Ellipsoid::errorLine(), qPrintable(Ellipsoid::errorString()));
+			else
+				qWarning("%s: %s", qPrintable(ef), qPrintable(
+				  Ellipsoid::errorString()));
+		} else {
+			if (!Datum::loadList(df)) {
+				if (Datum::errorLine())
+					qWarning("%s: parse error on line %d: %s", qPrintable(ef),
+					  Datum::errorLine(), qPrintable(Datum::errorString()));
+				else
+					qWarning("%s: %s", qPrintable(ef), qPrintable(
+					  Datum::errorString()));
+			}
+		}
+	}
+}
+
 void GUI::loadMaps()
 {
 	QList<Map*> online, offline;

src/gui.h

@@ -79,6 +79,7 @@ private slots:
 private:
 	typedef QPair<QDate, QDate> DateRange;
 
+	void loadDatums();
 	void loadMaps();
 	void loadPOIs();
 	void closeFiles();

src/offlinemap.cpp

@@ -12,7 +12,7 @@
 #include "wgs84.h"
 #include "coordinates.h"
 #include "matrix.h"
-#include "ellipsoid.h"
+#include "datum.h"
 #include "latlon.h"
 #include "mercator.h"
 #include "transversemercator.h"
@@ -22,17 +22,39 @@
 #include "offlinemap.h"
 
 
-struct {const char *name; Ellipsoid::Name ellipsoid;} static datums[] = {
+// Abridged Molodensky transformation
-	{"S42", Ellipsoid::Krassowsky1940},
+static Coordinates toWGS84(Coordinates c, const Datum &datum)
-	{"Pulkovo 1942", Ellipsoid::Krassowsky1940},
+{
-	{"European 1950", Ellipsoid::International1924},
+	Ellipsoid WGS84(WGS84_RADIUS, WGS84_FLATTENING);
-	{"European 1979", Ellipsoid::International1924},
+
-	{"NZGD1949", Ellipsoid::International1924},
+	double dX = datum.dx();
-	{"NAD27", Ellipsoid::Clarke1866},
+	double dY = datum.dy();
-	{"NAD83", Ellipsoid::GRS80},
+	double dZ = datum.dz();
-	{"WGS 72", Ellipsoid::WGS72},
+
-	{"South American 1969", Ellipsoid::GRS67}
+	double slat = sin(deg2rad(c.lat()));
-};
+	double clat = cos(deg2rad(c.lat()));
+	double slon = sin(deg2rad(c.lon()));
+	double clon = cos(deg2rad(c.lon()));
+	double ssqlat = slat * slat;
+
+	double from_f = datum.ellipsoid().flattening();
+	double df = WGS84.flattening() - from_f;
+	double from_a = datum.ellipsoid().radius();
+	double da = WGS84.radius() - from_a;
+	double from_esq = datum.ellipsoid().flattening()
+	  * (2.0 - datum.ellipsoid().flattening());
+	double adb = 1.0 / (1.0 - from_f);
+	double rn = from_a / sqrt(1 - from_esq * ssqlat);
+	double rm = from_a * (1 - from_esq) / pow((1 - from_esq * ssqlat), 1.5);
+	double from_h = 0.0; // we're flat!
+
+	double dlat = (-dX * slat * clon - dY * slat * slon + dZ * clat + da * rn
+	  * from_esq * slat * clat / from_a + +df * (rm * adb + rn / adb) * slat
+	  * clat) / (rm + from_h);
+	double dlon = (-dX * slon + dY * clon) / ((rn + from_h) * clat);
+
+	return Coordinates(c.lon() + rad2deg(dlon), c.lat() + rad2deg(dlat));
+}
 
 int OfflineMap::parseMapFile(QIODevice &device, QList<ReferencePoint> &points,
   QString &projection, ProjectionSetup &setup, QString &datum)
@@ -161,32 +183,30 @@ bool OfflineMap::createProjection(const QString &datum,
 		return false;
 	}
 
-	Ellipsoid::Name ellipsoid = Ellipsoid::WGS84;
+	Datum d = Datum::datum(datum);
-	for (size_t i = 0; i < ARRAY_SIZE(datums); i++) {
+	if (d.isNull()) {
-		if (datum.startsWith(datums[i].name)) {
+		qWarning("%s: %s: unknown datum", qPrintable(_name), qPrintable(datum));
-			ellipsoid = datums[i].ellipsoid;
+		return false;
-			break;
-		}
 	}
 
 	if (projection == "Mercator")
 		_projection = new Mercator();
 	else if (projection == "Transverse Mercator")
-		_projection = new TransverseMercator(Ellipsoid(ellipsoid),
+		_projection = new TransverseMercator(d.ellipsoid(),
 		  setup.longitudeOrigin, setup.scale, setup.falseEasting,
 		  setup.falseNorthing);
 	else if (projection == "Latitude/Longitude")
 		_projection = new LatLon();
 	else if (projection == "Lambert Conformal Conic")
-		_projection = new LambertConic(Ellipsoid(ellipsoid),
+		_projection = new LambertConic(d.ellipsoid(),
 		  setup.standardParallel1, setup.standardParallel2,
 		  setup.latitudeOrigin, setup.longitudeOrigin, setup.scale,
 		  setup.falseEasting, setup.falseNorthing);
 	else if (projection == "(UTM) Universal Transverse Mercator") {
 		if (setup.zone)
-			_projection = new UTM(Ellipsoid(ellipsoid), setup.zone);
+			_projection = new UTM(d.ellipsoid(), setup.zone);
 		else if (!points.first().ll.isNull())
-			_projection = new UTM(Ellipsoid(ellipsoid), points.first().ll);
+			_projection = new UTM(d.ellipsoid(), points.first().ll);
 		else {
 			qWarning("%s: Can not determine UTM zone", qPrintable(_name));
 			return false;
@@ -197,9 +217,14 @@ bool OfflineMap::createProjection(const QString &datum,
 		return false;
 	}
 
-	for (int i = 0; i < points.size(); i++)
+	for (int i = 0; i < points.size(); i++) {
-		if (points.at(i).ll.isNull())
+		if (points.at(i).ll.isNull()) {
-			points[i].ll = _projection->xy2ll(points.at(i).pp);
+			if (d.isWGS84())
+				points[i].ll = _projection->xy2ll(points.at(i).pp);
+			else
+				points[i].ll = toWGS84(_projection->xy2ll(points.at(i).pp), d);
+		}
+	}
 
 	return true;
 }