Use WGS84 (G2139) as the geographic CRS

src/core/georeferencing.h

@@ -47,35 +47,47 @@ namespace OpenOrienteering {
 
 
 /**
- * A utility which encapsulates PROJ API variants and resource management.
+ * Utilities which encapsulate PROJ API variants and resource management.
  */
+struct ProjCRS
+{
+	ProjCRS(const ProjCRS&) = delete;
+	ProjCRS(ProjCRS&& other) noexcept;
+	ProjCRS(const QString& crs_spec);
+	~ProjCRS();
+
+	ProjCRS& operator=(const ProjCRS& other) = delete;
+	ProjCRS& operator=(ProjCRS&& other) noexcept;
+
+	bool isValid() const noexcept;
+	bool isGeographic() const;
+private:
+	ProjTransformData* pj = nullptr;
+
+	friend struct ProjTransform;
+};
+
 struct ProjTransform
 {
-	ProjTransform() noexcept = default;
+	ProjTransform() noexcept;
 	ProjTransform(const ProjTransform&) = delete;
 	ProjTransform(ProjTransform&& other) noexcept;
-	ProjTransform(const QString& crs_spec);
+	ProjTransform(const QString& crs_spec, const QString& geographic_crs_spec);
 	~ProjTransform();
 
 	ProjTransform& operator=(const ProjTransform& other) = delete;
 	ProjTransform& operator=(ProjTransform&& other) noexcept;
 
-	/// Create a PROJ CRS object.
-	static ProjTransform crs(const QString& crs_spec);
-
 	bool isValid() const noexcept;
-	bool isGeographic() const;
 
 	QPointF forward(const LatLon& lat_lon, bool* ok) const;
 	LatLon inverse(const QPointF& projected, bool* ok) const;
 
 	QString errorText() const;
 
 private:
-	ProjTransform(ProjTransformData* pj) noexcept;
-
 	ProjTransformData* pj = nullptr;
-
+	ProjCRS geographic_crs;
 };
 
 
@@ -133,7 +145,7 @@ friend QDebug operator<<(QDebug dbg, const Georeferencing& georef);
 	/**
 	 * A shared PROJ specification of a WGS84 geographic CRS.
 	 */
-	static const QString geographic_crs_spec;
+	static const QString ballpark_geographic_crs_spec;
 
 
 	/**
@@ -427,6 +439,38 @@ friend QDebug operator<<(QDebug dbg, const Georeferencing& georef);
 	 */
 	bool setProjectedCRS(const QString& id, QString spec, std::vector< QString > params = std::vector<QString>());
 
+	/** 
+	 * Returns the specification of the WGS84-based geographic coordinate
+	 * reference system (CRS) used by Georeferencing.
+	 * This is the target CRS of the toGeographicCoords methods,
+	 * and also the source CRS when applicable.
+	 * @return a PROJ specification of the geographic CRS
+	 */
+	const QString& getGeographicCRSSpec() const { return realization_crs_spec.isEmpty()
+	                                                     ? ballpark_geographic_crs_spec
+	                                                     : realization_crs_spec; }
+
+	/** 
+	 * Returns whether transformations use loose accuracy around the WGS84
+	 * datum for explicitly requested compatibility with older releases of Mapper.
+	 * @return true if transformations are set compatible, false otherwise
+	 */
+	bool isDatumBallpark() const { return explicit_realization && realization_crs_spec.isEmpty(); }
+
+	/**
+	 * Sets the coordinate reference system (CRS) of the geographical coordinates,
+	 * to either the ballpark CRS or the GNSS CRS.
+	 *
+	 * This setting determines the "pivot" coordinates used to transform one pair
+	 * of projected coordinates to another, also the transformation of map
+	 * coordinates to geographical, also transformation of GNSS coordinates to
+	 * map coordinates.
+	 *
+	 * @param ballpark whether to make the datum "ballpark", otherwise make it a realization of WGS84
+	 * @return true if the resulting transformation is valid, false otherwise
+	 */
+	bool setDatumBallpark(bool ballpark);
+
 	/**
 	 * Calculates the convergence at the reference point.
 	 * 
@@ -480,7 +524,8 @@ friend QDebug operator<<(QDebug dbg, const Georeferencing& georef);
 	LatLon toGeographicCoords(const MapCoordF& map_coords, bool* ok = 0) const;
 
 	/**
-	 * Transforms CRS coordinates to geographic coordinates (lat/lon).
+	 * Transforms CRS coordinates to geographic coordinates (lat/lon)
+	 * using a WGS84 datum.
 	 */
 	LatLon toGeographicCoords(const QPointF& projected_coords, bool* ok = 0) const;
 
@@ -632,6 +677,11 @@ friend QDebug operator<<(QDebug dbg, const Georeferencing& georef);
 	void setScaleFactors(double combined_scale_factor, double auxiliary_scale_factor);
 	void setDeclinationAndGrivation(double declination, double grivation);
 
+	/**
+	 * PROJ specification of an accurate realization of the WGS84 geographic CRS.
+	 */
+	static const QString gnss_crs_spec;
+
 	State state;
 
 	unsigned int scale_denominator;
@@ -672,6 +722,9 @@ friend QDebug operator<<(QDebug dbg, const Georeferencing& georef);
 	QString projected_crs_id;
 	QString projected_crs_spec;
 	std::vector< QString > projected_crs_parameters;
+
+	QString realization_crs_spec;
+	bool explicit_realization;
 
 	ProjTransform proj_transform;
 

src/fileformats/xml_file_format.cpp

@@ -719,6 +719,15 @@ void XMLFileImporter::validateGeoreferencing()
 	auto const& loaded_georef = map->getGeoreferencing();
 	if (loaded_georef.getState() != Georeferencing::Geospatial)
 		return;
+
+	// Check for 'is_realization' not set.
+	if (!loaded_georef.isDatumBallpark()
+		&& Georeferencing::ballpark_geographic_crs_spec == loaded_georef.getGeographicCRSSpec())
+	{
+		addWarning(tr("This map was saved by an older version of Mapper, "
+					  "with less accurate template alignment.\n\n"
+					  "Adjust Georeferencing to confirm or change."));
+	}
 
 	// Check for georeferencings with inconsistent declination/grivation,
 	// e.g. from GH-1206 (georef setup bug)

src/gdal/ogr_file_format.cpp

@@ -1338,6 +1338,22 @@ bool OgrFileImport::setSRS(OGRSpatialReferenceH srs)
 	if (srs && data_srs != srs)
 	{
 		// New SRS, indeed.
+		auto& georef = map->getGeoreferencing();
+		if (OSRIsGeographic(srs) && !georef.isDatumBallpark())
+		{
+			auto ballpark_srs = ogr::unique_srs { OSRNewSpatialReference(nullptr) };
+			OSRSetWellKnownGeogCS(ballpark_srs.get(), "WGS84");
+
+			if (!strcmp(OSRGetAuthorityName(srs, nullptr), OSRGetAuthorityName(ballpark_srs.get(), nullptr))
+				&& !strcmp(OSRGetAuthorityCode(srs, nullptr), OSRGetAuthorityCode(ballpark_srs.get(), nullptr)))
+			{
+				// Substitute an accurate, recent realization of WGS84.
+				auto gnss_srs = ogr::unique_srs { OSRNewSpatialReference(nullptr) };
+				OSRSetWellKnownGeogCS(gnss_srs.get(), georef.getGeographicCRSSpec().toUtf8());
+				OSRCopyGeogCSFrom(srs, gnss_srs.get());
+			}
+		}
+
 		auto transformation = ogr::unique_transformation{ OCTNewCoordinateTransformation(srs, map_srs.get()) };
 		if (!transformation)
 		{

src/gdal/ogr_template.cpp

@@ -296,7 +296,7 @@ try
 		{
 			is_georeferenced = true;
 			// Data is to be transformed to the map CRS directly.
-			track_crs_spec = Georeferencing::geographic_crs_spec;
+			track_crs_spec = georef.getGeographicCRSSpec();
 			return true;
 		}
 	}
@@ -318,7 +318,7 @@ try
 			preserveRefPoints(*data_georef, initial_georef);
 		explicit_georef = std::move(data_georef);
 		// Data is to be transformed to the projected CRS.
-		track_crs_spec = Georeferencing::geographic_crs_spec;
+		track_crs_spec = explicit_georef->getGeographicCRSSpec();
 		projected_crs_spec = explicit_georef->getProjectedCRSSpec();
 	}
 
@@ -600,7 +600,7 @@ bool OgrTemplate::finishTypeSpecificTemplateConfiguration()
 			// Data is to be transformed to the map CRS directly.
 			Q_ASSERT(projected_crs_spec.isEmpty());
 		}
-		else if (!track_crs_spec.contains(QLatin1String("+proj=latlong")))
+		else if (!ProjCRS(track_crs_spec).isGeographic())
 		{
 			// Nothing to do with this configuration
 			Q_ASSERT(projected_crs_spec.isEmpty());

src/gui/map/map_editor.cpp

@@ -2370,6 +2370,26 @@ void MapEditorController::showTagsWindow(bool show)
 
 void MapEditorController::editGeoreferencing()
 {
+	// Check for 'is_realization' not set.
+	const Georeferencing& georef = getMap()->getGeoreferencing();
+	if (georef.getState() == Georeferencing::Geospatial
+		&& !georef.isDatumBallpark()
+		&& Georeferencing::ballpark_geographic_crs_spec == georef.getGeographicCRSSpec())
+	{
+		auto message =
+		        tr("This map was saved by an older version of Mapper, "
+		           "with less accurate template alignment.\n\n"
+		           "Press Yes for more accurate alignment.\n"
+		           "Press No to retain template alignment.");
+		int result = QMessageBox::question(getWindow(), tr("Warning"), message, QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel, QMessageBox::Yes);
+		if (QMessageBox::Yes == result || QMessageBox::No == result)
+		{
+			auto local_georef = Georeferencing(georef);
+			local_georef.setDatumBallpark(QMessageBox::No == result);
+			map->setGeoreferencing(local_georef);
+		}
+	}
+
 	if (georeferencing_dialog.isNull())
 	{
 		auto* dialog = new GeoreferencingDialog(this); 

src/gui/select_crs_dialog.cpp

@@ -101,7 +101,7 @@ SelectCRSDialog::SelectCRSDialog(
 		crs_selector->setCurrentIndex(crs_selector->findData(SpecialCRS::TemplateFile));
 	else if (crs_spec == georef.getProjectedCRSSpec())
 		crs_selector->setCurrentIndex(crs_selector->findData(SpecialCRS::SameAsMap));
-	else if (crs_spec == Georeferencing::geographic_crs_spec)
+	else if (crs_spec == georef.getGeographicCRSSpec())
 		crs_selector->setCurrentIndex(crs_selector->findData(SpecialCRS::Geographic));
 	else
 		crs_selector->setCurrentCRS(CRSTemplateRegistry().find(QString::fromLatin1("PROJ.4")), { crs_spec });
@@ -130,7 +130,7 @@ QString SelectCRSDialog::currentCRSSpec() const
 		// nothing
 		break;
 	case SpecialCRS::Geographic:
-		spec = Georeferencing::geographic_crs_spec;
+		spec = georef.getGeographicCRSSpec();
 		break;
 	case SpecialCRS::TemplateFile:
 		spec = options.template_file.crs_spec;

src/templates/template_track.cpp

@@ -152,7 +152,7 @@ TemplateTrack::TemplateTrack(const QString& path, Map* map)
  : Template(path, map)
 {
 	// set default value
-	track_crs_spec = Georeferencing::geographic_crs_spec;
+	track_crs_spec = Georeferencing::ballpark_geographic_crs_spec;
 
 	const Georeferencing& georef = map->getGeoreferencing();
 	connect(&georef, &Georeferencing::projectionChanged, this, &TemplateTrack::updateGeoreferencing);
@@ -257,7 +257,7 @@ bool TemplateTrack::loadTemplateFileImpl()
 		return false;
 	}
 
-	if (!track_crs_spec.isEmpty() && track_crs_spec != Georeferencing::geographic_crs_spec)
+	if (!track_crs_spec.isEmpty() && track_crs_spec != Georeferencing::ballpark_geographic_crs_spec)
 	{
 		setErrorString(tr("This template must be loaded with GDAL/OGR."));
 		return false;
@@ -580,7 +580,7 @@ void TemplateTrack::configureForGPSTrack()
 {
 	is_georeferenced = true;
 
-	track_crs_spec = Georeferencing::geographic_crs_spec;
+	track_crs_spec = Georeferencing::ballpark_geographic_crs_spec;
 
 	projected_crs_spec.clear();
 	track.changeMapGeoreferencing(map->getGeoreferencing());

test/data/templates/geotiff.xmap

@@ -9,6 +9,7 @@
         </projected_crs>
         <geographic_crs id="Geographic coordinates">
             <spec language="PROJ.4">+proj=latlong +datum=WGS84</spec>
+            <realization_spec language="PROJ.4">EPSG:9057</realization_spec>
             <ref_point_deg lat="51.3793253" lon="21.15318339"/>
         </geographic_crs>
     </georeferencing>

test/data/templates/ogr-template.xmap

@@ -9,6 +9,7 @@
         </projected_crs>
         <geographic_crs id="Geographic coordinates">
             <spec language="PROJ.4">+proj=latlong +datum=WGS84</spec>
+            <realization_spec language="PROJ.4">EPSG:9057</realization_spec>
             <ref_point_deg lat="51.3793253" lon="21.15318339"/>
         </geographic_crs>
     </georeferencing>

test/data/templates/template-track-NA-ballpark-GDAL.xmap

@@ -0,0 +1,65 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<map xmlns="http://openorienteering.org/apps/mapper/xml/v2" version="9">
+    <notes></notes>
+    <georeferencing scale="4000" auxiliary_scale_factor="1.0004" declination="8" grivation="8">
+        <projected_crs id="EPSG">
+            <spec language="PROJ.4">+init=epsg:6342</spec>
+            <parameter>6342</parameter>
+            <ref_point x="500000" y="4430000"/>
+        </projected_crs>
+        <geographic_crs id="Geographic coordinates">
+            <spec language="PROJ.4">+proj=latlong +datum=WGS84</spec>
+            <realization_spec/>
+            <ref_point_deg lat="40.02021349" lon="-105.00001013"/>
+        </geographic_crs>
+    </georeferencing>
+    <colors count="1">
+        <color priority="0" name="Purple" c="0.2" m="1" y="0" k="0" opacity="1">
+            <spotcolors>
+                <namedcolor>PURPLE</namedcolor>
+            </spotcolors>
+            <cmyk method="custom"/>
+            <rgb method="cmyk" r="0.8" g="0" b="1"/>
+        </color>
+    </colors>
+    <barrier version="6" required="0.6.0">
+        <symbols count="1">
+            <symbol type="2" id="0" code="1" name="Line">
+                <line_symbol color="0" line_width="100" minimum_length="0" join_style="1" cap_style="0" start_offset="0" end_offset="0" segment_length="4000" end_length="0" show_at_least_one_symbol="true" minimum_mid_symbol_count="0" minimum_mid_symbol_count_when_closed="0" dash_length="4000" break_length="1000" dashes_in_group="1" in_group_break_length="500" mid_symbols_per_spot="1" mid_symbol_distance="0"/>
+            </symbol>
+        </symbols>
+        <parts count="1" current="0">
+            <part name="default part">
+                <objects count="1">
+                    <object type="1" symbol="0">
+                        <coords count="5">
+                            <coord x="-158217" y="170205"/>
+                            <coord x="-157505" y="175272"/>
+                            <coord x="-150981" y="174356"/>
+                            <coord x="-151693" y="169288"/>
+                            <coord x="-158217" y="170205" flags="18"/>
+                        </coords>
+                        <pattern rotation="0">
+                            <coord x="0" y="0"/>
+                        </pattern>
+                    </object>
+                </objects>
+            </part>
+        </parts>
+        <templates count="1" first_front_template="1">
+            <template type="OgrTemplate" open="true" name="template-track-NA-2019.gpx" path="template-track-NA-2019.gpx" relpath="template-track-NA-2019.gpx" georef="true">
+                <crs_spec>+proj=latlong +datum=WGS84</crs_spec>
+            </template>
+            <defaults use_meters_per_pixel="true" meters_per_pixel="0" dpi="0" scale="0"/>
+        </templates>
+        <view>
+            <grid color="#646464" display="0" alignment="1" additional_rotation="0" unit="0" h_spacing="0.1" v_spacing="0.1" h_offset="0" v_offset="0" snapping_enabled="true"/>
+            <map_view zoom="32" position_x="-154564" position_y="171849">
+                <map opacity="1" visible="true"/>
+                <templates count="1">
+                    <ref template="0" visible="true" opacity="1"/>
+                </templates>
+            </map_view>
+        </view>
+    </barrier>
+</map>

test/data/templates/template-track-NA.xmap

@@ -9,6 +9,7 @@
         </projected_crs>
         <geographic_crs id="Geographic coordinates">
             <spec language="PROJ.4">+proj=latlong +datum=WGS84</spec>
+            <realization_spec language="PROJ.4">EPSG:9057</realization_spec>
             <ref_point_deg lat="40.02021349" lon="-105.00001013"/>
         </geographic_crs>
     </georeferencing>

test/data/templates/template-track.xmap

@@ -9,6 +9,7 @@
         </projected_crs>
         <geographic_crs id="Geographic coordinates">
             <spec language="PROJ.4">+proj=latlong +datum=WGS84</spec>
+            <realization_spec language="PROJ.4">EPSG:9057</realization_spec>
             <ref_point_deg lat="51.3793253" lon="21.15318339"/>
         </geographic_crs>
     </georeferencing>

test/data/templates/world-file.xmap

@@ -9,6 +9,7 @@
         </projected_crs>
         <geographic_crs id="Geographic coordinates">
             <spec language="PROJ.4">+proj=latlong +datum=WGS84</spec>
+            <realization_spec language="PROJ.4">EPSG:9057</realization_spec>
             <ref_point_deg lat="51.3793253" lon="21.15318339"/>
         </geographic_crs>
     </georeferencing>

test/file_format_t.cpp

@@ -227,6 +227,7 @@ namespace
 		QCOMPARE(actual_georef.getProjectedCRSName(), expected_georef.getProjectedCRSName());
 		QCOMPARE(actual_georef.getProjectedCoordinatesName(), expected_georef.getProjectedCoordinatesName());
 		QCOMPARE(actual_georef.getProjectedCRSSpec(), expected_georef.getProjectedCRSSpec());
+		QCOMPARE(actual_georef.getGeographicCRSSpec(), expected_georef.getGeographicCRSSpec());
 		QVERIFY(qAbs(actual_georef.getGeographicRefPoint().latitude() - expected_georef.getGeographicRefPoint().latitude()) < 0.5e-8);
 		QVERIFY(qAbs(actual_georef.getGeographicRefPoint().longitude() - expected_georef.getGeographicRefPoint().longitude()) < 0.5e-8);