Assorted set of fixes for PROJString to ISO19111 model:

- createFromPROJString(): take into account axisswap step for Krovak and Transverse Mercator (South Orientated)
- Geocentric export to PROJ4: use datum when possible, and add explicit units=m
- ESRI WKT parser: make it case insensitive to parameter and projection names, and more tolerant about possible parameter name aliases
- import from WKT1 for Polar_Stereographic: don't be case sensitive
- importFromPROJString: allow pm to override datum
- Equidistant cylindrical: add support for non-standard latitude of natural origin, used in a GDAL test case
- tmerc export to PROJString: use 'k' instead of 'k_0'
- pj_ellps: use official value from EPSG for reverse flattening of Airy ellipsoid
- GDAL compatibility: add support for importing odd formulations of Mercator as WKT1, but rejecting them when exporting to PROJ
- Add export of 'Geostationary Satellite (Sweep X)' to WKT1_GDAL via EXTENSION.PROJ4 node
- importFromPROJString: add support for +f
- WKT1 / PROJ4: add support for EXTENSION.PROJ4 nodes and +wktext
- exportToWKT: change way we deal with AXIS by default for WKT1_GDAL
- Improve etmerc handling
- Fix WKT import of peg_point_heading for Spherical_Cross_Track_Height
- International Map of the World Polyconic: change parameter mapping
- exportToPROJ: add alpha parameter
- Hotine_Oblique_Mercator_Two_Point_Natural_Origin: GDAL_WKT1 related fix
- GDAL compatibility improvements in import from PROJ4 / WKT1 for polar stereographic
- Add support for +towgs84 when importing a +proj=geocent
- import from WKT1: add support for an odd Mercator_1SP formulation handled by GDAL
- export to proj4 strings: add +units=m to projected CRS for better GDAL compatibility
- export to proj4 strings: add +no_defs to CRS for better GDAL compatibility

include/proj/coordinateoperation.hpp

@@ -497,6 +497,7 @@ class PROJ_GCC_DLL OperationMethod : public common::IdentifiedObject {
     PROJ_INTERNAL OperationMethod();
     PROJ_INTERNAL OperationMethod(const OperationMethod &other);
     INLINED_MAKE_SHARED
+    friend class Conversion;
 
   private:
     PROJ_OPAQUE_PRIVATE_DATA
@@ -1296,7 +1297,7 @@ class PROJ_GCC_DLL Conversion : public SingleOperation {
     INLINED_MAKE_SHARED
 
     PROJ_FRIEND(crs::ProjectedCRS);
-    PROJ_INTERNAL void addWKTExtensionNode(io::WKTFormatter *formatter) const;
+    PROJ_INTERNAL bool addWKTExtensionNode(io::WKTFormatter *formatter) const;
 
   private:
     PROJ_OPAQUE_PRIVATE_DATA

include/proj/crs.hpp

@@ -472,7 +472,7 @@ class PROJ_GCC_DLL DerivedCRS : virtual public SingleCRS {
 
     PROJ_PRIVATE :
         //! @cond Doxygen_Suppress
-        const operation::ConversionNNPtr &
+        PROJ_INTERNAL const operation::ConversionNNPtr &
         derivingConversionRef() PROJ_CONST_DECL;
     //! @endcond
 

include/proj/internal/coordinateoperation_constants.hpp

@@ -88,6 +88,11 @@ static const ParamMapping paramScaleFactor = {
     EPSG_CODE_PARAMETER_SCALE_FACTOR_AT_NATURAL_ORIGIN, WKT1_SCALE_FACTOR,
     common::UnitOfMeasure::Type::SCALE, k_0};
 
+static const ParamMapping paramScaleFactorK = {
+    EPSG_NAME_PARAMETER_SCALE_FACTOR_AT_NATURAL_ORIGIN,
+    EPSG_CODE_PARAMETER_SCALE_FACTOR_AT_NATURAL_ORIGIN, WKT1_SCALE_FACTOR,
+    common::UnitOfMeasure::Type::SCALE, k};
+
 static const ParamMapping paramFalseEasting = {
     EPSG_NAME_PARAMETER_FALSE_EASTING, EPSG_CODE_PARAMETER_FALSE_EASTING,
     WKT1_FALSE_EASTING, common::UnitOfMeasure::Type::LINEAR, x_0};
@@ -130,6 +135,10 @@ static const ParamMapping *const paramsNatOriginScale[] = {
     &paramLatitudeNatOrigin, &paramLongitudeNatOrigin, &paramScaleFactor,
     &paramFalseEasting,      &paramFalseNorthing,      nullptr};
 
+static const ParamMapping *const paramsNatOriginScaleK[] = {
+    &paramLatitudeNatOrigin, &paramLongitudeNatOrigin, &paramScaleFactorK,
+    &paramFalseEasting,      &paramFalseNorthing,      nullptr};
+
 static const ParamMapping paramLatFirstPoint = {
     "Latitude of 1st point", 0, "Latitude_Of_1st_Point",
     common::UnitOfMeasure::Type::ANGULAR, lat_1};
@@ -243,9 +252,11 @@ static const ParamMapping *const paramsEQDC[] = {&paramLatNatLatCenter,
 static const ParamMapping *const paramsLonNatOrigin[] = {
     &paramLongitudeNatOrigin, &paramFalseEasting, &paramFalseNorthing, nullptr};
 
-static const ParamMapping *const paramsEqc[] = // same as paramsCEA
-    {&paramLat1stParallelLatTs, &paramLongitudeNatOrigin, &paramFalseEasting,
-     &paramFalseNorthing, nullptr};
+static const ParamMapping *const paramsEqc[] = {
+    &paramLat1stParallelLatTs,
+    &paramLatitudeNatOrigin, // extension of EPSG, but used by GDAL / PROJ
+    &paramLongitudeNatOrigin,  &paramFalseEasting,
+    &paramFalseNorthing,       nullptr};
 
 static const ParamMapping paramSatelliteHeight = {
     "Satellite Height", 0, "satellite_height",
@@ -331,7 +342,7 @@ static const ParamMapping paramLonPoint2 = {
     common::UnitOfMeasure::Type::ANGULAR, lon_2};
 
 static const ParamMapping *const paramsHomTwoPoint[] = {
-    &paramLatCentreLatOrigin,
+    &paramLatCentreLatCenter,
     &paramLatPoint1,
     &paramLonPoint1,
     &paramLatPoint2,
@@ -342,9 +353,8 @@ static const ParamMapping *const paramsHomTwoPoint[] = {
     nullptr};
 
 static const ParamMapping *const paramsIMWP[] = {
-    &paramLongitudeNatOrigin,     &paramLatitude1stStdParallel,
-    &paramLatitude2ndStdParallel, &paramFalseEasting,
-    &paramFalseNorthing,          nullptr};
+    &paramLongitudeNatOrigin, &paramLatFirstPoint, &paramLatSecondPoint,
+    &paramFalseEasting,       &paramFalseNorthing, nullptr};
 
 static const ParamMapping paramLonCentreLonCenter = {
     EPSG_NAME_PARAMETER_LONGITUDE_OF_ORIGIN,
@@ -355,7 +365,7 @@ static const ParamMapping paramColatitudeConeAxis = {
     EPSG_NAME_PARAMETER_COLATITUDE_CONE_AXIS,
     EPSG_CODE_PARAMETER_COLATITUDE_CONE_AXIS, WKT1_AZIMUTH,
     common::UnitOfMeasure::Type::ANGULAR,
-    nullptr}; /* ignored by PROJ currently */
+    "alpha"}; /* ignored by PROJ currently */
 
 static const ParamMapping paramLatitudePseudoStdParallel = {
     EPSG_NAME_PARAMETER_LATITUDE_PSEUDO_STANDARD_PARALLEL,
@@ -393,11 +403,6 @@ static const ParamMapping paramLatMerc1SP = {
     common::UnitOfMeasure::Type::ANGULAR,
     nullptr}; // always set to zero, not to be exported in PROJ strings
 
-static const ParamMapping paramScaleFactorK = {
-    EPSG_NAME_PARAMETER_SCALE_FACTOR_AT_NATURAL_ORIGIN,
-    EPSG_CODE_PARAMETER_SCALE_FACTOR_AT_NATURAL_ORIGIN, WKT1_SCALE_FACTOR,
-    common::UnitOfMeasure::Type::SCALE, k};
-
 static const ParamMapping *const paramsMerc1SP[] = {
     &paramLatMerc1SP,   &paramLongitudeNatOrigin, &paramScaleFactorK,
     &paramFalseEasting, &paramFalseNorthing,      nullptr};
@@ -492,12 +497,12 @@ static const ParamMapping *const paramsLabordeObliqueMercator[] = {
 
 static const MethodMapping methodMappings[] = {
     {EPSG_NAME_METHOD_TRANSVERSE_MERCATOR, EPSG_CODE_METHOD_TRANSVERSE_MERCATOR,
-     "Transverse_Mercator", "tmerc", nullptr, paramsNatOriginScale},
+     "Transverse_Mercator", "tmerc", nullptr, paramsNatOriginScaleK},
 
     {EPSG_NAME_METHOD_TRANSVERSE_MERCATOR_SOUTH_ORIENTATED,
      EPSG_CODE_METHOD_TRANSVERSE_MERCATOR_SOUTH_ORIENTATED,
      "Transverse_Mercator_South_Orientated", "tmerc", "axis=wsu",
-     paramsNatOriginScale},
+     paramsNatOriginScaleK},
 
     {PROJ_WKT2_NAME_METHOD_TWO_POINT_EQUIDISTANT, 0, "Two_Point_Equidistant",
      "tpeqd", nullptr, paramsTPEQD},
@@ -605,7 +610,7 @@ static const MethodMapping methodMappings[] = {
     {PROJ_WKT2_NAME_METHOD_INTERRUPTED_GOODE_HOMOLOSINE, 0,
      "Interrupted_Goode_Homolosine", "igh", nullptr, paramsLonNatOrigin},
 
-    // No WKT1 representation fr sweep=x
+    // No proper WKT1 representation fr sweep=x
     {PROJ_WKT2_NAME_METHOD_GEOSTATIONARY_SATELLITE_SWEEP_X, 0, nullptr, "geos",
      "sweep=x", paramsGeos},
 

include/proj/internal/coordinateoperation_internal.hpp

@@ -70,6 +70,8 @@ const ParamMapping *getMapping(const MethodMapping *mapping,
                                const OperationParameterValue *param);
 const ParamMapping *getMappingFromWKT1(const MethodMapping *mapping,
                                        const std::string &wkt1_name);
+bool areEquivalentParameters(const std::string &a, const std::string &b);
+
 // ---------------------------------------------------------------------------
 
 struct ESRIParamMapping {

include/proj/internal/internal.hpp

@@ -125,6 +125,8 @@ inline bool starts_with(const std::string &str, const char *prefix) noexcept {
     return std::memcmp(str.c_str(), prefix, prefixSize) == 0;
 }
 
+bool ci_less(const std::string &a, const std::string &b) noexcept;
+
 bool ci_starts_with(const char *str, const char *prefix) noexcept;
 
 bool ci_starts_with(const std::string &str, const std::string &prefix) noexcept;

include/proj/io.hpp

@@ -206,7 +206,19 @@ class PROJ_GCC_DLL WKTFormatter {
 
     PROJ_DLL WKTFormatter &setMultiLine(bool multiLine) noexcept;
     PROJ_DLL WKTFormatter &setIndentationWidth(int width) noexcept;
-    PROJ_DLL WKTFormatter &setOutputAxis(bool outputAxis) noexcept;
+
+    /** Rule for output AXIS nodes */
+    enum class OutputAxisRule {
+        /** Always include AXIS nodes */
+        YES,
+        /** Never include AXIS nodes */
+        NO,
+        /** Includes them only on PROJCS node if it uses Easting/Northing
+         *ordering. Typically used for WKT1_GDAL */
+        WKT1_GDAL_EPSG_STYLE,
+    };
+
+    PROJ_DLL WKTFormatter &setOutputAxis(OutputAxisRule outputAxis) noexcept;
     PROJ_DLL WKTFormatter &setStrict(bool strict) noexcept;
     PROJ_DLL bool isStrict() const noexcept;
 
@@ -273,7 +285,7 @@ class PROJ_GCC_DLL WKTFormatter {
     PROJ_INTERNAL bool isInverted() const;
 #endif
 
-    PROJ_INTERNAL bool outputAxis() const;
+    PROJ_INTERNAL OutputAxisRule outputAxis() const;
     PROJ_INTERNAL bool outputAxisOrder() const;
     PROJ_INTERNAL bool primeMeridianOmittedIfGreenwich() const;
     PROJ_INTERNAL bool ellipsoidUnitOmittedIfMetre() const;
@@ -352,7 +364,7 @@ class PROJ_GCC_DLL PROJStringFormatter {
         startInversion();
     PROJ_DLL void stopInversion();
     PROJ_INTERNAL bool isInverted() const;
-    PROJ_INTERNAL bool getUseETMercForTMerc() const;
+    PROJ_INTERNAL bool getUseETMercForTMerc(bool &settingSetOut) const;
 
     PROJ_DLL void
     ingestPROJString(const std::string &str); // throw ParsingException
@@ -373,6 +385,11 @@ class PROJ_GCC_DLL PROJStringFormatter {
     PROJ_DLL void addParam(const char *paramName,
                            const std::vector<double> &vals);
 
+    PROJ_INTERNAL bool hasParam(const char *paramName) const;
+
+    PROJ_INTERNAL void addNoDefs(bool b);
+    PROJ_INTERNAL bool getAddNoDefs() const;
+
     PROJ_INTERNAL std::set<std::string> getUsedGridNames() const;
 
     PROJ_INTERNAL void setTOWGS84Parameters(const std::vector<double> &params);

src/c_api.cpp

@@ -839,7 +839,10 @@ static const char *getOptionValue(const char *option,
  * <li>MULTILINE=YES/NO. Defaults to YES, except for WKT1_ESRI</li>
  * <li>INDENTATION_WIDTH=number. Defauls to 4 (when multiline output is
  * on).</li>
- * <li>OUTPUT_AXIS=YES/NO. Defaults to YES, except for WKT1_ESRI.</li>
+ * <li>OUTPUT_AXIS=AUTO/YES/NO. In AUTO mode, axis will be output for WKT2
+ * variants, for WKT1_GDAL for ProjectedCRS with easting/northing ordering
+ * (otherwise stripped), but not for WKT1_ESRI. Setting to YES will output
+ * them unconditionaly, and to NO will omit them unconditionaly.</li>
  * </ul>
  * @return a string, or NULL in case of error.
  */
@@ -890,7 +893,12 @@ const char *proj_obj_as_wkt(PJ_OBJ *obj, PJ_WKT_TYPE type,
             } else if ((value = getOptionValue(*iter, "INDENTATION_WIDTH="))) {
                 formatter->setIndentationWidth(std::atoi(value));
             } else if ((value = getOptionValue(*iter, "OUTPUT_AXIS="))) {
-                formatter->setOutputAxis(ci_equal(value, "YES"));
+                if (!ci_equal(value, "AUTO")) {
+                    formatter->setOutputAxis(
+                        ci_equal(value, "YES")
+                            ? WKTFormatter::OutputAxisRule::YES
+                            : WKTFormatter::OutputAxisRule::NO);
+                }
             } else {
                 std::string msg("Unknown option :");
                 msg += *iter;
@@ -925,7 +933,8 @@ const char *proj_obj_as_wkt(PJ_OBJ *obj, PJ_WKT_TYPE type,
  * @param options NULL-terminated list of strings with "KEY=VALUE" format. or
  * NULL.
  * The currently recognized option is USE_ETMERC=YES to use
- * +proj=etmerc instead of +proj=tmerc
+ * +proj=etmerc instead of +proj=tmerc (or USE_ETMERC=NO to disable implicit
+ * use of etmerc by utm conversions)
  * @return a string, or NULL in case of error.
  */
 const char *proj_obj_as_proj_string(PJ_OBJ *obj, PJ_PROJ_STRING_TYPE type,
@@ -960,6 +969,8 @@ const char *proj_obj_as_proj_string(PJ_OBJ *obj, PJ_PROJ_STRING_TYPE type,
         if (options != nullptr && options[0] != nullptr) {
             if (ci_equal(options[0], "USE_ETMERC=YES")) {
                 formatter->setUseETMercForTMerc(true);
+            } else if (ci_equal(options[0], "USE_ETMERC=NO")) {
+                formatter->setUseETMercForTMerc(false);
             }
         }
         obj->lastPROJString = exportable->exportToPROJString(formatter.get());