Implement AffineCS and handle it in WKT/PROJJSON

data/projjson.schema.json

@@ -237,6 +237,7 @@
                               "vertical",
                               "ordinal",
                               "parametric",
+                              "affine",
                               "TemporalDateTime",
                               "TemporalCount",
                               "TemporalMeasure"]  },

docs/source/specifications/projjson.rst

@@ -57,6 +57,7 @@ History of the schema
      - Added CoordinateMetadata
      - Added "datum_epoch" property to GeodeticReferenceFrame and VerticalReferenceFrame
      - Added "minimum_value", "maximum_value" and "range_meaning" properties to Axis
+     - Added "affine" in the CoordinateSystem.subtype enumeration.
 * v0.5:
     - Implemented in PROJ 9.1:
         + add "meridian" member in Axis object type.

include/proj/coordinatesystem.hpp

@@ -582,6 +582,56 @@ class PROJ_GCC_DLL CartesianCS final : public CoordinateSystem {
 
 // ---------------------------------------------------------------------------
 
+class AffineCS;
+/** Shared pointer of AffineCS. */
+using AffineCSPtr = std::shared_ptr<AffineCS>;
+/** Non-null shared pointer of AffineCS. */
+using AffineCSNNPtr = util::nn<AffineCSPtr>;
+
+/** \brief A two- or three-dimensional coordinate system in Euclidean space
+ * with straight axes that are not necessarily orthogonal.
+ *
+ * \remark Implements AffineCS from \ref ISO_19111_2019
+ * \since 9.2
+ */
+class PROJ_GCC_DLL AffineCS final : public CoordinateSystem {
+  public:
+    //! @cond Doxygen_Suppress
+    PROJ_DLL ~AffineCS() override;
+    //! @endcond
+
+    PROJ_DLL static AffineCSNNPtr
+    create(const util::PropertyMap &properties,
+           const CoordinateSystemAxisNNPtr &axis1,
+           const CoordinateSystemAxisNNPtr &axis2);
+    PROJ_DLL static AffineCSNNPtr
+    create(const util::PropertyMap &properties,
+           const CoordinateSystemAxisNNPtr &axis1,
+           const CoordinateSystemAxisNNPtr &axis2,
+           const CoordinateSystemAxisNNPtr &axis3);
+
+    PROJ_PRIVATE :
+        //! @cond Doxygen_Suppress
+        PROJ_INTERNAL AffineCSNNPtr
+        alterUnit(const common::UnitOfMeasure &unit) const;
+
+    //! @endcond
+
+  protected:
+    PROJ_INTERNAL explicit AffineCS(
+        const std::vector<CoordinateSystemAxisNNPtr> &axisIn);
+    INLINED_MAKE_SHARED
+
+    PROJ_INTERNAL std::string getWKT2Type(bool) const override {
+        return "affine";
+    }
+
+  private:
+    AffineCS(const AffineCS &other) = delete;
+};
+
+// ---------------------------------------------------------------------------
+
 class OrdinalCS;
 /** Shared pointer of OrdinalCS. */
 using OrdinalCSPtr = std::shared_ptr<OrdinalCS>;

schemas/v0.6/projjson.schema.json

@@ -237,6 +237,7 @@
                               "vertical",
                               "ordinal",
                               "parametric",
+                              "affine",
                               "TemporalDateTime",
                               "TemporalCount",
                               "TemporalMeasure"]  },

scripts/reference_exported_symbols.txt

@@ -198,6 +198,9 @@ osgeo::proj::crs::VerticalCRS::geoidModel() const
 osgeo::proj::crs::VerticalCRS::identify(std::shared_ptr<osgeo::proj::io::AuthorityFactory> const&) const
 osgeo::proj::crs::VerticalCRS::velocityModel() const
 osgeo::proj::crs::VerticalCRS::~VerticalCRS()
+osgeo::proj::cs::AffineCS::~AffineCS()
+osgeo::proj::cs::AffineCS::create(osgeo::proj::util::PropertyMap const&, dropbox::oxygen::nn<std::shared_ptr<osgeo::proj::cs::CoordinateSystemAxis> > const&, dropbox::oxygen::nn<std::shared_ptr<osgeo::proj::cs::CoordinateSystemAxis> > const&)
+osgeo::proj::cs::AffineCS::create(osgeo::proj::util::PropertyMap const&, dropbox::oxygen::nn<std::shared_ptr<osgeo::proj::cs::CoordinateSystemAxis> > const&, dropbox::oxygen::nn<std::shared_ptr<osgeo::proj::cs::CoordinateSystemAxis> > const&, dropbox::oxygen::nn<std::shared_ptr<osgeo::proj::cs::CoordinateSystemAxis> > const&)
 osgeo::proj::cs::AxisDirection::valueOf(std::string const&)
 osgeo::proj::cs::CartesianCS::~CartesianCS()
 osgeo::proj::cs::CartesianCS::createEastingNorthing(osgeo::proj::common::UnitOfMeasure const&)

src/iso19111/coordinatesystem.cpp

@@ -1288,6 +1288,73 @@ CartesianCS::alterUnit(const common::UnitOfMeasure &unit) const {
 
 // ---------------------------------------------------------------------------
 
+//! @cond Doxygen_Suppress
+AffineCS::~AffineCS() = default;
+//! @endcond
+
+// ---------------------------------------------------------------------------
+
+AffineCS::AffineCS(const std::vector<CoordinateSystemAxisNNPtr> &axisIn)
+    : CoordinateSystem(axisIn) {}
+
+// ---------------------------------------------------------------------------
+
+/** \brief Instantiate a AffineCS.
+ *
+ * @param properties See \ref general_properties.
+ * @param axis1 The first axis.
+ * @param axis2 The second axis.
+ * @return a new AffineCS.
+ */
+AffineCSNNPtr AffineCS::create(const util::PropertyMap &properties,
+                               const CoordinateSystemAxisNNPtr &axis1,
+                               const CoordinateSystemAxisNNPtr &axis2) {
+    std::vector<CoordinateSystemAxisNNPtr> axis{axis1, axis2};
+    auto cs(AffineCS::nn_make_shared<AffineCS>(axis));
+    cs->setProperties(properties);
+    return cs;
+}
+
+// ---------------------------------------------------------------------------
+
+/** \brief Instantiate a AffineCS.
+ *
+ * @param properties See \ref general_properties.
+ * @param axis1 The first axis.
+ * @param axis2 The second axis.
+ * @param axis3 The third axis.
+ * @return a new AffineCS.
+ */
+AffineCSNNPtr AffineCS::create(const util::PropertyMap &properties,
+                               const CoordinateSystemAxisNNPtr &axis1,
+                               const CoordinateSystemAxisNNPtr &axis2,
+                               const CoordinateSystemAxisNNPtr &axis3) {
+    std::vector<CoordinateSystemAxisNNPtr> axis{axis1, axis2, axis3};
+    auto cs(AffineCS::nn_make_shared<AffineCS>(axis));
+    cs->setProperties(properties);
+    return cs;
+}
+
+// ---------------------------------------------------------------------------
+
+//! @cond Doxygen_Suppress
+AffineCSNNPtr AffineCS::alterUnit(const common::UnitOfMeasure &unit) const {
+    const auto &l_axisList = CoordinateSystem::getPrivate()->axisList;
+    if (l_axisList.size() == 2) {
+        return AffineCS::create(util::PropertyMap(),
+                                l_axisList[0]->alterUnit(unit),
+                                l_axisList[1]->alterUnit(unit));
+    } else {
+        assert(l_axisList.size() == 3);
+        return AffineCS::create(
+            util::PropertyMap(), l_axisList[0]->alterUnit(unit),
+            l_axisList[1]->alterUnit(unit), l_axisList[2]->alterUnit(unit));
+    }
+}
+//! @endcond
+
+// ---------------------------------------------------------------------------
+
 //! @cond Doxygen_Suppress
 OrdinalCS::~OrdinalCS() = default;
 //! @endcond

src/iso19111/io.cpp

@@ -2940,7 +2940,8 @@ WKTParser::Private::buildCS(const WKTNodeNNPtr &node, /* maybe null */
                   : ci_equal(csType, "parametric")
                         ? UnitOfMeasure::Type::PARAMETRIC
                         : ci_equal(csType, "Cartesian") ||
-                                  ci_equal(csType, "vertical")
+                                  ci_equal(csType, "vertical") ||
+                                  ci_equal(csType, "affine")
                               ? UnitOfMeasure::Type::LINEAR
                               : (ci_equal(csType, "temporal") ||
                                  ci_equal(csType, "TemporalDateTime") ||
@@ -2972,6 +2973,13 @@ WKTParser::Private::buildCS(const WKTNodeNNPtr &node, /* maybe null */
             return CartesianCS::create(csMap, axisList[0], axisList[1],
                                        axisList[2]);
         }
+    } else if (ci_equal(csType, "affine")) {
+        if (axisCount == 2) {
+            return AffineCS::create(csMap, axisList[0], axisList[1]);
+        } else if (axisCount == 3) {
+            return AffineCS::create(csMap, axisList[0], axisList[1],
+                                    axisList[2]);
+        }
     } else if (ci_equal(csType, "vertical")) {
         if (axisCount == 1) {
             return VerticalCS::create(csMap, axisList[0]);
@@ -6635,6 +6643,16 @@ CoordinateSystemNNPtr JSONParser::buildCS(const json &j) {
         }
         throw ParsingException("Expected 2 or 3 axis");
     }
+    if (subtype == "affine") {
+        if (axisCount == 2) {
+            return AffineCS::create(csMap, axisList[0], axisList[1]);
+        }
+        if (axisCount == 3) {
+            return AffineCS::create(csMap, axisList[0], axisList[1],
+                                    axisList[2]);
+        }
+        throw ParsingException("Expected 2 or 3 axis");
+    }
     if (subtype == "vertical") {
         if (axisCount == 1) {
             return VerticalCS::create(csMap, axisList[0]);

test/unit/test_io.cpp

@@ -2979,6 +2979,30 @@ TEST(wkt_parse, vdatum_with_ANCHOREPOCH) {
 
 // ---------------------------------------------------------------------------
 
+TEST(wkt_parse, engineeringCRS_WKT2_affine_CS) {
+
+    auto wkt = "ENGCRS[\"Engineering CRS\",\n"
+               "    EDATUM[\"Engineering datum\"],\n"
+               "    CS[affine,2],\n"
+               "        AXIS[\"(E)\",east,\n"
+               "            ORDER[1],\n"
+               "            LENGTHUNIT[\"metre\",1,\n"
+               "                ID[\"EPSG\",9001]]],\n"
+               "        AXIS[\"(N)\",north,\n"
+               "            ORDER[2],\n"
+               "            LENGTHUNIT[\"metre\",1,\n"
+               "                ID[\"EPSG\",9001]]]]";
+
+    auto obj = WKTParser().createFromWKT(wkt);
+    auto crs = nn_dynamic_pointer_cast<EngineeringCRS>(obj);
+    ASSERT_TRUE(crs != nullptr);
+    EXPECT_EQ(crs->exportToWKT(
+                  WKTFormatter::create(WKTFormatter::Convention::WKT2).get()),
+              wkt);
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(wkt_parse, COMPOUNDCRS) {
     auto obj = WKTParser().createFromWKT(
         "COMPOUNDCRS[\"horizontal + vertical\",\n"
@@ -15599,6 +15623,43 @@ TEST(json_import, engineering_crs) {
 
 // ---------------------------------------------------------------------------
 
+TEST(json_import, engineering_crs_affine_CS) {
+
+    auto json = "{\n"
+                "  \"$schema\": \"foo\",\n"
+                "  \"type\": \"EngineeringCRS\",\n"
+                "  \"name\": \"myEngCRS\",\n"
+                "  \"datum\": {\n"
+                "    \"name\": \"myEngDatum\"\n"
+                "  },\n"
+                "  \"coordinate_system\": {\n"
+                "    \"subtype\": \"affine\",\n"
+                "    \"axis\": [\n"
+                "      {\n"
+                "        \"name\": \"Easting\",\n"
+                "        \"abbreviation\": \"E\",\n"
+                "        \"direction\": \"east\",\n"
+                "        \"unit\": \"metre\"\n"
+                "      },\n"
+                "      {\n"
+                "        \"name\": \"Northing\",\n"
+                "        \"abbreviation\": \"N\",\n"
+                "        \"direction\": \"north\",\n"
+                "        \"unit\": \"metre\"\n"
+                "      }\n"
+                "    ]\n"
+                "  }\n"
+                "}";
+
+    auto obj = createFromUserInput(json, nullptr);
+    auto crs = nn_dynamic_pointer_cast<EngineeringCRS>(obj);
+    ASSERT_TRUE(crs != nullptr);
+    EXPECT_EQ(crs->exportToJSON(&(JSONFormatter::create()->setSchema("foo"))),
+              json);
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(json_import, temporal_crs) {
     auto json = "{\n"
                 "  \"$schema\": \"foo\",\n"