ProjectedCRS::_isEquivalentTo(): ignore base CRS axis order even in EQUIVALENT mode if one of them is lacking an explicit CS order (refs #2886)

2 files changed, 31 insertions, 0 deletions

diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index b48f0d70..731bf7f9 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -4171,6 +4171,17 @@ ProjectedCRS::create(const util::PropertyMap &properties,
 bool ProjectedCRS::_isEquivalentTo(
     const util::IComparable *other, util::IComparable::Criterion criterion,
     const io::DatabaseContextPtr &dbContext) const {
+    auto otherProjCRS = dynamic_cast<const ProjectedCRS *>(other);
+    if (otherProjCRS != nullptr &&
+        criterion == util::IComparable::Criterion::EQUIVALENT &&
+        (d->baseCRS_->hasImplicitCS() ||
+         otherProjCRS->d->baseCRS_->hasImplicitCS())) {
+        // If one of the 2 base CRS has implicit coordinate system, then
+        // relax the check. The axis order of the base CRS doesn't matter
+        // for most purposes.
+        criterion =
+            util::IComparable::Criterion::EQUIVALENT_EXCEPT_AXIS_ORDER_GEOGCRS;
+    }
     return other != nullptr && util::isOfExactType<ProjectedCRS>(*other) &&
            DerivedCRS::_isEquivalentTo(other, criterion, dbContext);
 }
diff --git a/test/unit/test_crs.cpp b/test/unit/test_crs.cpp
index bc42d834..a1838896 100644
--- a/test/unit/test_crs.cpp
+++ b/test/unit/test_crs.cpp
@@ -6707,3 +6707,23 @@ TEST(crs, projected_alterParametersLinearUnit_do_not_mess_deriving_conversion) {
     }
     EXPECT_EQ(projCRS->derivingConversion()->targetCRS().get(), projCRS.get());
 }
+
+// ---------------------------------------------------------------------------
+
+TEST(crs, projected_is_equivalent_to_with_proj4_extension) {
+    const auto obj1 = PROJStringParser().createFromPROJString(
+        "+proj=omerc +lat_0=50 +alpha=50.0 +no_rot +a=6378144.0 +b=6356759.0 "
+        "+lon_0=8.0 +type=crs");
+    const auto crs1 = nn_dynamic_pointer_cast<ProjectedCRS>(obj1);
+    ASSERT_TRUE(crs1 != nullptr);
+
+    const auto wkt = crs1->exportToWKT(
+        WKTFormatter::create(WKTFormatter::Convention::WKT2_2019).get());
+    const auto obj_from_wkt = WKTParser().createFromWKT(wkt);
+    const auto crs_from_wkt =
+        nn_dynamic_pointer_cast<ProjectedCRS>(obj_from_wkt);
+
+    // Check equivalence of the CRS from PROJ.4 and WKT
+    EXPECT_TRUE(crs1->isEquivalentTo(crs_from_wkt.get(),
+                                     IComparable::Criterion::EQUIVALENT));
+}