1 files changed, 43 insertions, 0 deletions
diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index 5d2c6d7b..573dd6db 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -1620,6 +1620,34 @@ static bool exportAsESRIWktCompoundCRSWithEllipsoidalHeight(
     vertCRSList.front()->_exportToWKT(formatter);
     return true;
 }
+
+// ---------------------------------------------------------------------------
+
+// Try to format a Geographic/ProjectedCRS 3D CRS as a
+// GEOGCS[]/PROJCS[],VERTCS["Ellipsoid (metre)",DATUM["Ellipsoid",2002],...]
+static bool exportAsWKT1CompoundCRSWithEllipsoidalHeight(
+    const CRSNNPtr &base2DCRS,
+    const cs::CoordinateSystemAxisNNPtr &verticalAxis,
+    io::WKTFormatter *formatter) {
+    std::string verticalCRSName = "Ellipsoid (";
+    verticalCRSName += verticalAxis->unit().name();
+    verticalCRSName += ')';
+    auto vertDatum = datum::VerticalReferenceFrame::create(
+        util::PropertyMap()
+            .set(common::IdentifiedObject::NAME_KEY, "Ellipsoid")
+            .set("VERT_DATUM_TYPE", "2002"));
+    auto vertCRS = VerticalCRS::create(
+        util::PropertyMap().set(common::IdentifiedObject::NAME_KEY,
+                                verticalCRSName),
+        vertDatum.as_nullable(), nullptr,
+        cs::VerticalCS::create(util::PropertyMap(), verticalAxis));
+    formatter->startNode(io::WKTConstants::COMPD_CS, false);
+    formatter->addQuotedString(base2DCRS->nameStr() + " + " + verticalCRSName);
+    base2DCRS->_exportToWKT(formatter);
+    vertCRS->_exportToWKT(formatter);
+    formatter->endNode();
+    return true;
+}
 //! @endcond
 
 // ---------------------------------------------------------------------------
@@ -1687,6 +1715,13 @@ void GeodeticCRS::_exportToWKT(io::WKTFormatter *formatter) const {
             return;
         }
 
+        if (formatter->isAllowedEllipsoidalHeightAsVerticalCRS()) {
+            if (exportAsWKT1CompoundCRSWithEllipsoidalHeight(
+                    geogCRS2D, axisList[2], formatter)) {
+                return;
+            }
+        }
+
         io::FormattingException::Throw(
             "WKT1 does not support Geographic 3D CRS.");
     }
@@ -3640,6 +3675,14 @@ void ProjectedCRS::_exportToWKT(io::WKTFormatter *formatter) const {
             return;
         }
 
+        if (!formatter->useESRIDialect() &&
+            formatter->isAllowedEllipsoidalHeightAsVerticalCRS()) {
+            if (exportAsWKT1CompoundCRSWithEllipsoidalHeight(
+                    projCRS2D, axisList[2], formatter)) {
+                return;
+            }
+        }
+
         io::FormattingException::Throw(
             "Projected 3D CRS can only be exported since WKT2:2019");
     }