Geographic 3D CRS: allow to export to WKT1:ESRI if only the GEOGCS is known (and thus extrapolating a VERTCS) (fixes #2757)

1 files changed, 32 insertions, 4 deletions

diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index 0d157da1..575f6e2b 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -1850,11 +1850,39 @@ static bool exportAsESRIWktCompoundCRSWithEllipsoidalHeight(
     auto vertCRSList = authFactory->createVerticalCRSFromDatum(
         "ESRI", "from_geogdatum_" + *gdatum_ids[0]->codeSpace() + '_' +
                     gdatum_ids[0]->code());
-    if (vertCRSList.size() != 1) {
-        return false;
-    }
     self->demoteTo2D(std::string(), dbContext)->_exportToWKT(formatter);
-    vertCRSList.front()->_exportToWKT(formatter);
+    if (vertCRSList.size() == 1) {
+        vertCRSList.front()->_exportToWKT(formatter);
+    } else {
+        // This will not be recognized properly by ESRI software
+        // See https://github.com/OSGeo/PROJ/issues/2757
+
+        const auto &axisList = geodCRS->coordinateSystem()->axisList();
+        assert(axisList.size() == 3U);
+
+        formatter->startNode(io::WKTConstants::VERTCS, false);
+        auto vertcs_name = l_esri_name;
+        if (starts_with(vertcs_name.c_str(), "GCS_"))
+            vertcs_name = vertcs_name.substr(4);
+        formatter->addQuotedString(vertcs_name);
+
+        gdatum->_exportToWKT(formatter);
+
+        // Seems to be a constant value...
+        formatter->startNode(io::WKTConstants::PARAMETER, false);
+        formatter->addQuotedString("Vertical_Shift");
+        formatter->add(0.0);
+        formatter->endNode();
+
+        formatter->startNode(io::WKTConstants::PARAMETER, false);
+        formatter->addQuotedString("Direction");
+        formatter->add(
+            axisList[2]->direction() == cs::AxisDirection::UP ? 1.0 : -1.0);
+        formatter->endNode();
+
+        axisList[2]->unit()._exportToWKT(formatter);
+        formatter->endNode();
+    }
     return true;
 }