From 425c3ca579e17c5f6d6534c1acd853c569e62ab3 Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Tue, 11 Jul 2023 23:48:53 +0200
Subject: [PATCH] exportToPROJString(): when a NADCON operation is included in
 a vertical transformation, do not include axis swap

---
 src/iso19111/operation/singleoperation.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/iso19111/operation/singleoperation.cpp b/src/iso19111/operation/singleoperation.cpp
index fa529cbf7c..276213f67c 100644
--- a/src/iso19111/operation/singleoperation.cpp
+++ b/src/iso19111/operation/singleoperation.cpp
@@ -3730,9 +3730,11 @@ bool SingleOperation::exportToPROJStringGeneric(
                 concat("Can apply ", methodName, " only to GeographicCRS"));
         }
 
-        formatter->startInversion();
-        sourceCRSGeog->addAngularUnitConvertAndAxisSwap(formatter);
-        formatter->stopInversion();
+        if (!formatter->omitHorizontalConversionInVertTransformation()) {
+            formatter->startInversion();
+            sourceCRSGeog->addAngularUnitConvertAndAxisSwap(formatter);
+            formatter->stopInversion();
+        }
 
         if (isMethodInverseOf) {
             formatter->startInversion();
@@ -3753,7 +3755,9 @@ bool SingleOperation::exportToPROJStringGeneric(
             formatter->stopInversion();
         }
 
-        targetCRSGeog->addAngularUnitConvertAndAxisSwap(formatter);
+        if (!formatter->omitHorizontalConversionInVertTransformation()) {
+            targetCRSGeog->addAngularUnitConvertAndAxisSwap(formatter);
+        }
 
         return true;
     }