Merge pull request #2861 from rouault/optimize_pipelines_planetary_crs

Optimize pipelines of planetary CRS (geocentric latitude, west-positive longitude)

3 files changed, 42 insertions, 4 deletions

diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index 598cedad..a12c6aa0 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -2073,8 +2073,16 @@ void GeodeticCRS::_exportToPROJString(
         addGeocentricUnitConversionIntoPROJString(formatter);
     } else if (isSphericalPlanetocentric()) {
         if (!formatter->getCRSExport()) {
-            formatter->addStep("geoc");
-            addDatumInfoToPROJString(formatter);
+
+            if (!formatter->omitProjLongLatIfPossible() ||
+                primeMeridian()->longitude().getSIValue() != 0.0 ||
+                !ellipsoid()->isSphere() ||
+                !formatter->getTOWGS84Parameters().empty() ||
+                !formatter->getHDatumExtension().empty()) {
+                formatter->addStep("geoc");
+                addDatumInfoToPROJString(formatter);
+            }
+
             addAngularUnitConvertAndAxisSwap(formatter);
         } else {
             io::FormattingException::Throw(
diff --git a/src/iso19111/io.cpp b/src/iso19111/io.cpp
index d3928a86..b317213a 100644
--- a/src/iso19111/io.cpp
+++ b/src/iso19111/io.cpp
@@ -7509,13 +7509,22 @@ const std::string &PROJStringFormatter::toString() const {
 
         const auto paramCount = step.paramValues.size();
 
-        // axisswap order=2,1 is its own inverse
+        // axisswap order=2,1 (or 1,-2) is its own inverse
         if (step.name == "axisswap" && paramCount == 1 &&
-            step.paramValues[0].equals("order", "2,1")) {
+            (step.paramValues[0].equals("order", "2,1") ||
+             step.paramValues[0].equals("order", "1,-2"))) {
             step.inverted = false;
             continue;
         }
 
+        // axisswap inv order=2,-1 ==> axisswap order -2,1
+        if (step.name == "axisswap" && paramCount == 1 &&
+            step.paramValues[0].equals("order", "2,-1")) {
+            step.inverted = false;
+            step.paramValues[0] = Step::KeyValue("order", "-2,1");
+            continue;
+        }
+
         // handle unitconvert inverse
         if (step.name == "unitconvert" && paramCount == 2 &&
             step.paramValues[0].keyEquals("xy_in") &&
@@ -7790,6 +7799,25 @@ const std::string &PROJStringFormatter::toString() const {
                 continue;
             }
 
+            // axisswap order=2,1 followed by axisswap order=2,-1 is
+            // equivalent to axisswap order=1,-2
+            // Same for axisswap order=-2,1 followed by axisswap order=2,1
+            if (curStep.name == "axisswap" && prevStep.name == "axisswap" &&
+                curStepParamCount == 1 && prevStepParamCount == 1 &&
+                ((prevStep.paramValues[0].equals("order", "2,1") &&
+                  !curStep.inverted &&
+                  curStep.paramValues[0].equals("order", "2,-1")) ||
+                 (prevStep.paramValues[0].equals("order", "-2,1") &&
+                  !prevStep.inverted &&
+                  curStep.paramValues[0].equals("order", "2,1")))) {
+
+                prevStep.inverted = false;
+                prevStep.paramValues[0] = Step::KeyValue("order", "1,-2");
+                // Delete this iter
+                iterCur = steps.erase(iterCur);
+                continue;
+            }
+
             // axisswap order=2,1, unitconvert, axisswap order=2,1 -> can
             // suppress axisswap
             if (std::next(iterCur) != steps.end() &&
diff --git a/src/iso19111/operation/conversion.cpp b/src/iso19111/operation/conversion.cpp
index f7bb8ec8..3db62a7d 100644
--- a/src/iso19111/operation/conversion.cpp
+++ b/src/iso19111/operation/conversion.cpp
@@ -3534,11 +3534,13 @@ void Conversion::_exportToPROJString(
             if ((isSrcGeocentricLat && isTargetGeographic) ||
                 (isSrcGeographic && isTargetGeocentricLat)) {
 
+                formatter->setOmitProjLongLatIfPossible(true);
                 formatter->startInversion();
                 sourceCRSGeod->_exportToPROJString(formatter);
                 formatter->stopInversion();
 
                 targetCRSGeod->_exportToPROJString(formatter);
+                formatter->setOmitProjLongLatIfPossible(false);
 
                 return;
             }