Add VERTCON grid name alternatives in database, and handle filename substitution for VERTCON method

3 files changed, 106 insertions, 0 deletions

diff --git a/data/sql/grid_alternatives.sql b/data/sql/grid_alternatives.sql
index a45c43f1..99f20d0e 100644
--- a/data/sql/grid_alternatives.sql
+++ b/data/sql/grid_alternatives.sql
@@ -142,6 +142,53 @@ INSERT INTO grid_alternatives(original_grid_name,
                               'proj-datumgrid-europe',
                               NULL, NULL, NULL, NULL);
 
+-- Continental USA VERTCON: NGVD (19)29 height to NAVD (19)88 height
+
+INSERT INTO grid_alternatives(original_grid_name,
+                              proj_grid_name,
+                              proj_grid_format,
+                              proj_method,
+                              inverse_direction,
+                              package_name,
+                              url, direct_download, open_license, directory)
+                      VALUES ('vertconw.94',
+                              'vertconw.gtx',
+                              'GTX',
+                              'vgridshift',
+                              0,
+                              'proj-datumgrid-north-america',
+                              NULL, NULL, NULL, NULL);
+
+INSERT INTO grid_alternatives(original_grid_name,
+                              proj_grid_name,
+                              proj_grid_format,
+                              proj_method,
+                              inverse_direction,
+                              package_name,
+                              url, direct_download, open_license, directory)
+                      VALUES ('vertconc.94',
+                              'vertconc.gtx',
+                              'GTX',
+                              'vgridshift',
+                              0,
+                              'proj-datumgrid-north-america',
+                              NULL, NULL, NULL, NULL);
+
+INSERT INTO grid_alternatives(original_grid_name,
+                              proj_grid_name,
+                              proj_grid_format,
+                              proj_method,
+                              inverse_direction,
+                              package_name,
+                              url, direct_download, open_license, directory)
+                      VALUES ('vertcone.94',
+                              'vertcone.gtx',
+                              'GTX',
+                              'vgridshift',
+                              0,
+                              'proj-datumgrid-north-america',
+                              NULL, NULL, NULL, NULL);
+
 -- EGM models
 
 INSERT INTO grid_alternatives(original_grid_name,
diff --git a/src/iso19111/coordinateoperation.cpp b/src/iso19111/coordinateoperation.cpp
index 2128124b..90266307 100644
--- a/src/iso19111/coordinateoperation.cpp
+++ b/src/iso19111/coordinateoperation.cpp
@@ -8001,6 +8001,46 @@ TransformationNNPtr Transformation::substitutePROJAlternativeGridNames(
         }
     }
 
+    if (methodEPSGCode == EPSG_CODE_METHOD_VERTCON) {
+        auto fileParameter =
+            parameterValue(EPSG_NAME_PARAMETER_VERTICAL_OFFSET_FILE,
+                           EPSG_CODE_PARAMETER_VERTICAL_OFFSET_FILE);
+        if (fileParameter &&
+            fileParameter->type() == ParameterValue::Type::FILENAME) {
+
+            auto filename = fileParameter->valueFile();
+            if (databaseContext->lookForGridAlternative(
+                    filename, projFilename, projGridFormat, inverseDirection)) {
+
+                if (filename == projFilename) {
+                    assert(!inverseDirection);
+                    return self;
+                }
+
+                auto parameters = std::vector<OperationParameterNNPtr>{
+                    createOpParamNameEPSGCode(
+                        EPSG_CODE_PARAMETER_VERTICAL_OFFSET_FILE)};
+                if (inverseDirection) {
+                    return create(createPropertiesForInverse(
+                                      self.as_nullable().get(), true, false),
+                                  targetCRS(), sourceCRS(), nullptr,
+                                  createSimilarPropertiesMethod(method()),
+                                  parameters, {ParameterValue::createFilename(
+                                                  projFilename)},
+                                  coordinateOperationAccuracies())
+                        ->inverseAsTransformation();
+                } else {
+                    return create(
+                        createSimilarPropertiesTransformation(self),
+                        sourceCRS(), targetCRS(), nullptr,
+                        createSimilarPropertiesMethod(method()), parameters,
+                        {ParameterValue::createFilename(projFilename)},
+                        coordinateOperationAccuracies());
+                }
+            }
+        }
+    }
+
     return self;
 }
 // ---------------------------------------------------------------------------
diff --git a/test/unit/test_operation.cpp b/test/unit/test_operation.cpp
index 90deb661..58b740b6 100644
--- a/test/unit/test_operation.cpp
+++ b/test/unit/test_operation.cpp
@@ -6174,6 +6174,25 @@ TEST(operation, vertCRS_to_vertCRS) {
 
 // ---------------------------------------------------------------------------
 
+TEST(operation, vertCRS_to_vertCRS_context) {
+    auto authFactory =
+        AuthorityFactory::create(DatabaseContext::create(), "EPSG");
+    auto ctxt = CoordinateOperationContext::create(authFactory, nullptr, 0.0);
+    ctxt->setSpatialCriterion(
+        CoordinateOperationContext::SpatialCriterion::PARTIAL_INTERSECTION);
+    auto list = CoordinateOperationFactory::create()->createOperations(
+        // NGVD29 height (m)
+        authFactory->createCoordinateReferenceSystem("7968"),
+        // NAVD88 height (1)
+        authFactory->createCoordinateReferenceSystem("5703"), ctxt);
+    ASSERT_EQ(list.size(), 3U);
+    EXPECT_EQ(list[0]->nameStr(), "NGVD29 height (m) to NAVD88 height (3)");
+    EXPECT_EQ(list[0]->exportToPROJString(PROJStringFormatter::create().get()),
+              "+proj=vgridshift +grids=vertcone.gtx +multiplier=0.001");
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(operation, compoundCRS_to_geogCRS_3D) {
 
     auto compoundcrs_ft_obj = PROJStringParser().createFromPROJString(