PROJ string ingestion: adds +towgs84= when expanding +init=epsg:XXXX (f…

…ixes OSGeo#1597) Currently, +init=epsg:XXXX expansion from proj.db didn't make any effort to try to add a +towgs84 clause. Now this will do using CRS::createBoundCRSToWGS84IfPossible() Note that however this does not perfectly emulated PROJ4/PROJ5 epsg file behaviour, and will only add a +towgs84 when it is valid for the whole area of use of the CRS, whereas PROJ4/PROJ5 would add the one that was valid for the largest sub-area of use. The additiong of a +towgs84 clause will be thus more likely for a projected CRS valid for a country, rather than for a geographic CRS valid for a continent or a larger area, and thus whose transformations to WGS84 might be multiple. The consequence of this shows up in some GIGS test that must be adapted to add an explicit +towgs84 for source/target geographic CRS with value equal to the one of the source/target projected CRS.
rouault · Sep 11, 2019 · 18c553a · 18c553a
1 parent 9fea5bf
commit 18c553a
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Showing 6 changed files with 37 additions and 16 deletions.
diff --git a/src/init.cpp b/src/init.cpp
@@ -38,6 +38,7 @@
 
 #include "geodesic.h"
 #include "proj.h"
+#include "proj_experimental.h"
 #include "proj_internal.h"
 #include "proj_math.h"
 
@@ -289,8 +290,12 @@ Expand key from buffer or (if not in buffer) from init file
                 return nullptr;
             }
 
-            proj_string = proj_as_proj_string(ctx, src, PJ_PROJ_4, nullptr);
+            auto boundCRS = proj_crs_create_bound_crs_to_WGS84(ctx, src, nullptr);
+
+            proj_string = proj_as_proj_string(ctx, boundCRS ? boundCRS : src, PJ_PROJ_4, nullptr);
+
             if( !proj_string ) {
+                proj_destroy(boundCRS);
                 proj_destroy(src);
                 return nullptr;
             }
@@ -299,6 +304,7 @@ Expand key from buffer or (if not in buffer) from init file
                 strcpy(definition, proj_string);
             }
 
+            proj_destroy(boundCRS);
             proj_destroy(src);
         }
     }

diff --git a/src/iso19111/io.cpp b/src/iso19111/io.cpp
@@ -8821,8 +8821,23 @@ PROJStringParser::createFromPROJString(const std::string &projString) {
                         }
                     }
                     expanded += ' ';
-                    expanded += projStringExportable->exportToPROJString(
-                        PROJStringFormatter::create().get());
+
+                    auto boundToWGS84 = crs->createBoundCRSToWGS84IfPossible(
+                        d->dbContext_,
+                        CoordinateOperationContext::IntermediateCRSUse::NEVER);
+                    auto projStringExportableBoundToWGS84 =
+                        dynamic_cast<IPROJStringExportable *>(
+                            boundToWGS84.get());
+                    if (projStringExportableBoundToWGS84) {
+                        expanded +=
+                            projStringExportableBoundToWGS84
+                                ->exportToPROJString(
+                                    PROJStringFormatter::create().get());
+                    } else {
+                        expanded += projStringExportable->exportToPROJString(
+                            PROJStringFormatter::create().get());
+                    }
+
                     return createFromPROJString(expanded);
                 }
             }

diff --git a/test/gigs/5102.1.gie b/test/gigs/5102.1.gie
@@ -10,7 +10,7 @@ use_proj4_init_rules true
 
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
-           +step +init=epsg:4230 +inv
+           +step +init=epsg:4230 +towgs84=-84,-97,-117,0,0,0,0 +inv
            +step +init=epsg:2192
 --------------------------------------------------------------------------------
 tolerance  0.03 m
@@ -92,7 +92,7 @@ expect    1183924.412 2923146.858
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
            +step +init=epsg:2192 +inv
-           +step +init=epsg:4230
+           +step +init=epsg:4230 +towgs84=-84,-97,-117,0,0,0,0
 --------------------------------------------------------------------------------
 tolerance  0.03 m
 accept    760722.92 3457368.68
@@ -172,7 +172,7 @@ expect    11 53
 
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
-           +step +init=epsg:4230 +inv
+           +step +init=epsg:4230 +towgs84=-84,-97,-117,0,0,0,0 +inv
            +step +init=epsg:2192
 --------------------------------------------------------------------------------
 tolerance  0.006 m

diff --git a/test/gigs/5103.1.gie b/test/gigs/5103.1.gie
@@ -10,7 +10,7 @@ use_proj4_init_rules true
 
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
-           +step +init=epsg:4313 +inv
+           +step +init=epsg:4313 +towgs84=-99.059,53.322,-112.486,0.419,-0.83,1.885,-1 +inv
            +step +init=epsg:31370
 
 tolerance  30 mm
@@ -47,7 +47,7 @@ expect    123101.889 -34711.068
 
 accept    3.3137281 47.9752611
 expect    71254.553 -148236.592
-
++init=epsg:4313
 accept    3 53
 expect    58108.966 411155.591
 
@@ -79,7 +79,7 @@ expect    595117.95 430202.63
 --------------------------------------------------------------------------------
 operation  proj=pipeline
            step init=epsg:31370 inv
-           step init=epsg:4313
+           step init=epsg:4313 towgs84=-99.059,53.322,-112.486,0.419,-0.83,1.885,-1
 
 tolerance  30 mm
 --------------------------------------------------------------------------------
@@ -145,7 +145,7 @@ expect    11 53
 
 --------------------------------------------------------------------------------
 operation  +proj=pipeline   towgs84=0,0,0   # turn off dual datum shift
-           +step +init=epsg:4313 +inv
+           +step +init=epsg:4313 +towgs84=-99.059,53.322,-112.486,0.419,-0.83,1.885,-1 +inv
            +step +init=epsg:31370
 
 tolerance  6 mm

diff --git a/test/gigs/5105.2.gie b/test/gigs/5105.2.gie
@@ -10,7 +10,7 @@ use_proj4_init_rules true
 
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
-           +step +init=epsg:4237 +inv
+           +step +init=epsg:4237 +towgs84=52.684,-71.194,-13.975,-0.312,-0.1063,-0.3729,1.0191 +inv
            +step +init=epsg:23700
 --------------------------------------------------------------------------------
 tolerance  0.05 m
@@ -64,7 +64,7 @@ expect    439836.709 20816.456
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
            +step +init=epsg:23700 +inv
-           +step +init=epsg:4237
+           +step +init=epsg:4237 +towgs84=52.684,-71.194,-13.975,-0.312,-0.1063,-0.3729,1.0191
 --------------------------------------------------------------------------------
 tolerance  0.05 m
 accept    424714.235 355124.6
@@ -116,7 +116,7 @@ expect    16.36 45.5
 
 --------------------------------------------------------------------------------
 operation  +proj=pipeline
-           +step +init=epsg:4237 +inv
+           +step +init=epsg:4237 +towgs84=52.684,-71.194,-13.975,-0.312,-0.1063,-0.3729,1.0191 +inv
            +step +init=epsg:23700
 --------------------------------------------------------------------------------
 tolerance  0.006 m

diff --git a/test/gigs/5112.gie b/test/gigs/5112.gie
@@ -10,7 +10,7 @@ use_proj4_init_rules true
 
 --------------------------------------------------------------------------------
 operation  proj=pipeline
-           step init=epsg:4284 inv
+           step init=epsg:4284 towgs84=25,-141,-78.5,0,0.35,0.736,0 inv
            step init=epsg:3388
 
 tolerance 50 mm
@@ -33,7 +33,7 @@ expect    1325634.35 -3709687.25
 --------------------------------------------------------------------------------
 operation  proj=pipeline
            step init=epsg:3388 inv
-           step init=epsg:4284
+           step init=epsg:4284 towgs84=25,-141,-78.5,0,0.35,0.736,0
 
 tolerance 50 mm
 --------------------------------------------------------------------------------
@@ -54,7 +54,7 @@ expect    67.0 -41.0
 
 --------------------------------------------------------------------------------
 operation proj=pipeline towgs84=0,0,0
-          step init=epsg:4284 inv
+          step init=epsg:4284 towgs84=25,-141,-78.5,0,0.35,0.736,0 inv
           step init=epsg:3388
 
 tolerance 6 mm