Merge pull request #743 from kbevers/fix-nullgrid-datumtransform

Handle ellipsoid parameters correctly when using +nadgrids=@null.
OSGeo · Jan 23, 2018 · 29cb4a0 · 29cb4a0
2 parents 33a7216 + d0dbf48
commit 29cb4a0
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Showing 2 changed files with 22 additions and 9 deletions.
diff --git a/nad/proj_outIGNF.dist b/nad/proj_outIGNF.dist
@@ -1,16 +1,16 @@
 +init=./IGNF:NTFG +to +init=./IGNF:RGF93G
  3.300866856 43.4477976569 0.0000	3d18'0.915"E	43d26'52.077"N 0.000
 +init=./IGNF:LAMBE +to +init=./IGNF:LAMB93
- 600000.0000 2600545.4523  0.0000	652760.737	7033791.243 0.000
+ 600000.0000 2600545.4523  0.0000	652760.737	7033791.244 0.000
  135638.3592 2418760.4094  0.0000	187194.062	6855928.882 0.000
  998137.3947 2413822.2844  0.0000	1049052.258	6843776.562 0.000
- 600000.0000 2200000.0000  0.0000	649398.872	6633524.191 0.000
+ 600000.0000 2200000.0000  0.0000	649398.872	6633524.192 0.000
  311552.5340 1906457.4840  0.0000	358799.172	6342652.486 0.000
  960488.4138 1910172.8812  0.0000	1007068.686	6340907.237 0.000
  600000.0000 1699510.8340  0.0000	645204.279	6133556.746 0.000
-1203792.5981 626873.17210  0.0000	1238875.764	5057405.016 0.000
+1203792.5981 626873.17210  0.0000	1238875.764	5057405.017 0.000
 +init=./IGNF:LAMBE +to +init=./IGNF:GEOPORTALFXX
- 600000.0000 2600545.4523  0.0000	179040.148	5610495.275 0.000
+ 600000.0000 2600545.4523  0.0000	179040.148	5610495.276 0.000
  135638.3592 2418760.4094  0.0000	-303729.363	5410118.356 0.000
  998137.3947 2413822.2844  0.0000	592842.792	5410120.554 0.000
  600000.0000 2200000.0000  0.0000	179041.670	5209746.080 0.000
@@ -37,4 +37,4 @@
 2d20'11.7754730" 42d18'00.0824436" 0.0	260109.601	5009175.714 0.000
 9d32'12.6680218" 41d24'00.3542556" 0.0	1061637.534	4889066.592 0.000
 +init=./IGNF:RGR92 +to +init=./IGNF:REUN47
-3356123.5400 1303218.3090 5247430.6050	3353421.833	1304074.314 5248935.607
+3356123.5400 1303218.3090 5247430.6050	3353421.833	1304074.314 5248935.606
diff --git a/src/pj_transform.c b/src/pj_transform.c
@@ -748,17 +748,30 @@ int pj_datum_transform( PJ *srcdefn, PJ *dstdefn,
 /* -------------------------------------------------------------------- */
     if( srcdefn->datum_type == PJD_GRIDSHIFT )
     {
+        const char* srcnadgrids = pj_param(srcdefn->ctx, srcdefn->params,"snadgrids").s;
+
         pj_apply_gridshift_2( srcdefn, 0, point_count, point_offset, x, y, z );
         CHECK_RETURN(srcdefn);
 
-        src_a = SRS_WGS84_SEMIMAJOR;
-        src_es = SRS_WGS84_ESQUARED;
+        /* If the gridlist has either "@null" or "null" as its only    */
+        /* grid we don't change the ellipsoid parameters, since the    */
+        /* datum shift to WGS84 was not performed in practice.         */
+        if ( strcmp("@null", srcnadgrids) && strcmp("null", srcnadgrids) ) {
+            src_a = SRS_WGS84_SEMIMAJOR;
+            src_es = SRS_WGS84_ESQUARED;
+        }
     }
 
     if( dstdefn->datum_type == PJD_GRIDSHIFT )
     {
-        dst_a = SRS_WGS84_SEMIMAJOR;
-        dst_es = SRS_WGS84_ESQUARED;
+        const char* dstnadgrids = pj_param(dstdefn->ctx, dstdefn->params,"snadgrids").s;
+        /* If the gridlist has either "@null" or "null" as its only    */
+        /* grid we don't change the ellipsoid parameters, since the    */
+        /* datum shift to WGS84 will not be performed.                 */
+        if ( strcmp("@null", dstnadgrids) && strcmp("null", dstnadgrids) ) {
+            dst_a = SRS_WGS84_SEMIMAJOR;
+            dst_es = SRS_WGS84_ESQUARED;
+          }
     }
 
 /* ==================================================================== */