[MapServer-users] how to perform a two step transformation

[Travis Kirstine]

Hi all,

I'm trying to figure out how to set up a transformation pipeline in
MapServer where I apply a grid shift.  Any ideas

Step 1 UTM z17 NAD83 CSRS (EPSG:2958) to UTM z17 NAD83 Original
(EPSG:26917).

Example using cs2cs
cs2cs +init=epsg:2958 +to +proj=utm +zone=17 +datum=NAD83
+nadgrids=./ON83CSv1.gsb  -v -E -I
# ---- From Coordinate System ----
+proj=utm +zone=17 +datum=NAD83 +nadgrids=./ON83CSv1.gsb
# ---- To Coordinate System ----
+init=epsg:2958
500000 4500000
500000 4500000  500000.15       4499999.63 0.00


Step 2 UTM z17 Original (EPSG:26917) to Web Merc (EPSG:3857)

cs2cs +init=epsg:26917 +to +init=epsg:3857  -v -E -I
# ---- From Coordinate System ----
+init=epsg:3857
# ---- To Coordinate System ----
+init=epsg:26917
500000.15 4499999.63
500000.15 4499999.63    7357712.08      9347073.72 0.00
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