[gdal-dev] Followup to Matching ESRI projection/transformations using GDAL/OSR

[adamgutonski]

Hello,

I recently messaged about matching projection/transformations between GDAL/OSR and ESRI (gdal-dev Digest, Vol 213, Issue 35).

I had two follow-up questions regarding transforming from a geographic CRS to a projected CRS. When transforming from EPSG:6318 to a projected CRS EPSG:32015, the point values I receive are different than in ESRI. My first question is, when I am setting the osr.SetAxisMappingStrategy(osr.OAMS_TRADITIONAL_GIS_ORDER) parameter for EPSG:6318, why would the transformation points be different?

My second question is regarding the compound transformation that ESRI applies. In this example ArcPy uses the "WGS_1984_(ITRF00)_To_NAD_1983_2011 + NAD_1927_To_WGS_1984_3" transformation to project between EPSG:6318 and EPSG:32015. Is there a way to replicate such a transformation using the python GDAL/OSR libraries?

ESRI code:

arc_fromsr = arcpy.

SpatialReference

(6318)

arc_tosr = arcpy.

SpatialReference

(32015)

arcpoint = arcpy.

PointGeometry

(

arcpy.

Point

(

*

test_coords)

, arc_fromsr

)

transformers = arcpy.

ListTransformations

(

arc_fromsr, arc_tosr

)
# transformers[0] is WGS_1984_(ITRF00)_To_NAD_1983_2011 + NAD_1927_To_WGS_1984_3

new_arcpoint = arcpoint.

projectAs

(

arc_tosr, transformers

[0])

GDAL\OSR code:

to_nad = osr.

SpatialReference

()

to_nad.

ImportFromEPSG

(6318)

to_nad.

SetAxisMappingStrategy

(

osr.OAMS_TRADITIONAL_GIS_ORDER

)

final = osr.

SpatialReference

()

final.

ImportFromEPSG

(32015)

outpoint = ogr.

Geometry

(

ogr.wkbPoint

)

outpoint.

AddPoint_2D

(

*

test_coords)

outpoint.

AssignSpatialReference

(

to_nad

)

outpoint.

TransformTo

(

final

)

Input test coordinate: -73.964183, 40.785075

GDAL\OSR transformation output: 602119.3891505665, 286201.7616068426

ESRI\ArcPy transformation output: 602115.6116177095, 286190.512887311

Any help is again, greatly appreciated.

Sincerely,
Adam Gutonski

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