Opened 13 years ago

Closed 13 years ago

#1533 closed defect (fixed)

gdal incorrectly reads projection of ArcView rasters having U.S. survey feet

Reported by: warmerdam Owned by: warmerdam
Priority: normal Milestone: 1.4.1
Component: OGR_SRS Version: 1.4.0
Severity: normal Keywords:
Cc: atomicage@…

Description (last modified by warmerdam)

(Transferred from bugzilla)

ArcView? rasters whose units are U.S. Survey Feet are erroneously reported by GDAL as having international feet.

The procedure used to retrieve the projection is using the Python GDAL bindings as follows:

gd = gdal.Open("c:/rastername/w001001.adf")
gd.GetProjection()

Note that the great majority of State Plane coordinate system use U.S. Survey feet rather than the international foot, and the difference is noticable. The problem appears to arise when GDAL interprets the prj.adf file in the raster.

Following is an example prj.adf for California Zone 6, which uses the U.S. survey foot.

Projection    STATEPLANE
Fipszone      406
Datum         NAD83
Spheroid      GRS80
Units         FEET
Zunits        NO
Xshift        0.0
Yshift        0.0
Parameters    

ArcView? reports the raster having the above prj.adf as being in the the U.S. Survey Foot. It turns out that when Units are called out as FEET in the prj.adf file, this always means U.S. Survey Foot, not the international foot.

When the international foot is the unit, the prj.adf file supplies the number of feet per meter e.g.

Units         3.280839895013123

(That last number equals 1/0.3048 in case I typed it in wrong)

I have done many experiments with ArcView? to check this, creating custom projections, and changing the units between feet and international feet, and ArcView? is consistent. FEET always means the U.S. Survey foot in the prj.adf file.

Change History (3)

comment:2 Changed 13 years ago by warmerdam

Description: modified (diff)

comment:3 Changed 13 years ago by warmerdam

Milestone: 1.4.1
Status: newassigned

Starting work on this. Aiming to resolve it for the 1.4.1 release this week.

comment:4 Changed 13 years ago by warmerdam

Resolution: fixed
Status: assignedclosed

Fixed FEET to be us survey feet in ogr/ogr_srs_esri.cpp.

Also added support for Units values that numeric.

Added tests to autotest/osr/osr_esri.py for both changes.

ogr_srs_esri.cpp changes back ported into 1.4 branch.

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