Opened 13 years ago

Closed 13 years ago

Last modified 13 years ago

#3787 closed defect (fixed)

Wrong inverse flattening in the dictionary of ErMapper spherical datums

Reported by: dron Owned by: warmerdam
Priority: normal Milestone:
Component: OGR_SRS Version: 1.7.0
Severity: normal Keywords:
Cc:

Description

List of ErMapper spherical datums (from the ecw_cs.wkt) contain inverse flattening parameter which looks to be wrong to me. It should be 0 for sphere, not 1 as it is now. There is a patch fixing that:

--- ecw_cs.wkt	(revision 20877)
+++ ecw_cs.wkt	(working copy)
@@ -1368,8 +1368,8 @@
 SAD69,GEOGCS["SOUTH AMERICAN 1969",DATUM["SAD69",SPHEROID["INT67",6378160,298.25]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 SECLV,GEOGCS["QASCO",DATUM["SECLV",SPHEROID["ANS",6378160,298.25]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 SLOVENIA,GEOGCS["SLOVENIAN DATUM",DATUM["SLOVENIA",SPHEROID["BESS1841",6377397.155,299.1528128]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
-SPHERE,GEOGCS["NOT SPECIFIED",DATUM["SPHERE",SPHEROID["SPHERE",6371000,1]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
-SPHERE2,GEOGCS["NOT SPECIFIED",DATUM["SPHERE2",SPHEROID["SPHERE",6370997,1]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
+SPHERE,GEOGCS["NOT SPECIFIED",DATUM["SPHERE",SPHEROID["SPHERE",6371000,0]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
+SPHERE2,GEOGCS["NOT SPECIFIED",DATUM["SPHERE2",SPHEROID["SPHERE",6370997,0]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 SUDAN,GEOGCS["SUDAN DATUM",DATUM["SUDAN",SPHEROID["CLA80IGN",6378249.2,293.4660213]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 TANANAR,GEOGCS["TANANARIVE 1925",DATUM["TANANAR",SPHEROID["INT24",6378388,297]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 TANANPAR,GEOGCS["TANANARIVE 1925",DATUM["TANANPAR",SPHEROID["INT24",6378388,297]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
@@ -1401,7 +1401,7 @@
 USKRAS40,GEOGCS["NOT SPECIFIED",DATUM["USKRAS40",SPHEROID["KRAS1940",6378245,298.3]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 USNWL10D,GEOGCS["NOT SPECIFIED",DATUM["USNWL10D",SPHEROID["NWL10D",6378135,298.26]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 USNWL9D,GEOGCS["NOT SPECIFIED",DATUM["USNWL9D",SPHEROID["NWL9D",6378145,298.25]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
-USSPHERE,GEOGCS["NOT SPECIFIED",DATUM["USSPHERE",SPHEROID["SPHERE",6371000,1]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
+USSPHERE,GEOGCS["NOT SPECIFIED",DATUM["USSPHERE",SPHEROID["SPHERE",6371000,0]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 WGS72BE,GEOGCS["BROADCAST EPHEMERIS",DATUM["WGS72BE",SPHEROID["NWL10D",6378135,298.26]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 WGS72DOD,GEOGCS["WGS 72 (DoD)",DATUM["WGS72DOD",SPHEROID["NWL10D",6378135,298.26]],PRIMEM["Greenwich",0],UNIT["degree",0.0174532925199433]]
 WGS84,GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],TOWGS84[0,0,0,0,0,0,0],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9108"]],AXIS["Lat",NORTH],AXIS["Long",EAST],AUTHORITY["EPSG","4326"]]

I don't know how this file was created, it is possible that generator script should be fixed first and the whole dictionary is regenerated.

Best regards, Andrey

Change History (2)

comment:1 by dron, 13 years ago

Resolution: fixed
Status: newclosed

This is fixed with r20890 in trunk and with r20891 in 1.7 branch. For trunk I have added a test case to catch this problem, see r20892.

comment:2 by warmerdam, 13 years ago

For reference I believe the file is created with gdal/frmts/ecw/lookup.py which puts the inverse flattening in directly from the ermapper source file. I'm not sure it is worth correcting since I am doubtful new versions of the source file are, or will be available.

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