Hi guys,
This is looking like it might be a bug on version "POSTGIS="1.3.3"
GEOS="3.0.0-CAPI-1.4.1" PROJ="Rel. 4.6.0, 21 Dec 2007" USE_STATS" which
I know is ancient, but upgrading is not trivial.
What I am trying to do is construct a shape in 900913 in meters and then
rotate, transform it to 4326 and translate it to a location.
The problem is the transform does not look correct. To just rough out
the math, 4030 meters should be about 0.036202 degrees based on
4030/40075016*360 = 0.036202 but st_transform is giving back numbers
like -5.67596869587729e-09
Is this a known problem on this version?
Is my logic faulty?
Is there a better way to do this?
Thanks,
-Steve
900913 definition:
900913;"spatialreference.org";900913;"PROJCS["unnamed",GEOGCS["unnamed
ellipse",DATUM["unknown",
SPHEROID["unnamed",6378137,0]],PRIMEM["Greenwich",0],
UNIT["degree",0.0174532925199433]],PROJECTION["Mercator_2SP"],
PARAMETER["standard_parallel_1",0],PARAMETER["central_meridian",0],
PARAMETER["false_easting",0],PARAMETER["false_northing",0],
UNIT["Meter",1],
EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0
+lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgri...@null +wktext
+no_defs"]]";"+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0
+x_0=0.0 +y_0=0
+k=1.0 +units=m +nadgri...@null +wktext +no_defs"
Test query showing problem:
SELECT astext(st_linefromtext('LINESTRING(0 0,4030 0,4030 4030,0 4030)',
900913)),
astext(st_rotate(st_linefromtext('LINESTRING(0 0,4030 0,4030
4030,0 4030)', 900913), radians(90))),
astext(st_transform(st_rotate(st_linefromtext('LINESTRING(0
0,4030 0,4030 4030,0 4030)', 900913), radians(90)), 4326)),
astext(st_translate(st_transform(st_rotate(st_linefromtext('LINESTRING(0
0,4030 0,4030 4030,0 4030)', 900913), radians(90)), 4326),-71.26162,
42.30028))
I also get messages:
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
WARNING: transform: -38 (failed to load NAD27-83 correction file)
The results are:
"LINESTRING(0 0,4030 0,4030 4030,0 4030)";
"LINESTRING(0 0,2.46766330028192e-13 4030,-4030 4030,-4030
2.46766330028192e-13)";
"LINESTRING(0 0,3.47552844773335e-25
5.67596699566489e-09,-5.67596869587729e-09
5.67596699566489e-09,-5.67596869587729e-09 0)";
"LINESTRING(-71.26162 42.30028,-71.26162
42.300280005676,-71.261620005676 42.300280005676,-71.261620005676
42.30028)"
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