[postgis-users] RE: area in meters

[ebcorder at rockwellcollins.com]

If anyone can help on this I don't think this value is correct.  I stored a
polygon away as Lat/Lon with an SRID=4326.  To obtain the area of the
polygon in meters

I wrote this query to transform to UTM.
geom_test=# select area2d(transform((select shapes from poly  where
poly.cell_id=1), 2028));

      area2d
------------------
 30157076.0118284
(1 row)

I don't think this is right.   On  a Delorme map tool I get 443 square
Kilometers.




CREATE TABLE "poly" (
            "cell_id"  int4 NOT NULL
         );


select addgeometrycolumn('poly','shapes',4326,'POLYGON',4);

insert into poly (cell_id,shapes)   values (1,
GeomFromtext('POLYGON((33.745400 -87.095300 1111.000    0,33.727700
-87.099700 1111.000    0,33.718900 -87.102000 1111.000    0,33.708200
-87.093700 1111.000    0,33.699400 -87.095900 1111.000    0,33.688700
-87.087600 1111.000    0,33.678000 -87.079300 1111.000    0,33.665400
-87.060500 1111.000    0,33.663500 -87.049900 1111.000    0,33.652900
-87.041600 1111.000    0,33.649100 -87.020500 1111.000    0,33.647200
-87.010000 1111.000    0,33.643400 -86.988900 1111.000    0,33.641600
-86.978400 1111.000    0,33.637800 -86.957300 1111.000    0,33.635900
-86.946700 1111.000    0,33.640900 -86.923400 1111.000    0,33.639000
-86.912900 1111.000    0,33.635300 -86.891800 1111.000    0,33.633400
-86.881300 1111.000    0,33.620800 -86.862400 1111.000    0,33.617000
-86.841400 1111.000    0,33.615100 -86.830800 1111.000    0,33.611300
-86.809800 1111.000    0,33.607500 -86.788700 1111.000    0,33.605600
-86.778200 1111.000    0,33.601800 -86.757100 1111.000    0,33.606800
-86.733800 1111.000    0,33.604900 -86.723200 1111.000    0,33.611800
-86.710400 1111.000    0,33.618700 -86.697600 1111.000    0,33.625600
-86.684800 1111.000    0,33.632500 -86.672000 1111.000    0,33.641300
-86.669700 1111.000    0,33.658900 -86.665100 1111.000    0,33.667700
-86.662800 1111.000    0,33.678400 -86.671100 1111.000    0,33.689200
-86.679400 1111.000    0,33.699900 -86.687600 1111.000    0,33.701800
-86.698200 1111.000    0,33.705600 -86.719200 1111.000    0,33.718200
-86.738000 1111.000    0,33.720100 -86.748600 1111.000    0,33.715100
-86.772000 1111.000    0,33.718900 -86.793000 1111.000    0,33.720800
-86.803600 1111.000    0,33.724600 -86.824700 1111.000    0,33.719600
-86.848100 1111.000    0,33.721500 -86.858600 1111.000    0,33.725300
-86.879700 1111.000    0,33.727200 -86.890200 1111.000    0,33.731000
-86.911300 1111.000    0,33.732900 -86.921900 1111.000    0,33.745500
-86.940700 1111.000    0,33.747400 -86.951300 1111.000    0,33.751100
-86.972400 1111.000    0,33.754900 -86.993500 1111.000    0,33.765600
-87.001800 1111.000    0,33.769400 -87.022900 1111.000    0,33.762400
-87.035700 1111.000    0,33.764300 -87.046300 1111.000    0,33.757400
-87.059100 1111.000    0,33.759200 -87.069700 1111.000    0,33.752300
-87.082500 1111.000    0,33.745400 -87.095300 1111.000    0))',4326));



Elwood Cordery
Rockwell Collins
Contract Software Engineer
319-295-8248