zze-M2S FRISON V ext RD-BIZZ-SOP a écrit :
> INFO [main] (_TestFeatureTransforming.java:28_): Original WGS84 coordinates:
> (7.0, 43.0, NaN)
> INFO [main] (_TestFeatureTransforming.java:33_): (999870.608360379,
> 1789915.8576742434, NaN) <-- GeoTools transform
> INFO [main] (_TestFeatureTransforming.java:37_):
> (980808.5279030021,1788755.1365062557, NaN) <-- SIGForum.org transform
Just tried with Geotools 2.4-SNAPSHOT and got:
980808.527, 1788755.14 <-- GeoTools transform
Which is one centimeter close to sigforum.org calculation.
> CoordinateReferenceSystem crsWGS84 = CRS.decode("EPSG:4326");
> CoordinateReferenceSystem crsLambert2e = CRS.decode("EPSG:27572");
Try CRS.decode("EPSG:4326", true). Same for EPSG:27572.
> Coordinate c1 = *new* Coordinate(7.0, 43.0);
If you only want to transform 2D points, it would be better to use
org.geotools.geometry.DirectPosition2D (or
org.geotools.geometry.GeneralDirectPosition for n-D).
> BTW I have this interesting error message at the begining of the output:
>
> 18 avr. 2007 14:38:27 FactoryRegistry scanForPlugins
>
> ATTENTION: Échec lors de l'initialisation d'un service de catégorie
> "MathTransformProvider". La cause est "NoClassDefFoundError:
> javax/media/jai/WarpAffine".
>
> Could it explain the imprecision?
No. It is more likely that something was wrong with the CRS you built. As a
general rule in case of doubt, alway use System.out.println(crsLambert2e) and
read very carefully what you get (every lines). From your previous email:
AXIS["Lon", EAST],
AXIS["Lat", NORTH],
which is okay, and:
UNIT["grade", 0.015707963267948967],
So this CRS expect (longitude,latitude) in grade units, not degrees. This is not
a mistake; EPSG really defines the "27572" CRS that way and by default Geotools
tries to do exactly what EPSG said.
The "true" argument in CRS.decode(...) above forces the axis order to
(longitude,latitude) even if the EPSG database said the opposite. But in
addition, it also forces angular units to "degrees" even if the EPSG database
said something else.
Martin
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