## geotools-gt2-users

 Re: [Geotools-gt2-users] Rv: Problem with coordinate tranformation in coordinates relations From: Martin Desruisseaux - 2006-09-06 11:03:52 ```(Note: please keep emails on the public mailing list instead of private e= mails) mariano s kohan s a =E9crit : > the coordinates that i have to process applied only inside the area of = a=20 > country. Can i define a proyection a little more accurate in a specific= =20 > area (for example 20=BA S to 50=BA S lat and 55=BA W to 72 =BA W)? how= ? You may try a Lambert conical with two secant latitudes, one around 30=B0= S and one around 40=B0S. Try=20 the following from the command line: java -classpath gt2-referencing-2.3-SNAPSHOT.jar=20 org.geotools.referencing.operation.DefaultMathTransformFactory Lambert_Co= nformal_Conic_2SP It should list you the parameter accepted by this map projection. Two par= ameters of interest are=20 "standard_parallel_1" and "standard_parallel_2". > is there some way to calculate the angle defined by the path of the=20 > orthodomic distance with this accurated mode? Try org.geotools.referencing.GeodeticCalculator (look at 'getAzimuth' met= hods). Martin. ```
 Re: [Geotools-gt2-users] Rv: Problem with coordinate tranformation in coordinates relations From: mariano s kohan s - 2006-09-10 20:19:14 Attachments: Message as HTML ```thanks Martin ! i make some test with points at far distance inside the data to process and the difference in distance was about only 1 km. But i have some difference with the angles about the way of measurement that i want to confirm. Using GeodeticCalculator the method getAzimuth return the angle maked with respect the north axis in clockwise sense (and betwen 180 to -180 degrees). Using LineSegment over the proyected points the angle returned it has to be the one maked with respect the horizontal x-axis (positive) in counterclockwise sense. But i saw that the x-axis give and angle of 36.6º aproximated. To correct this deviation i set the parameter central_meridian to the mid point betwen the max and min longitudes values (for example -63.5º for longitude from 55ºW to 72ºW). It's ok setting this value? it has the correct value? (where i can find more information to undestand a little more the proyections settings?) this is the wkt from the proyected crs: PROJCS["WGS 84 / Lambert_Conformal_Conic_2SP", GEOGCS["WGS84", DATUM["WGS84", SPHEROID["WGS84", 6378137.0, 298.257223563]], PRIMEM["Greenwich", 0.0], UNIT["degree", 0.017453292519943295], AXIS["Geodetic longitude", EAST], AXIS["Geodetic latitude", NORTH]], PROJECTION["Lambert_Conformal_Conic_2SP"], PARAMETER["central_meridian", -63.5], PARAMETER["latitude_of_origin", 0.0], PARAMETER["standard_parallel_1", -30.0], PARAMETER["false_easting", 0.0], PARAMETER["false_northing", 0.0], PARAMETER["standard_parallel_2", -40.0], UNIT["m", 1.0], AXIS["x", EAST], AXIS["y", NORTH]] thanks, Mariano Martin Desruisseaux escribió: You may try a Lambert conical with two secant latitudes, one around 30°S and one around 40°S. Try the following from the command line: java -classpath gt2-referencing-2.3-SNAPSHOT.jar org.geotools.referencing.operation.DefaultMathTransformFactory Lambert_Conformal_Conic_2SP It should list you the parameter accepted by this map projection. Two parameters of interest are "standard_parallel_1" and "standard_parallel_2". Try org.geotools.referencing.GeodeticCalculator (look at 'getAzimuth' methods). Martin. --------------------------------- Preguntá. Respondé. Descubrí. Todo lo que querías saber, y lo que ni imaginabas, está en Yahoo! Respuestas (Beta). Probalo ya! ```
 Re: [Geotools-gt2-users] Rv: Problem with coordinate tranformation in coordinates relations From: Martin Desruisseaux - 2006-09-21 19:04:37 ```mariano s kohan s a écrit : > [...snip...]. To correct this deviation i set the parameter > central_meridian to the mid point betwen the max and min longitudes > values (for example -63.5º for longitude from 55ºW to 72ºW). It's ok > setting this value? it has the correct value? In the case of "Lambert_Conformal_Conic_2SP", I do not expect the central meridian to have much effect on map projection deformations. It should not hurt however, so the above setting is probably okay. The "standard_parallel_1" and "standard_parallel_2" parameters are likely to have more impact. You may consider to set them closer to the area of interest. Martin. ```

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