Re: [Geotools-devel] Explanation of Bursa Wolf Parameters

[Paul R. <pr...@re...>]

OK, we need to go through our properties file and make sure we use=20
consistent datum names

Martin Desruisseaux wrote:

> Jesse Eichar a =E9crit :
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>> I'm doing some reprojection but I keep getting the error:
>>
>> org.opengis.referencing.operation.OperationNotFoundException: Bursa=20
>> wolf parameters required.
>=20
>=20
>=20
> Bursa-Wolf parameters is the TOWGS84[...] clause.
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> If there is no datum change (i.e. the ellipsoid are the same in source=20
> and target CRS), then there is no need for Bursa-Wolf and you should no=
t=20
> get this exception.
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> In the example you provided, there is (almost!) a datum change. The=20
> source CRS use the following:
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> DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137,298.257222101=
]]
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> while the target CRS use the following:
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> DATUM["North_American_Datum_1983",SPHEROID["GRS_1980",6378137,298.25722=
2101]]=20
>=20
>=20
> I agree, this is actually the same datum. But CRS don't know that,=20
> because there is a "D_" in the source CRS that is not present in target=
=20
> CRS (there is not really a reliable way to know if 2 datum are differen=
t=20
> except than using their name; the SPHEROID clause alone is not enough).=
=20
> The CRS think "I need to performs a datum shift from "D_North..." to=20
> "North...", but I don't know how to do that since the user didn't=20
> provides any TOWGS84[...] clause" (with non-zeros values, of course).
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> A quick fix is to just remove the "D_" in the source datum name.
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> A more long-term fix is to provides some kind of "Datum names" database=
.=20
> We should open a JIRA task if there is a strong demand for it.
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>     Martin.
>=20
>=20
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