There are all sorts of assumptions that come together to cause things
to work virtuously (if not correctly) most of the time.
1 - Every shape file in geographic coordinate that I have ever seen
has had its ordinates in lon/lat order.
2 - Geotools will, when parsing a WKT string that does *not* specify
axis order, use lon/lat order, which is virtuous, because it matches
with the reality of (1) above.
3 - The WMS specification prior to 1.3 assumed (and then stated) that
the envelopes provided would be in lon/lat order only.
4 - The WMS specification 1.3 stated that envelopes would be in the
order specified by the CRS.
5 - The EPSG ordering for most geographic coordinate systems is lat/lon.
6 - The epsg-wkt factory uses a properties file of WKT, without
explicit axis order, which means all the geographic coordinate
systems are constructed with lon/lat order (see (2) above).
7 - The epsg-hsql factory uses the EPSG database directly and
constructs CRS with the axis order from EPSG (lat/lon in geographic
cases).
In general, if you ignore axis order *everywhere* things work,
because the raw data tends to be in lon/lat order. It is only when
axis order gets explicit (like in WMS 1.3) that things start to break
down. We "fixed" this problem in the uDig WMS client by simply not
negotiating up to WMS version 1.3.
Not an answer for you, but more grist for the mill...
P
On 19-Feb-06, at 8:11 AM, Simone Giannecchini wrote:
Someone, plsease, correct me if I am wrong here, but I think that
everything works smoothly because basically when features are
involved we ALWAYS make the assumption that we have lon,lat
regardless of the CRS. Is this right or there exists another
explanation?
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