[postgis-users] Bug or Problem with st_transform
woodbri at swoodbridge.com
Tue May 18 08:39:42 PDT 2010
Mark Cave-Ayland wrote:
> Stephen Woodbridge wrote:
>> Hi guys,
>> This is looking like it might be a bug on version "POSTGIS="1.3.3"
>> GEOS="3.0.0-CAPI-1.4.1" PROJ="Rel. 4.6.0, 21 Dec 2007" USE_STATS"
>> which I know is ancient, but upgrading is not trivial.
>> What I am trying to do is construct a shape in 900913 in meters and
>> then rotate, transform it to 4326 and translate it to a location.
>> The problem is the transform does not look correct. To just rough out
>> the math, 4030 meters should be about 0.036202 degrees based on
>> 4030/40075016*360 = 0.036202 but st_transform is giving back numbers
>> like -5.67596869587729e-09
>> Is this a known problem on this version?
>> Is my logic faulty?
>> Is there a better way to do this?
> Hi Steve,
> The first thing I would suggest is that you run the same query on a
> spare fresh 1.4/1.5 installation and see what happens. The
> transformation code had a good tidy up and some logic corrections within
> that timeframe, including better reporting of error messages.
Hi Mark, et al,
1) Can someone run this query 1.4 and report back the results:
SELECT astext(st_linefromtext('LINESTRING(0 0,4030 0,4030 4030,0 4030)',
astext(st_rotate(st_linefromtext('LINESTRING(0 0,4030 0,4030
4030,0 4030)', 900913), radians(90))),
0,4030 0,4030 4030,0 4030)', 900913), radians(90)), 4326)),
0,4030 0,4030 4030,0 4030)', 900913), radians(90)), 4326),-71.26162,
It assumes that you have 900913 loaded in your spatial_ref_sys table.
2) Does anyone know where I can get postgis 1.4 for debian lenny. I can
get postgresql 8.4 from from backports.org, but they do not have postgis
there. Ideally, at package like postgresql-8.3-postgis based on 1.4
would be simplest, but I'm willing to take a couple of days to dump and
reload all my databases to upgrade to postgresql 8.4 also.
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