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<DIV><FONT face=Arial size=2>Hi Everyone</FONT></DIV>
<DIV><FONT face=Arial size=2>Thank you very much for your answer's.
Unfortunately I am very new to all the GIS stuff so I'm flying blind most of the
time. Even the questions you have asked me have actually helped my
understanding.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What I'll d here is explain a little more of what I
am trying to achieve therefore isolating what I'm doing wrong maybe more
apparent. The following is the version() I am using (Windows):-</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>"POSTGIS="1.1.1" GEOS="2.2.1-CAPI-1.0.1" PROJ="Rel.
4.4.9, 29 Oct 2004" USE_STATS"</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>What I have been doing is carrying out the
following SQL INSERT into Postgres. The text Lon/Lat are only there for me while
I'm testing and try to get a better idea of what is happening. The E00....
number is an rfid tag id. The Lat and Long come from a GPS reading using WGS84
datum</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>"INSERT INTO waypoints(rfid,
date,text_lat,text_long,position)VALUES('E004010001CC1B0F',
'04May2006','-45.879185','170.50196',GeometryFromText('POINT(170.50196
-45.879185)', 4326))" </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2> </DIV></FONT>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Next is the record that is created:-</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial
size=2>"8";"E004010001CC1B0F";"2006-05-02";"-45.879185";"170.50196";"0101000020E6100000CEFC6A0E105065401F11532289F046C0"</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The 8 is the SERIAL Primary key.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Now that this is sitting nicely in the Database I
am connecting to it and I want to be able to place the "waypoint" in a map (I'm
playing with a .Net component called mapWindow) in a projection of the
user's choice(ie into the projection of the shapefile). My current level
of understanding is I understand the difference between a datum and
projection but that's about it. I have bought a small book called "Basic GIS
Coordinates" which I'm working through:) </FONT></DIV>
<DIV><FONT face=Arial size=2>I am connecting to the database using NPGSQL data
connector.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have also tried overlaying the above record in
QGIS over a NZ coastline shape file using NZTM and NZMG projections but the
waypoint is several hundred miles to the South of where it should
be.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I suppose Rene is correct in asking what am I
trying to do. I thought that if I had a NZGD 2000 (for example) shape file, to
show the above waypoint on a shape file, I would need to reproject the
waypoint into the NZGD 2000 proection first. I realise this is probably where I
am going wrong.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Mark - I copied the functions from your response
into the arbituary SQL window (eg select
asewkt(transform(geomfromtext('POINT(170.50196<BR>-45.879185)', 4326), 2029));)
and got the same result as in your email ("SRID=2029;POINT(-2815521.73265803
-12147021.3686016)"). This tells me I have things in the correct order now :)
but what is -2815521.73265803 -12147021.3686016 ? Is this the coordinate
projected into x, y coords in NAD27(76) projection? (by the way, I tested all
the functions from your response and they all worked)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Again I apologise for these simplistic questions. I
know once I get my head around projections/datums and the various functions I'll
be fine.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Thank you in advance for any assistance that can be
given.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Cheers</FONT></DIV>
<DIV><FONT face=Arial size=2>Marc</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=rviancos@gmail.com href="mailto:rviancos@gmail.com">René F. Viancos
S.</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=postgis-users@postgis.refractions.net
href="mailto:postgis-users@postgis.refractions.net">PostGIS Users
Discussion</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, May 04, 2006 9:04
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [postgis-users]
Transformation problem using transform()</DIV>
<DIV><BR></DIV>what do you want? make a reproyection or datum shift
?<BR><BR>for datum shift you need to define a custom srid, with a custom
proj4text field parameters.<BR><BR>Regards<BR clear=all><BR>-- <BR>René F.
Viáncos S.<BR>Director de Geomática y TIC <BR>Unidad de Ambiente, Región
Territorio y Espacio, UNARTE<BR>Facultad de Ciencias<BR>Universidad de
Chile<BR>Tel (56-2) 632 62 09<BR>Cel (56 9) 933 72 66<BR><A
href="mailto:rviancos@uchile.cl">rviancos@uchile.cl</A><BR><A
href="mailto:rviancos@gmail.com">rviancos@gmail.com</A>
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