[postgis-devel] Help with GPS Coord in PostGIS
chodgson at refractions.net
Thu May 11 12:18:41 PDT 2006
This would probably get more replies on the user list, but... I have a
few suggestions for you.
1) check your spatial_ref_sys table, the srid you are using should be in
that table corresponding to the correct srtext and proj4text values. If
your spatial_ref_sys table is empty, then load the spatial_ref_sys.sql
file that came with postgis.
2) put a projection definition in your mapfile which corresponds to your
3) your query for inserting the geometries is missing "setsrid()" but
supplies the srid ... I'm guessing that's a cut/paste typo in the
e-mail, because otherwise your query would probably fail
4) I don't know what makeline does, but it looks like a compound
function that puts points together into a line? I don't know how that
could work since they would need to be ordered somehow... plus you don't
have a "group by" clause so there is nothing to be compounded, unless I
guess your are putting the entire table together... basically, if the
query inside the paretheses doesn't work in your psql, it's not going to
work for mapserver either...ie. does this query succeed?
select makeline(the_geom),1 as gid from gps_coord
Even if it does, work, you might need to rename the geom column to
something else like:
DATA new_geom from (select makeline(the_geom) as new_geom, 1 as gid from
gps_coord) USING ...
5) If what you want is to just show the whole path then maybe you should
just load a single linestring geometry instead of a bunch of points? SO
use perl or whatever scripting language you like to parse your input
file into one big insert statement for just a single row with a single
linestring geometry. Or, if your path is quite long, then insert a bunch
of linesegments, each N points long. I suppose you could do the same in
sql instead of perl if you prefer, the general idea is just to make the
linestring(s) first so that they are easier/faster/simpler to display
So, I hope something in there helps. If not, try on the users list.
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