[GRASSLIST:193] Re: Question about re-projecting points imported from Postgres

[David Finlayson]

If I understand you correctly, you have a table in Postgres that
happens to contain x, y coordinates in addition to other attributes
but is not a PostGIS layer. You were able to convert the X,Y points
into a GRASS vector file (points) using v.in.db AND this new vector
file seems to work in the lat long Location.

Now when you try to project the new vector file into a LCC location it
fails. What is the error you are getting? That seems like it should
work.

As a test, have you tried exporting the postgres table as a csv file
(at least pointid, x and y) and then load the vector with v.in.ascii?
You will be able to link the ID, X,Y CSV file back to the original
postgres attribute table using the ID column. Does this simple vector
file project?

David

On 3/16/06, Thomas Adams <Thomas.Adams at noaa.gov> wrote:
> David,
>
> Maybe you don't understand. The Postgres table is for points and has the
> lat-long location; using v.in.db one is required to identify the x,y
> location. The additional attributes are read as well, of course. I can
> successfully import the Postgres table into GRASS into my lat-long
> location. If I then try to re-project the points into a LCC projection
> (from the LCC location), the v.proj does not seem to work. Is this what
> you previously understood I was tying to do or do now?
>
> Who would know whether or not this can be done?
>
> Thanks for you r responses…
>
> Tom
>
> David Finlayson wrote:
> > Ah, I understand now. I'm afraid I can't help you with this. I've only
> > used databases to hold attribute information not the topology also. I
> > haven't tried PostGIS yet.
> >
> > David
> >
> > On 3/15/06, Thomas Adams <Thomas.Adams at noaa.gov> wrote:
> >
> >> List:
> >>
> >> I have a Lat-Long location into which I have successfully imported
> >> points from Postgres (a further question about this further below). What
> >> I want to do is to re-project the points into a Lambert Conic Conformal
> >> location using v.proj. When I try to do this, it does not work — it
> >> seems as though GRASS does not know how to do this. I have been able to
> >> do this successfully with points imported using v.in.ascii. It seems I
> >> am missing something, either conceptually or procedurally…
> >>
> >> The further question about using v.in.db, the 'key' parameter in the
> >> documentation claims this is a string, which makes since to me, but when
> >> v.in.db is run, GRASS complains that an integer is needed. I'm guessing
> >> the integer that's supplied is the column/field number (beginning with
> >> '1'); if true, this seems to be inconsistent by what the 'x', 'y', and
> >> 'z' fields require — just a thought.
> >>
> >> Tom
> >>
> >> --
> >> Thomas E Adams
> >> National Weather Service
> >> Ohio River Forecast Center
> >> 1901 South State Route 134
> >> Wilmington, OH 45177
> >>
> >> EMAIL:  thomas.adams at noaa.gov
> >>
> >> VOICE:  937-383-0528
> >> FAX:    937-383-0033
> >>
> >>
> >>
> >
> >
> > --
> > David Finlayson
> >
>
>
> --
> Thomas E Adams
> National Weather Service
> Ohio River Forecast Center
> 1901 South State Route 134
> Wilmington, OH 45177
>
> EMAIL:  thomas.adams at noaa.gov
>
> VOICE:  937-383-0528
> FAX:    937-383-0033
>
>


--
David Finlayson