Re: [Geotools-gt2-users] beginners question

[Frankie B. <fbo...@gm...>]

This is completely of topic, but I want to ask anyway, since I don't know
where else to turn:

What are good books to get started on Cartography and GIS?

(For a complete newbie, that knows about math and computers)

Thank you


On 12/21/05, Rueben Schulz <r_j...@ya...> wrote:
>
> To Frankie,
>
> Hi. You should be able to notice when the projection is changed. If uDig
> does not know the CRS for your data (ie the *.prj file is missing on not
> parsable) then it will not transform the data's coordinates. Attached is
> a *.prj file that should work (assuming I got your shapefile name
> correct). The prj file just has the WKT information on one line.
>
> Your shapefile has latitude and longitude coordinates, which is a
> geographic coordinate reference system. A geographic CRS (aka SRS) just
> records datum information (among a few other things like axis order).
> Your data is using the NAD83 datum. A projected CRS has a geographic CRS
> + a projection and projection parameters.
>
> Also, if your map is shown on its side (90 degree rotation), try
> changing the axis order in the *.prj file. The WKT says it is Lat/Long,
> but shapefile coordinates are usually long/lat.
>
> Since your data covers the entire world, some projections will cause
> problems. For example, the poles cannot be projected with a mercator
> projection (though if the extent info given below is correct, you might
> be able to project everything with a mercator). Also, the transverse
> mercator (used for UTM) is not well defined when you are greater than
> about 30 degrees from a central meridian. I was hoping to address some
> of these issues during the summer, but ran out of time. Also, not too
> many people have needed to play with world maps.
>
> Fortunately, uDig will only project data that is displayed on the map.
> So if you want to try a UTM projection, zoom in to a valid area and then
> change the projection. For example, zoom into the west coast of north
> america and change the map's CRS to NAD83/UTM zone 10N.
>
> I hope you can get this working. I couldn't get the new New Zealand Map
> Grid projection working this morning, but I have not checked if it made
> it into the new uDig release.
>
> Oh, about your ps below. That is weird. According to the WKT the data is
> not projected.
>
> Rueben
>
>
> On Tue, 2005-20-12 at 10:11 +0100, Frankie Bollaert wrote:
> > Hello Rueben,
> >
> > First of all thank you, I had installed uDig some time ago, but I had
> > not noticed this button at the bottom.
> >
> > Using vmap0 data that I had acquired from mapMart I think I was able
> > to change the projection that uDig used.  (I am not totally sure
> > because the map is too small.)
> >
> > But using the shapefiles I made myself from the vmap0 data from NIMA I
> > was not able to change the projection.  Even after I made a .prj file
> > using notepad, using the following data that I got from ogrinfo:
> >
> > Using ogrinfo I got this from the original data:
> > $ /cygdrive/c/gis/FWTools/bin/ogrinfo.exe
> > gltp:/vrf/gis/vmap0/v0eur/vmaplv0/rference 'polbnd@polbnd
> > (*)_area' | less
> > ERROR 4: OGDI Driver doesn't support update.
> > Had to open data source read-only.
> > INFO: Open of `gltp:/vrf/gis/vmap0/v0eur/vmaplv0/rference'
> > using driver `OGDI' successful.
> >
> > Layer name: polbnd@polbnd(*)_area
> > Geometry: Polygon
> > Feature Count: 2136
> > Extent: (- 179.999900, -89.999900) - (179.999900, 83.623596)
> > Layer SRS WKT:
> > GEOGCS["NAD83",
> >     DATUM["North_American_Datum_1983",
> >         SPHEROID["GRS 1980",6378137,298.257222101,
> >             AUTHORITY["EPSG","7019"]],
> >         TOWGS84[0,0,0,0,0,0,0],
> >         AUTHORITY["EPSG","6269"]],
> >     PRIMEM["Greenwich",0,
> >         AUTHORITY["EPSG","8901"]],
> >     UNIT["degree", 0.0174532925199433,
> >         AUTHORITY["EPSG","9108"]],
> >     AXIS["Lat",NORTH],
> >     AXIS["Long",EAST],
> >     AUTHORITY["EPSG","4269"]]
> >
> > I have no clue why this is, aren't the coordinates used in the
> > shapefile simple longitudes and latitudes?  That should mean you
> > should be able to display them in no matter what projection?
> >
> > Have a nice day,
> > Frankie
> >
> >
> > ps.  When I use the vmap0 data from the geotools program, it says it
> > is using a Cartesian projection.
>
>


--
Frankie