Hello,
I'm trying to combine some raster and vector data from www.pasda.psu.edu (links below). The raster (DOQ) and vector (SHAPE) are in different projections. I've created locations for each and imported them. When I re-project with v.proj (or r.proj) the two, which should overlap, are no where near each other.
The region for the raster was set with info from gdalinfo and worked straight away, i.e. I could d.rast and see it. The vector files meta data had bounding coordinates that appear to be in lat/lon and so were useless for its projection (aea). Setting the region from the vector once it was imported seemed to work though.
Now the only problem is that, when combined, the two regions don't overlap.
Are there any good primers on projections and grass regions and importing data? I couldn't find anything useful on the web-site.
Thanks.
Sean
ftp://www.pasda.psu.edu/pub/pasda/compendium/countbnd.zip
ftp://www.pasda.psu.edu/pub/pasda/doq/cherry_grove_pa_ne.zip
R. Sean Fulton said:
Hello,
I'm trying to combine some raster and vector data from
www.pasda.psu.edu (links below). The raster (DOQ) and vector (SHAPE)
are in different projections. I've created locations for each and
imported them. When I re-project with v.proj (or r.proj) the two,
which should overlap, are no where near each other.
The region for the raster was set with info from gdalinfo and worked
straight away, i.e. I could d.rast and see it. The vector files meta
data had bounding coordinates that appear to be in lat/lon and so
were useless for its projection (aea). Setting the region from the
vector once it was imported seemed to work though.
Now the only problem is that, when combined, the two regions don't
overlap.
Are there any good primers on projections and grass regions and
importing data? I couldn't find anything useful on the web-site.
Have you tried the Tutorial at http://grass.itc.it/gdp/grass5tutor/,
especially the chapter called "The GRASS Region" ?
Moritz
On Thu, 15 May 2003, R. Sean Fulton wrote:
Hello,
I'm trying to combine some raster and vector data from
www.pasda.psu.edu (links below). The raster (DOQ) and vector (SHAPE)
are in different projections. I've created locations for each and
imported them. When I re-project with v.proj (or r.proj) the two,
which should overlap, are no where near each other.
Can you provide the output of the g.projinfo command for each location?
This shows the details of the projection parameters and perhaps there
might be something obviously wrong that somebody would be able to spot.
How far away do you mean by no where near each other (I assume not
overlapping at all?)
Other things that might be wrong are wrong units (feet/metres) (which
would give a large error), wrong datum (which would give an error of the
order of 100 metres), wrong false easting/northing offset (another large
error). You may change the parameters by directly editing the PROJ_INFO
and PROJ_UNITS files in the PERMANENT directory for your location.
The region for the raster was set with info from gdalinfo and worked
straight away, i.e. I could d.rast and see it. The vector files meta
data had bounding coordinates that appear to be in lat/lon and so
were useless for its projection (aea). Setting the region from the
You could convert them with m.proj2 from GRASS or (preferably) cs2cs from
the PROJ.4 distribution ( http://remotesensing.org/proj/ ).
Are there any good primers on projections and grass regions and
importing data? I couldn't find anything useful on the web-site.
I could try writing something about how projection is handled in GRASS,
although I don't really do much importing of ready-made datasets (there
aren't that many available for free in Europe) and so am unaware of the
type of problems people may face.
Paul Kelly
At 6:00 PM +0200 2003/05/15, Moritz Lennert wrote:
R. Sean Fulton said:
Hello,
I'm trying to combine some raster and vector data from
www.pasda.psu.edu (links below). The raster (DOQ) and vector (SHAPE)
are in different projections. I've created locations for each and
imported them. When I re-project with v.proj (or r.proj) the two,
which should overlap, are no where near each other.
The region for the raster was set with info from gdalinfo and worked
straight away, i.e. I could d.rast and see it. The vector files meta
data had bounding coordinates that appear to be in lat/lon and so
were useless for its projection (aea). Setting the region from the
vector once it was imported seemed to work though.
Now the only problem is that, when combined, the two regions don't
overlap.
Are there any good primers on projections and grass regions and
importing data? I couldn't find anything useful on the web-site.
Have you tried the Tutorial at http://grass.itc.it/gdp/grass5tutor/,
especially the chapter called "The GRASS Region" ?
Moritz
Thanks, Moritz. I hadn't come across this document before.
Sean
On Thu, May 15, 2003 at 01:45:03PM -0400, R. Sean Fulton wrote:
At 6:00 PM +0200 2003/05/15, Moritz Lennert wrote:
>R. Sean Fulton said:
[...]
>> Are there any good primers on projections and grass regions and
>> importing data? I couldn't find anything useful on the web-site.
>
>Have you tried the Tutorial at http://grass.itc.it/gdp/grass5tutor/,
>especially the chapter called "The GRASS Region" ?
>
>Moritz
Thanks, Moritz. I hadn't come across this document before.
Sean
Should we somehow restructure the web site? Suggestions are
always welcome! I feel that the pages related to the issues
- new user and GRASS usage
- new programmer and GRASS programming
should be improved/added/whatever.
Markus Neteler
Markus Neteler said:
On Thu, May 15, 2003 at 01:45:03PM -0400, R. Sean Fulton wrote:
At 6:00 PM +0200 2003/05/15, Moritz Lennert wrote:
>R. Sean Fulton said:
[...]
>> Are there any good primers on projections and grass regions and
>> importing data? I couldn't find anything useful on the web-site.
>
>Have you tried the Tutorial at http://grass.itc.it/gdp/grass5tutor/,
>especially the chapter called "The GRASS Region" ?
>
>Moritz
Thanks, Moritz. I hadn't come across this document before.
Sean
Should we somehow restructure the web site? Suggestions are
always welcome! I feel that the pages related to the issues
- new user and GRASS usage
- new programmer and GRASS programming
should be improved/added/whatever.
I would actually plead for integrating them into the GDP. People should
see one link on the home page called "Documentation" and within those
documentation pages they should be orientated according to their needs,
i.e. first-time user, general user, programmer, etc... That way we could
reduce the number of links on the home page (for example, do we need a
special link to doc on simulation models on the home page ?).
Does that make any sense ?
Moritz