[GRASS-user] Re: import a folder full of shapefiles and reproject on-the-fly?

[Maciej Sieczka]

Tim Michelsen pisze:
> Maciej Sieczka wrote:
>> Moritz Lennert wrote:

>>> So, normally, if you don't give a layer all the shapefiles in the
>>>  directory (dsn=) will be imported.

>> Note this loads the Shapefiles as *layers* (in the GRASS meaning of
>> it) of a single output vector map. Not necessarily what one might
>> want.

> That means that they would get imported as patched tiles?

Not exactly - the geometry would be in a single vector map, but each
ex-tile would have a separate attribute table and categories of features
in each ex-tile would not be unique cross-layer. Read about the layer
concept in the GRASS manual.

> Here is my workflow
> 
> 1) import all landcovers in the UTM location=> v.in.ogr 2) patch all
> landcover tiles => v.patch in=list_of_tiles out=tiles_all 3) import
> the tiles_all into the lat/lon location

That's different than what you wrote initially - you wrote you need to
reproject first, and then import all reprojected tiles into one location.

Given the above workflow, mind that each UTM zone is a different CRS
actually. Do all your shapefiles fit into a single UTM zone?

> Can this be done more efficiently?

You can patch and reproject multiple shapefiles with ogr2ogr alone. See
it's manual. Then import into GRASS location in a single v.in.ogr step.

>>> You will, however, need a loop for the v.proj step...

>> ogr2ogr is more convenient than going through a temporary location 
>> creation, Shapefile import and reprojection with v.proj, IMHO. Much
>> less work.

> If I want to change the projection of the lat/lon location with
> g.setproj do I also need to reporject all layers inside that
> location?

I don't quite understand what you mean.

Maciek

-- 
Maciej Sieczka
www.sieczka.org