[GRASS-user] Problem with v.out.ogr?

[Moritz Lennert]

On 28/04/12 10:35, Micha Silver wrote:
>
>
> On 28/04/2012 00:54, Asher Hoskins wrote:
>
>> Hello.
>>
>> I've got a map with multiple layers that was originally created from a
>> DXF file (via v.in.dxf). I want to output a single layer as a KML file
>> so that it can be loaded into Google Earth (for a non-Grass user) but
>> when I do:
>>
>>   v.out.ogr type=line input=esw_g26a format=KML dsn=main.kml layer=7
>>
>> I get all layers output, not just layer 7.
>>
>> Am I doing something silly here?
>
>
> Not silly, but maybe not what you expect.
>
> Layers are database links, so you could very well have a vector with 7
> layers, where all the geographic features, are in all the layers.
> Choosing a certain layer mean choosing which attribute table is
> connected to the features, but not necessarily which features.

That is not completely true: layers are not connections to attribute 
tables, but a means of allowing different (thematic) identifications of 
the same features in a vector map. You can optionally link each layer to 
an attribute table. Whether a feature exists in a layer or not is 
determined by whether that feature has a category value in that layer.

See the recently revised vector intro in the docs for more info [1].

When you display the map, chosing to display only layer 7, what do you 
see ? And what does v.category option=report give you ?

Moritz

[1] http://grass.fbk.eu/grass64/manuals/html64_user/vectorintro.html