[GRASS-user] How to create an hull / area with v.in.ascii

[Martin Landa]

Hi,

[snip]

2008/2/8, Philipp Steigenberger <userlist at online.de>:
>  Is it is important to have leading blanks in front of the points? Or is it
> just for clarity?

no, they are not important.

>  B 5 1
>  593757.983193 4917668.319328
>  593757.983193 4917668.319328
>  603618.655462 4915223.193277
>  606344.369748 4923801.176471
>  595521.680672 4925244.201681
>  2 3
>
>
>  For my own clarity
>
> B for Boundary, L for Lin,e A for Area, C for Centroid, and P for Point

do not use 'A' since it is superseded type (it has been kept only for
backward compatibility from grass 5)

For defining area use sets of boundaries and centroid.

> 5 is the number of points

yes

> 1 ??? Neteler & Mitasova describe "1 for a single category" - what does this
> mean?

number of categories

> 2 is the layer number
> 3 is the category ID

yes

so e.g. to define two categories for boundary in different layers

B 5 2
 593757.983193 4917668.319328
 593757.983193 4917668.319328
 603618.655462 4915223.193277
 606344.369748 4923801.176471
 595521.680672 4925244.201681
 1 2
 2 3

> In your example the first and second boundary have the same cat ID. Why?

it was just example... no strong reason for that.

Martin

-- 
Martin Landa <landa.martin at gmail.com> * http://gama.fsv.cvut.cz/~landa *