v.out.arc

[Raymond Venneker]

> Hello
> 
> I am trying to export Grass vector files (areas) to ARC/INFO. I run v.out.arc in order to create 3 ASCII files: prefix.pol, prefix.lab and prefix.txt
> 
> I followed GRASS manual and I can use prefix.pol and prefix.lab to create, with 
> generate command, a coverage, but I do not know to put prefix.txt (containing 
> categories and attributes information) into the created coverage in ARC/INFO.
> 
> I would appreciate any help, thanks
> 
> 
> -------------------------------------------------
> Juan M. Ruiz

I'm afraid I can't help you with running arc/info commands but a word of
caution with respect to v.out.arc:

1) It is alpha code, meaning the program is not yet fully tested

2) I made the following change in the file write.c


	fprintf (fp, "%12.2lf %12.2lf\n", Xptr[i], Yptr[i]);

	changed to:

	fprintf (fp, "%12.6lf %12.6lf\n", Xptr[i], Yptr[i]);

The reason for this is that we were doing a project in Mauretania
and had to supply the data to an engineering company (arc/info
format). Our data was in latitude/longitude format. In Mauretania 1
degree EW is approx 100km.  The first form (12.2) would give us an
accuracy of approx 1km, while the data was gathered with a GPS (approx
25-50m if I recall correctly).

The results looked good, or did we make the horrible mistake of using
v.out.arc in the wrong projection (lat/lon)?

Raymond