[GRASSLIST:5702] Re: Unrectified DXF importation

[Markus Neteler]

On Fri, Feb 28, 2003 at 03:42:09PM +0800, Dr. Mohamad Firuz Ramli wrote:
> Dear list
> 
> Thanks  to Sandro for helping me in my first problems
> with dxf data.
> 
> I have another problems.
> 
> I try to import unrectified dxf layer. I manage to do it.
> However when I did the transformation using v. transform,
> it shows the transformation process with the residual value.
> But when I tried to display the rectified dxf. It did not show anything.
> 
> I followed the procedure in Neteler and Mitasova's book but I encounter
> a problem such as above.
> 
> This is the procedure that I did.
> 
> v.in.dxf -a dxf=vmap.dxf prefix=vmap      --to import dxf data into ascii
> 
> I want to import road layer inside vmap 
> 
>  v.in.ascii in=vmap.road out=vmap_roadxy
> v.support vmap_roadxy
> g.region -p vect=vmap_roadxy
> d.erase
> d.vect vmap_roadxy
> 
> 
> I managed to display the vmap_roadxy layer on the screen and identify four gcpoints
> in x and y coordinates and its location on the map for the real coordinates and
> save in in ASCII table point as roadgcp

Hi,
Up to now the map name is "vmap_roadxy", right?

> After that
> 
> v.transform in=vmap_road out=vmap_roadtrans point=roadgcp    (as in Neteler and Mitasova book)
> 
> ERROR:Could not find input vector vmap_road

Yes, because the name was wrong.
v.transform reads binary vectors only:
"   v.transform - Transforms an binary vector map layer from one
   coordinate system into another coordinate system."

i.e. the result of v.in.ascii.

> After that I change the input to the one that I convert to binary file
> 
> v.transform in=vmap_roadxy out=vmap_roadtrans point=roadgcp   

Looks better...
 
> The map is transformed with the residual value
> Transformation is complete
> 
> v.support vmap_roadtrans

Here it may help to use
v.support -r vmap_roadtrans

[should we make "-r" a default?]

> g.region -p vect=vmap_roadtrans

Now hopefully shows the correct boundary coordinates.

Markus Neteler