[Gvsig_english] Creating new layer--specific lines

[Simon Cropper]

On 21/04/11 06:53, triestem wrote:
> I'm trying to create a new layer--I have two point locations, and I need
> them to be connected by a line that is exactly 180 degrees--but only so that
> I can then create lines going through those points at exactly 90 degrees
> from the first line.  Does that make sense?  I need one line through each
> point, each line perfectly perpendicular to the axis that's created by
> connecting the two points.  I've been eyeballing this with the draw tools,
> but haven't been able to figure out how to make it more accurate, but I
> figure there must be a way.
>
> I have looked through the manual, and attempted to follow the instructions
> for entering commands, but nothing good came out of it.  If anyone could
> offer any tips or tricks, I'd really appreciate it.

Hi,

What are you trying to do? Sounds like you are either trying to use a 
GIS software as a CAD program.

Putting aside this ambiguity you could try a few simple tricks I have 
used to make specific grids.

The first is to create a grid using the tools in Sextante. Define one 
point as the origin and the distance between the points as the 
increment. You can then delete those lines you don't want.

Alternatively create a line shapefile and use the command box to specify 
the angle and distance of lines added. See example here...

http://www.gvsig.org/web/projects/gvsig-desktop/docs/user/gvsig-desktop-1-10-manual-de-usuario/gvsig-desktop-1-10-user-manual/gvsig_freemind_toc_view?doc=gvSIG%201.10%20User%20manual/Editing%20tools/Graphic%20editing/Drawing%20commands%20%28points,%20lines...%29/Line

Again, another alternative is to create a GML file with the exact 
specifications for your file. This will allow you to specify the exact 
origin and destination of each line. GML is a simple XML document. To 
see the correct format make a 'rough copy' of what you want as a 
shapefile then export it to the GML format, open it in an editor and 
make what changes you want. You can then just open this again in gvSIG 
and copy to whatever format you want.

In future, when asking for help specify what you are trying to do - that 
is what is the end game. I need a grid, I need to make a square, etc. 
Sometimes it makes it easier to propose solutions. Also note what 
version of gvSIG you are using and what operating system you are on. How 
you work in Windows is different to how you work in Linux.

I hope this has given you some ideas.

-- 
Cheers Simon

    Simon Cropper
    Principal Consultant
    Botanicus Australia Pty Ltd
    PO Box 160, Sunshine, VIC
    W: www.botanicusaustralia.com.au