[GRASS-user] hint about r.out.xyz

[Markus Neteler]

On Mon, Nov 25, 2013 at 2:25 PM, Vincent Bain <bain at toraval.fr> wrote:
> Hi again dear grass users,
>
> fiddling with point cloud data, I notice a capability of r.out.xyz which
> is neither documented nor allowed from the gui interface, at least in
> GRASS 6.4.
>
> In order to produce an ascii pointcloud file following this pattern :
> x y z r g b
> (i.e. each point of the cloud is described by its coordinates picked
> from an elevation raster and a RGB value picked from an imagery raster)
> I ran several r.out.xyz commands, then joined the result in a single
> file cloud.dat by piping three join commands.
>
> Anyway, later I accidentally typed :
> r.out.xyz fs=" " in=elev,map.red,map.green,map.blue out=cloud.dat
>
> ... and it produced the right pointcloud in one go.

Welcome, you found an undocumented "bug" (here: feature) :-)

> Perhaps it can be useful (tell me if I miss something rhedibitory with
> this usage) :
> - to update the module documentation
> - to allow multiple input selection from the gui interface.

The reason is: r.out.xyz is simply a front-end to "r.stats -1gn" which
accepts multiple input.

The change (if desired) would be as simple as this:

svn diff
Index: r.out.xyz
===================================================================
--- r.out.xyz (revision 58314)
+++ r.out.xyz (working copy)
@@ -24,6 +24,7 @@
 #% gisprompt: old,cell,raster
 #% key_desc: name
 #% description: Name of input raster map
+#% multiple: yes
 #% required: yes
 #%end
 #%option

Then also the GUI supports it automatically...

If there are no objections, I could add this in SVN.
Perhaps you could send me a manual page snipped to be included?

Markus