[GRASS-user] problem in v.drape command

[Hamish]

Dylan Beaudette wrote:
> 
> The v.drape module was created by suggestion of Radim, and implemented
> by an  amateur (me). This bug is one of the last remaining issues in
> the code.  Although it is mentioned in the manual page, it would be
> good to do a simple  test of 
> 
> if vector %in% current region or vector %in% raster bbox
> then run else error and exit
> 
> I am not sure how to implement this check, but if I get some feedback
> I will  submit a patch!


I think the libgis error is appropriate, but that v.drape should not be
trying to load a raster array i,j which is out of range. Perhaps in
these cases the Z value should be set to NULL (nan), or if that is
illegal either set to 0 (with warning) or G_fatal_error() out.

You can check in map is contained within the current region by reading
the map header info and the current region settings,

e.g. read current region into "window":

struct Cell_head window;
G_get_window(&window);

then you have doubles: window.north, .south, .east, .west, .top, .bottom



To read vector bounds:

struct Map_info Map;
BOUND_BOX box;

Vect_open_old_head (&Map, input->answer, mapset);
Vect_get_map_box (&Map, &box);

then you have doubles: box.N, box.S, box.E, box.W, box.T, box.B



compare:

if ( (box.N > window.north) || (box.S < window.south) ||
     (box.E > window.east) || (box.W < window.west) )
    G_warning("Vector exists outside of raster region");

...


Hamish