[GRASSLIST:3997] Re: ps.map grid in Lat/Lon

[Hamish]

> > i'm want to  overlay a map of a Lat/Lon location with a grid that
> > has less than 1 degree spacing.
> > is that possible? (geogrid is not available for lat/lon and if i use
> > 
> > grid nothing happens when i choose a spacing less than 1)
> >
> I had a similar problem back with GRASS 5.0.0.  I was told at the time
> 
> that ps.map did not support floating point grids, hence the problem 
> with lat-long locations.  I don't know if it has been fixed, but a 
> simple workaround is to make a vector grid with v.mkgrid and just 
> display that along with whatever else you want with ps.map.  Thanks to
> 
> whomever suggested that to me.


The attached patch adds this to ps.map in GRASS 5.7.

Before trying that though you might try the "geogrid" command [5.7
only], which will draw a lat/lon grid over a non-Lat/Lon location map.

I haven't put this in CVS as it needs some checking over to make sure it
doesn't cause other problems (eg it tests grid==0 when 0 is now floating
point). Maybe someone with a keener eye for C than me can comment.
It might be better to just work on getting geogrid to do lat/lon?


Results on the map look great, formats text into deg:minutes, but you
may need to use a lot of precision to get 5-minute ticks to round
correctly. e.g., for 5' use something like "grid 0.08333333333333"

This makes the mapinfo command look pretty wonky for anything smaller
than 0.25 of a degree though. I guess G_format_easting() could fix that?


e.g., for the global lat/lon dataset:  [zoom in]

ps.map out=test.ps << EOF
raster nations
grid 0.25
  numbers 1
  end
mapinfo
  where 0.5 8.5
  end
end
EOF
gv test.ps



Hamish
-------------- next part --------------
Index: main.c
===================================================================
RCS file: /home/grass/grassrepository/grass51/ps/ps.map/main.c,v
retrieving revision 1.6
diff -u -r1.6 main.c
--- main.c	27 Jan 2004 12:59:16 -0000	1.6
+++ main.c	22 Jul 2004 23:21:38 -0000
@@ -625,7 +625,7 @@
 	{
 	    PS.grid = -1;
 	    PS.grid_numbers = 0;
-	    sscanf(data, "%d", &PS.grid);
+	    sscanf(data, "%lf", &PS.grid);
 	    if (PS.grid < 0)
 	    {
 		PS.grid = 0;
Index: ps_info.h
===================================================================
RCS file: /home/grass/grassrepository/grass51/ps/ps.map/ps_info.h,v
retrieving revision 1.3
diff -u -r1.3 ps_info.h
--- ps_info.h	27 Jan 2004 12:59:16 -0000	1.3
+++ ps_info.h	22 Jul 2004 23:21:38 -0000
@@ -41,12 +41,12 @@
     int do_colortable;
     int do_scalebar;
     int num_psfiles;
-    int grid, grid_color, grid_numbers, grid_numbers_color, grid_fontsize;
+    int grid_color, grid_numbers, grid_numbers_color, grid_fontsize;
     float grid_cross;
+    double grid, grid_width, geogrid_width;
     char geogridunit[64];
     int geogrid, geogrid_color, geogrid_numbers;
     int  geogrid_numbers_color, geogrid_fontsize;
-    double grid_width, geogrid_width;
     int do_outline, outline_color;
     int cell_fd;
     int row_delta, col_delta; 
Index: do_grid.c
===================================================================
RCS file: /home/grass/grassrepository/grass51/ps/ps.map/do_grid.c,v
retrieving revision 1.2
diff -u -r1.2 do_grid.c
--- do_grid.c	10 Jul 2003 17:59:32 -0000	1.2
+++ do_grid.c	22 Jul 2004 23:21:39 -0000
@@ -109,7 +109,8 @@
 {
     double g;
     char num_text[50];
-    int grid, vy, vx, hy=0, hx=0;
+    double grid;
+    int vy, vx, hy=0, hx=0;
     int first, len, x, y, last_bottom, last_right;
     int rounded_grid, margin;
 
@@ -120,7 +121,7 @@
     rounded_grid = 1;
     if (PS.w.proj != PROJECTION_LL)
     {
-	sprintf(num_text, "%d", PS.grid);
+	sprintf(num_text, "%lf", PS.grid);
 	len = strlen(num_text);
 	while (len-- && num_text[len] == '0') rounded_grid *= 10;
 	if (rounded_grid == 10) rounded_grid = 1;
Index: map_info.c
===================================================================
RCS file: /home/grass/grassrepository/grass51/ps/ps.map/map_info.c,v
retrieving revision 1.1
diff -u -r1.1 map_info.c
--- map_info.c	26 Mar 2003 15:56:15 -0000	1.1
+++ map_info.c	22 Jul 2004 23:21:39 -0000
@@ -47,7 +47,7 @@
     	{
 	    k = 5.5;
             sprintf(buf, 
-	        "%d %s", PS.grid, G_database_unit_name(PS.grid != 1));
+	        "%g %s", PS.grid, G_database_unit_name(PS.grid != 1));
     	    fprintf(PS.fp, "(%s) SW pop /t2 XD\n", buf);
 	    fprintf(PS.fp, "t1 t2 lt {/t1 t2 def} if \n");
     	}
@@ -74,7 +74,7 @@
     if (PS.grid)
     {
         sprintf(buf, 
-	    "%d %s", PS.grid, G_database_unit_name(PS.grid != 1));
+	    "%g %s", PS.grid, G_database_unit_name(PS.grid != 1));
         show_text(x, y - dy, "GRID:");
         fprintf(PS.fp, "(%s) sx %.1f MS\n", buf, y - dy);
         y -= dy;