I am writing a converter to convert from DEM to GRASS raster format.
I use G_open_new_cell_random() to create the new raster file. According to
progman.ps, when I call G_close_cell(), it will write the header file. How
do I set the header info for the cell data so that it will be saved?Should I modify G__.fileinfo[fd]->cellhd to set it?
Or should I call G_put_cellhd() after calling G_close_cell?Modifying the G__ structure seems more logical and efficient, but it is
used in gislib only, so perhaps it shouldn't be accessed directly.The documentation (progman.ps) says that programmers shouldn't need to
use G_put_cellhd. Also, the write routine for cell files
G_put_map_row_random() uses G__.fileinfo[fd]->cellhd to determine what
to write (to see if it's inside the region or not).Eric
eric@detritus.ees.wesleyan.edu
Header information is automatically created for a new raster from the active
region. When you start a program run the active region of the program
is the same as the current region in the file WIND, you can change
the active region using the G_set_region function. It is important
not to change the active region when there are rasters already open.
eg
struct Cell_head new_region;
int fd;
new_region.north=40000;
new_region.south=20000;
new_region.east=20000;
new_region.west=10000;
new_region.ns_res=50;
new_region.ew_res=50;
G_set_region(&new_region);
fd=G_open_cell_new_random("name");
/*do stuff*/
G_close_cell(fd);
the active regino will be forgotten when the prgram ends, and GRASS reverts to
the current region. You shouldn't need to modify the header information directly.
cheers Tom
Tom Charnock O--O
Dept Civil Engineering (~~~~)
Aston University ( __ )
Birmingham B4 7ET UK /|\ /|\
charnotw@sun.aston.ac.uk