An efficient tool to rasterize shapefile polygons as "polygon area on grid cells"
There are two Fortran main programs in current repository:
- shp2grid.f90: the key program, to rasterize shapefiles
- test_read_shapefile.f90: a simple script to test the shapefile reading functions
The main programs use the following modules:
- shapefile_io_module.f90: central module, to read shapefile data (*.shp and *.shx files)
- netcdf_output.f90: contains subroutine to generate and write netCDF outputs
- scan_arguments.f90: subroutine for analyzing command-line arguments passed to the main program
- geography.f90: geographic tools: Earth model, radius, and authalic latitude
- miscellaneous_functions.f90: various tools: modify file names, time string, etc.
- backups/: backup of old or incomplete code
- data_example/: shapefiles for testing
The main program (shp2grid) needs the netcdf-fortran library (https://docs.unidata.ucar.edu/netcdf-fortran/current/index.html).
On Linux operating systems: apt install libnetcdff.
Because I couldn't find a Fortran shapefile library, I wrote my own module to read shapefile data from binary files *.shx and *.shp (with Fortan option "form='unformatted'"): shapefile_io_module.f90
Before compiling, make sure that the netCDF-Fortran library is installed and configured for your Fortran compiler.
Then, update the environement variables export FC=_your_fortran_compiler_ and export NCPATH=_current_netcdf_path_.
Tip: use nc-config to determine those elements.
Alternatively, open the Makefile with any text editor and directly edit the Makefile variables "FC", "NCPATH",
"inc_flags", "lib_flags" or "NETCDF_FLAGS".
Compile the executable with make (shortcut for make shp2grid), or make test_read_shapefile.
Note that this second program does not need the netCDF library.
To compile with debugging options, do make clc and make shp2grid MODE=debug.
...
...
...
A Comprehensive "help" text is written in 'help_message.txt' (and displayed when typing ./shp2grid --help)
Shapefiles example in subrepertory data_example/ are taken from database:
Global Self-consistent Hierarchical High-resolution Geography, GSHHG
Version 2.3.7 June 15, 2017
Distributed under the Lesser GNU Public License
Credit: Paul Wessel (primary contact: pwessel@hawaii.edu), Walter H. F. Smith
Url: http://www.soest.hawaii.edu/pwessel/gshhg/