Creating a new location

Creating a location in Windows

1. Run "grass63.bat -tcltk" (to quit, type exit, answer y to "Terminate Batch Job"). "-tcltk" indicates you want to run the GUI.
2. a window should pop up. enter $MDIGROOT/gisdata as the "gis data directory" (or copy $MDIGROOT/gisdata to where you want to store grass gis files and use this new path). This data directory is where GRASS stores all it's gis data, metadata, projection information etc. You shouldn't store other types of GIS data in this directory, as it'll quickly become confusing. Think of it as a repository of information just for GRASS/MDiG. You can import GIS data from other systems into this directory later.
3. you should now see a project location "nzmg" - this is a predefined location with projection and datum information for the New Zealand Mapping Grid. It also has one mapset...
   • A word about locations/mapsets etc. The database is the directory to store GIS data in. Data has to be here for GRASS to access it, but there are commands for importing GIS data from elsewhere. The location "nzmg" defines the projection and geographic datum. Maps that are imported between locations are automatically projected, and certain types of external GIS files are projected when imported too. Each mapset is series of related maps. Usually the PERMANENT mapset is used for the original copies of source data maps, and other mapsets are created for each project (maps from each mapset can be accessed regardless of the working mapset, but the working mapset will be checked first.
4. To create a new location select one of the appropriate buttons under "Define new location with..."

Notes

When running large simulations with thousands of maps and different permutations of parameters, you can start hitting the limit of some file systems.

In particular, ext2/ext3 seem to have trouble as one reaches around 32000 files. Code to manage large numbers of output maps and better collate them is planned to be written soon. If you have the option, then Reiserfs handles large numbers of files well.