Provided by: grass-doc_7.8.2-1build3_all bug

GRASS GIS Quickstart

Geographic Resources Analysis Support System

       GRASS  GIS,  commonly  referred  to  as  GRASS  (Geographic Resources Analysis Support System), is a free
       Geographic Information System (GIS) software used for geospatial  data  management  and  analysis,  image
       processing, graphics/maps production, spatial modeling, and visualization. GRASS GIS is currently used in
       academic and commercial settings around  the  world,  as  well  as  by  many  governmental  agencies  and
       environmental  consulting  companies.  GRASS  GIS  is  an  official project of the Open Source Geospatial
       Foundation (OSGeo).

1. Graphical startup of GRASS GIS

       For text-based startup see below.

       After launching GRASS GIS, the startup screen will open:

    Selecting the GIS Database directory
       GRASS data are stored in a directory referred to as DATABASE (also called  "GISDBASE").   This  directory
       has  to  be created with a file manager or the mkdir command, before starting to work with GRASS.  Within
       this DATABASE, the projects are organized by project areas stored in subdirectories called LOCATIONs.

    Selecting the LOCATION (a project)
       A LOCATION is defined  by  its  coordinate  system,  map  projection  and  geographical  boundaries.  The
       subdirectories  and  files  defining a LOCATION are created automatically when GRASS is started the first
       time with a new LOCATION. It is important to understand that each projection stays in its own LOCATION.

       See the "Location Wizard"  to easily create a new LOCATION from scratch from a geocoded file, by defining
       the parameters or by selecting the corresponding EPSG projection code.

       See  to directly download a sample LOCATION into the DATABASE.

    Selecting the MAPSET (a subproject)
       Each LOCATION can have many MAPSETs. Each MAPSET is a LOCATION’s subdirectory. New MAPSET can be added at
       GRASS startup (see related button).

    Location Wizard
       The "Location Wizard" let’s you easily create a new LOCATION. You will be  guided  through  a  series  of
       dialogues  to  browse  and  select  predefined  projections  (also via EPSG code) or to define individual
       projections. You can also create new LOCATION easily from a georeferenced data file (e.g., SHAPE file  or
       GeoTIFF,  see  below).   Find  below  also  some  rules to define the default raster resolution for a new
       LOCATION.

    Download a sample LOCATION
       In the "Location Wizard" there is also  a  Download  button  that  allows  you  to  directly  download  a
       ready-to-use  LOCATION  into  the  DATABASE.  You  can  choose  among different sample LOCATIONS that are
       currently available at the Download section in the GRASS GIS website.

    Start GRASS
       Once you have selected an existing LOCATION/MAPSET or defined  a  new  one,  you  can  enter  GRASS.  The
       graphical  user  interface  wxGUI  will  open and provide you with a menu system, map visualization tool,
       digitizer, and more.

2. Background: GRASS GIS Location structure

       A LOCATION is simply a set of directories which contains  the  GRASS  data  of  a  project.  Within  each
       LOCATION,  a  mandatory  "PERMANENT"  MAPSET  exists  which contains projection information and some more
       definitions. It can be used to store the base cartography in it as "PERMANENT" is visible  to  all  users
       accessing a LOCATION.

       Fig. 1: GRASS GIS 7 location structure

   Creating and maintaining MAPSETs
       One  motivation  to  maintain different MAPSETs is to store maps related to project issues or subregions.
       Another motivation is to support simultaneous access of several users to the map layers stored within the
       same  LOCATION,  i.e. teams working on the same project. For teams, a centralized GRASS DATABASE would be
       defined in a shared network file system (e.g. NFS). Besides access to his/her own MAPSET, each  user  can
       also  read  map  layers  in  other  users’  MAPSETs, but s/he can modify or remove only the map layers in
       his/her own MAPSET.

       You can learn more about mapsets and how to seamlessly access maps found in another MAPSET  of  the  same
       LOCATION in the g.mapsets documentation.

   The role of the "PERMANENT" MAPSET
       When creating a new LOCATION, GRASS GIS automatically creates a special MAPSET called PERMANENT where the
       core data for the project can be stored. Data in the PERMANENT MAPSET can  only  be  added,  modified  or
       removed  by  the  owner of the PERMANENT MAPSET; however, they can be accessed, analyzed, and copied into
       their own MAPSET by the other users. The PERMANENT MAPSET is useful for providing  general  spatial  data
       (e.g.  an  elevation  model),  accessible  but  write-protected  to all users who are working in the same
       LOCATION as the database owner.  To manipulate or add data to PERMANENT, the owner would start GRASS  and
       choose  the relevant LOCATION and the PERMANENT MAPSET.  This mapset also contains the DEFAULT_WIND file,
       which holds the default region boundary coordinate values for the LOCATION (which all users will  inherit
       when  they  start  using the database). Additionally, in all mapsets a WIND file is kept, for storing the
       current boundary coordinate values and the currently selected raster resolution.  Users have  the  option
       of switching back to the default region at any time.

3. Creating a GRASS Database with Sample Data

       To create the GRASS database:

       1      Find  a place on your disk where you have write access and that has enough disk space to hold your
              spatial data.

       2      Create a subdirectory that will hold the general GRASS database (e.g. using a file manager or with
              mkdir /data/grassdata or mkdir /home/yourlogin/grassdata).

       Sample  data  such  as  the  "North  Carolina"  or the "Spearfish" sample datasets may be downloaded from
       http://grass.osgeo.org/download/sample-data/ and the compressed data package(s) extracted into  this  new
       database directory.

       Now  you  are  ready to select a sample dataset in the GRASS GIS startup screen (see above) and start the
       session.

4. Creating a New Location with the Location Wizard

       The wxGUI graphical user interface provides a graphical "Location Wizard" which lets you easily create  a
       new  LOCATION  for  own  data.  You  will  be  guided  through a series of dialogues to browse and select
       predefined projections (also via EPSG code) or to define individual projections. The rules to define  the
       resolution as described above also apply here.

       Hint: You can create new LOCATION easily from a georeferenced data file (e.g., SHAPE file or GeoTIFF file
       with the related metadata properly included).  In this case you are asked whether the data itself  should
       be imported into the new LOCATION. The default region is then set to match imported map and the GRASS GIS
       session is opened.

       After defining new LOCATION, wxGUI starts automatically.  If data were already imported, you can add them
       into  the Layer Manager now and display them. If your LOCATION is empty you can import your data from the
       menu: Go to "File" -> "Import raster/vector data" (see also the related Wiki page on Importing data).

5. Text-based startup and location creation

       GRASS GIS can be run entirely without using the graphical user interface.  For a first time startup,  the
       following steps have to be followed:

       1      Create a GRASS GIS database as explained above.

       2      Create a new location, including it’s default PERMANENT mapset, without entering the new location:

           •   Using an EPSG code:
                grass78 -e -c EPSG:32630 /home/user/grassdata/mylocation

           •   Using a georeferenced raster or vector file:
                grass78 -e -c MyGeoReferenceFile.tif /home/user/grassdata/mylocation

       3      Create new mapset within the new location and launch GRASS GIS within that mapset:
               grass78 -c /home/user/grassdata/mylocation/mymapset

Further Reading

       Please    have    a    look    at    the    GRASS    GIS    web    site    for   tutorials   and   books:
       http://grass.osgeo.org/documentation/.

See also

        GRASS GIS 7 Reference Manual
       GRASS GIS 7 startup program manual page

       List of EPSG codes (Database of worldwide coordinate systems)

       Main index | Topics index | Keywords index | Graphical index | Full index

       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual