Noriel Christopher C' Tiglao, Dr' Eng

1
Introduction to GRASS
Module 5

• Noriel Christopher C. Tiglao, Dr. Eng
• 24 January 4 February 2005
• Statistical Research and Training Center (SRTC)
• Quezon City, Metro Manila

2
Presentation Outline

• Open Source Concept
• Getting Started with GRASS
• Command Structure
• GRASS File Management

3
Open Source Concept

• For freedoms of Free Software (Richard M.
  Stallman)
• The freedom to run the program, for any purpose
• The freedom to study how the program works, and
  adapt it to your needs
• The freedom to redistribute copies
• The freedom to improve the program, and release
  your improvements to the public, so that the
  whole community benefits

Founder of the Free Software Foundation in 1985
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Open Source Concept (contd.)

• The GNU General Public License (GPL) not only
  grants the four freedoms but also protects them
• http//www.gnu.org
• The license protects contributors against misuse
  of their code contribution within proprietary
  projects which do not allow free access to their
  source code
• GPL is the most widely used license for Free
  Software

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Open Source Concept (contd.)

• Based on the assumption that by allowing the
  programmers to read, redistribute, and modify the
  source code, the software evolves
• Software gets improved, software errors (often
  called bugs) are fixed and capabilities
  expanded
• Full access to the source code is particularly
  important for GIS because the underlying
  algorithms can be complex and can greatly
  influence the results of spatial analysis and
  modeling

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Open Source Concept (contd.)

• While an average user may not be able to trace
  bugs within a complex source code, there is a
  number of specialists willing to test, analyze
  and fix the code
• The different backgrounds and expertise of these
  developers contribute to the synergistic effects
  leading to faster and more cost effective
  software development of a stable and robust
  product
• Open source development is very dynamic

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GRASS as an Open Source GIS

• Geographical Resources Analysis Support System
• A raster/vector GIS combined with integrated
  image processing and data visualization
  subsystems
• Includes more than 350 modules for management,
  processing, analysis and visualization of
  georeferenced data

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GRASS as an Open Source GIS

• Geographical Resources Analysis Support System
• A raster/vector GIS combined with integrated
  image processing and data visualization
  subsystems
• Includes more than 350 modules for management,
  processing, analysis and visualization of
  georeferenced data

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GRASS as an Open Source GIS

• GPL offers GRASS users various advantages
• Full access to the source code
• Low costs
• Access to new features and capabilities developed
  between the releases
• Possibility to provide release more often that it
  is common for proprietary products

10
GRASS Development Model
WWW/FTP GRASS-releases Documents Sample data
Mailing lists
CVS Source code
RT bugtracker
INTERNET
Users
Developers
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GRASS Development

• GRASS Development Team is coordinate at ITC-irst
  Centro per la Ricerca Scientifica e
  Tecnologica, Trento (Italy)
• GRASS Website http//grass.itc.it

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GRASS GIS Functionality
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GRASS GIS Functionality (contd.)
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GRASS GIS Functionality (contd.)
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Available platforms

• Linux
• SUN
• SGI
• MacOS X
• MS-Windows NT/2000/XP (requires the Cygwin tools)

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Organization of the GRASS Database
/usr/local/share/grassdata
DATABASE
ncarolina-ll/
ncarolina-utm/
trentino-gb/
LOCATIONS
PERMANENT/ helena/ user2/
PERMANENT/ user2/
PERMANENT/ helena/ markus/
MAPSETS
Map layers
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GRASS Database

• DATABASE (also called GISDBASE)
• UNIX directory which contains GRASS data
• Locations
• Defined by its coordinate system, map projection
  and geographical boundaries
• Can have several MAPSETS
• MAPSETS
• PERMANENT MAPSET can be added, modified or
  removed by the owner can be accessed, analyzed
  and copied by other users

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GRASS Database (contd.)

• PERMANENT MAPSET is useful in providing general
  spatial data write-protected to other users who
  are working in the same LOCATION
• This PERMANENT MAPSET contains the DEFAULT_WIND
  file which holds the default region boundary
  coordinate values
• In all mapsets, a WIND file is kept for storgin
  current boundary coordinate values and the
  currently selected raster resolution

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GRASS Modules

• Are organized by name, based on their function
  class
• Display
• General
• Imagey
• Raster
• Vector
• Site
• The first level refers to the function class,
  followed by a dot and one or two works, again
  separated by dots

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General Syntax

• module -flag1 flag2\ parameter1map1
  ,map2,\ parameter2number
• module is the name of the command
• optional flags enable specific features
• parameters are names of input or output files or
  may be a constant or name of a method, symbol
  etc.
• Note there must be no space when listing
  comma-separated names

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GRASS Module Function Classes
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To run GRASS under Cygwin

• Double-click the Cygwin icon from the desktop
• Type startxwin.bat to start the X-Windows program

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To run GRASS under Cygwin (contd.)

• From the X-Windows shell, type grass57 then
  Enter to start GRASS program

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Database Selection and Creation
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GRASS Command Line Interface
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GRASS Display Manager
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GRASS Monitor
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GRASS Menu System

• To run TclTkGRASS, type
• tcltkgrass

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GRASS running on Windows XP
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Listing available data

• To list available vector, raster and site data
  layers, type
• g.list rast
• g.list vect
• g.list sites
• Alternatively, in TclTkGRASS, select under MAP
  LIST RASTER Run

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Displaying information about each layer

• r.info soils
• v.info streams
• s.info archsite

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Opening a GRASS monitor

• d.mon x0
• In TclTkGRASS, select DISPLAY MONITOR START
  X0

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To view layers

• d.rast soils
• d.vect streams colblue
• d.sites archsites colwhite typebox

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To exit GRASS

• Type
• exit
• Close all monitors and other relevant windows

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To display map layers with titles

• g.list f vect
• g.list f vect mapsetPERMANENT
• G.mlist typevect patternr

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To copy a map layer

• g.copy
• Specify the map type and add an old a new map
  name
• g.copy vectrailroads_at_PERMANENT,myrailroads

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To rename a map layer

• g.rename
• Specify the map type and add an old a new map
  name
• g.rename vectmyrailroads,railnetwork

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To remove a map layer

• g.remove
• g.rename vectrailnetwork

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To remove multiple map layers

• g.mremove
• g.copy vectrailroads_at_PERMANENT,myrailroads1
• g.copy vectrailroads_at_PERMANENT,myrailroads2
• g.copy vectrailroads_at_PERMANENT,myrailroads3
• g.list vect
• g.mremove vectmyrail

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To add other MAPSETS to the MAPSET SEARCH PATH

• g.mapsets
• Toggle all available MAPSETS
• Type
• g.mapsets

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To copy a LOCATION

• To copy a LOCATION or even a complete GRASS
  database directory, package the directories and
  extract them in the destination directory
• cd /usr/lcoal/share/grassdata
• tar cvfz myspearfish_location.tar.gz spearfish
• mv myspearfish_location.tar.gz target_directory/
• cd target_directory
• tar xvfz myspearfish_location.tar.gz

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To remove a LOCATION

• cd /usr/local/share/grassdata
• rm r spearfish

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Starting GRASS with a new project
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Starting GRASS with a new project(text-based
interface)
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Compiling data

• If we have data in different coordinate systems,
  we have to import and store them in different
  LOCATIONs. However, the data can be re-projected
  between these LOCATIONs using the GRASS
  projection modules

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End