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Introducción a los conceptos y a la utilización del SIG Open

1. four well known algorithms shortest path v net path e traveling salesman problem v net salesman Steiner tree v net steiner e sub net allocation v net alloc infojornadas sigte udg es D for Database Relational Databases db prefix stands for management of relational databases for instance to check available drivers to connect to a database to check the structure of the databases or of the tables and to modify this structure only if you have root permissions on this database Running SQL queries db execute db execute allows you to execute any SQL query within GRASS SELECT UPDATE ALTER DROP You can store these queries in a text file to call them back later easily These functions are only a small part of GRASS GIS capabilities new users are likely to try some of these functions while familiarizing themselves with the interface and the data CONCLUSION GRASS interfaces and functions have been slightly changing from GRASS 5 x to GRASS 6 x However GRASS core and base concepts mostly remained the same and are known to be the biggest obstacle for beginners Other steps are still needed to make GRASS more accessible and a more main stream GIS software the i18n project consists in translating GRASS messages and tk interface to various widely spoken languages the redaction and translation of documentation tutorials and GRASS 6 x official manual Through OSGeo Free GIS projects are now aiming to
2. Libres por ejemplo GvSIG parecen m s populares en la Comunidad Hispanohablante nos detendremos en las necesidades de traducci n de las diferentes interfaces gr ficas y de la documentaci n y tambi n en los recursos disponibles para participar Palabras clave base de datos geogr ficos GRASS GIS Comunidad Hispano hablante gesti n de utilizadores interfaz gr fica infojornadas sigte udg es ABSTRACT In this presentation we would like to focus on GRASS GIS version 5 x and the latest 6 x one of the oldest GIS developped by the Open Source Community Our goal is trying to make it accessible to any GIS user by explaining its main concepts After a couple of technical considerations on using GRASS on various operating systems such as Unix Linux Windows with or without Cygwin or MacOsx onthe choice among the differents graphical interfaces available the classical Tcl Tk QGIS JGrass and on its connection with other open source projects such as GDAL OGR Proj4 or PostgreSQL we will describe a typical first launch and the creation of a geographic database First we will detail the management of the projection and coordinate systems of data through the Location Then we will review the management of users and read write permissions Unix like within Mapset s Finally we will explain the original concept of Region to cope with the focus and resolution of data layers both for visu
3. RASS automatically launches a web browser to display man page in html format This help page provides details on command use with the different flags and options available anextended description of the context of use of the command very often examples of use authors of the module and date of last update Calling concise help within Shell You can also call concise help for any command contents are displayed in GRASS shell bar foo bone help Concise help includes a short description of the command the correct way to use it where flags should be typed with a minus sign for instance d rast o non optional parameters are presented without brackets like d rast map a_raster_map optional parameters are presented with brackets parameters where the input can be a list of values and the separator for instance commas or semi colons The meaning of these different options with possible restrictions for instance raster size limitation on various operations G for GRASS general tasks regarding users and data management GRASS general commands are needed to change the current mapset g mapset or the current region g region and also to modify data layers renaming them g rename old_name new_name copying them g copy or dumping them g remove infojornadas sigte udg es g access command allows to manage read write permissions for users or groups on mapsets Getting a list of av
4. SERVEI DE SISTEMES D INFORMACI GEOGR FICA TELEDETECCIO Universitat de Girona JORNADAS DE SIG LIBRE Introduccion a los conceptos y a la utilizacion del SIG Open Source GRASS E Rousseau 1 GRASS Users Community GRASS French Translations Team eve rousseau gmail com RESUMEN En este informe queremos presentar el SIG GRASS en sus versiones 5 x y 6 x uno de los SIG m s antiguos desarrollado en la Comunidad Open Source El objetivo perseguido se resume explicando a cualquier utilizador de SIG las especificaciones conceptuales de GRASS eS de unas consideraciones t cnicas a prop sito de a la utilizaci n de GRASS en varios sistemas tales como Unix Linux Windows con Cygwin o sin y MacOSX b la elecci n de una interfaz gr fica la cl sica Tcl Tk QGIS o JGRASS c las interacciones funcionales entre GRASS y otros proyectos Open Source como GDAL OGR Proj4 o PostgreSQL describiremos un primer arranque t pico con la creaci n de un base de datos geogr ficos Primero se tratar de la gesti n de las proyecciones y sistemas de coordenadas a trav s del concepto de Location Luego de la gesti n de los utilizadores y de sus autorizaciones tales como en el modelo Unix de lectura escritura en los datos con los Mapset s Por fin veremos c mo ajustar la Region a la vez para el enfoque del zoom y la resoluci n de los mapas para la visualizaci n y el proceso de datos Como otros SIG
5. ailable data layers g list and g mlist g list allows you to know layers available for a given data type like raster vector or raster3D g mlist is designed to search for a text pattern like part of a layer name or to use a regular expression to list available map layers Like usual the character stands for the unknown part of the layer name for instance NikoR for any layer beginning with the string NikoR Landsat for all layer names ending with the string Landsat 1995 for all layer names including the string 1995 We cannot stress too much the need to normalize layer names so that any database user might run these queries Normalization could be not using accents tildes or spaces in the layer name Clearly stating as an abbreviation the type of satellite used for remote sensing images i e Spot1 adding as the name or the initial letters of the name of the cartographer for analysis or synthesis layers indicating the date when the data was initially created at least the year of creation or a more precise timestamp AAMMJJ HHMM Using normalized geographical names for instance only local spellings of the toponyms or only English transpositions of the toponyms using capital letters or normal letters to clearly distinguish between finalized data layers and work in progress layers of course these are only suggestions D for Display display commands Commands be
6. alisation and data processing Considering that other Free GIS for instance GvSIG might be more popular and deeply rooted in Spanish speaking countries we will discuss the needs of GRASS user community regarding translation of various interfaces and documentation and the tools presently available to contribute Key words geographical database graphical interface GRASS GIS Spanish speaking community users management INTRODUCTION With its last version 6 x GRASS which stands for Geographic Resources Analysis Support System can fully compete with other commercial GIS softwares Indeed the original GRASS 5 raster and image processing functionalities are completed with a new vectorial engine Also integration with other OpenSource softwares and libraries like GDAL for raster files import export OGR for vector files import export PostgreSQL and its module PostGIS for relational and spatial database management and portable and modular interfaces JGRASS written in Java or QGIS written in Qt etc made GRASS a more mature and user friendly GIS software With the help of pre compiled GRASS binaries for various Linux distributions c f Debian GIS Ubuntu GIS projects but also packages for Suse Mandriva Fedora or with the long awaited QGIS 0 8 Titan which includes GRASS GIS functionnalities vector and raster processing GDAL and OGR import export it is now much easier infojornadas sigte udg
7. es to get it running properly However beginners remain puzzled by a couple of specific GRASS concepts These main concepts are the geographical database the Location the region and the mapset In what follows we will try to guide you through a first start with GRASS Definition and practical use of GRASS main concepts These concepts should be useful if you are launching GRASS 5 x or 6 x for the first time in its classical configuration classical meaning GRASS Tk interface under Linux or Cygwin for instance or if you are opening a GRASS session within QGIS 0 8 You will be prompted with questions regarding the database Location region and mapset GRASS GIS needs you to define those parameters before you can proceed with data integration visualization or processing Creating a GRASS Geographical Database After installing GRASS you will need to create an empty directory on your hard disk to store your Geographical Database and work upon them with GRASS Usually it is called grassdata or gisdata Remember not to put any accents tildes or spaces in the directories or files names For a first start you could unzip Spearfish Database freely downloadable on GRASS website in this directory Spearfish is a Geographical Database centered on a national park in South Dakota made world famous by its monument the faces of four American presidents carved in the rock The database contains vector layers road ne
8. ginning with d gather display commands including raster layers d rast vector layers d vect but also barscales d barscale histograms d histogram or any graphical object that can be added on the map display d mon manage monitors GRASS monitors there are seven of them x0 x1 x6 are a peculiarity of GRASS 5 and GRASS6 tcl tk interface Their advantage is that you might display simultaneously various views on your data selected layers zoom level resolution etc To start select or stop these monitors you will use respectively d mon start x2 d mon select x1 and d mon stop x6 If needed monitors can be resized using d monsize PS for PostScript a map publishing module ps map is the one and only command in the ps family but it includes the classical GRASS map publishing module You can feed GRASS shell scripts made of several GRASS display command lines through this command to semi automize map production Examples of such scripts can be found in GRASS manuals infojornadas sigte udg es I for Image image analysis and image processing i gathers all the usual commands of image processing including image rectification Fast Fourier Transform and Inverse Fast Fourier Transform Brovey transform PCA and CCA supervised and non supervised classification etc Michael Shapiro s tutorial 4 states all image processing functionalities and their context of use A special sub family i ortho photo
9. i ortho photo aims precisely ortho photographic rectification lts dedicated commands start with i photo R for Raster Raster layers and their specific processing functions are the widest family of commands in GRASS There you will find support for statistical analysis raster processing and raster creation Map algebra r mapcalc r mapcalc allows the user to carry on algebrical operations on the contents of one or several raster layers This particular module has many functionalities masks creation map generation use of complex operators and conditional clauses etc therefore it is highly recommended to read its documentation to use it properly R3 for Raster3D 3D raster layers won t use the same modules as 2D raster files prefix for these commands is r3 Watch out carefully what is the 3D grid resolution before you start working on 3D rasters and modify it accordingly if necessary same region configuration problem as when you are working on 2D rasters V for Vector Native GRASS vector format and vector libraries have been entirely redesigned in the shift from GRASS 5 x to GRASS 6 x You will find classical modules of vector layer processing starting with the digitalization of vector layers v digit cropping one layer using another layer v overlay connexion to attribute data tables etc A sub family for network analysis v net GRASS 6 performs through the v net family of functions network analysis with
10. n mapsets in GRASS exactly like on UNIX directories Tabla 1 the data within a personal mapset can be completly private read write permissions for you only or available for a group etc These permissions can be modified using g mapset Table 1 examples of permission granting on different mapsets Groups of Ciudad de Ciudad de C A de users Girona Barcelona Catalunya Mapsets Girona Read Write Read Read Write Barcelona Read Read Write Read Write Catalunya Read Read Read Write infojornadas sigte udg es With Location default region and mapset s clearly defined you can start building up your GRASS project and working on your data layers GRASS functionnalities through several modules Using GRASS shell and calling for help GRASS manual is actually the one and only official source for using GRASS commands even if there are many tutorials available 1 2 and or redistributable under GNU Free Documentation License 3 There is one user manual for every GRASS version 5 4 5 7 6 0 and so on Calling GRASS manual web browser display Depending on the interface you are using you might call the manual from the menu in GIS Manager i e the classical interface or from the tab Manual of GRASS ToolBox for every command available within QGIS 0 8 GRASS Toolbox Anyway in all cases you can access manual pages directly by typing in GRASS shell g manual bar foo bone G
11. of your map layers to configure it the one with most extent is convenient see below on how to proceed then use g region p to know the parameters of your region If you fill new coordinates always make sure that North has a bigger value than South and East has a bigger value than West Figura 1 N s Figure 1 Region extent and NSWE coordinates The current region The region parameters can be modified whenever needed using the command g region The region extent and resolution can match the extent of any map layer g region rast my_raster_10m g region rast3D my_3d_raster g region vect streets_vector or mapset g region mapset low_resolution_mapset Creating a mapset PERMANENTS mapsets First of all GRASS automatically creates a mapset called PERMANENT it contains layer maps with read permissions for any user and write permissions only for the database administrator Generally we store in the PERMANENT mapset the original data to be processed like Numerical Data Models remote sensing images ground data truth You can create many PERMANENT mapsets just by writing their names in capital letters SPOT_IMAGES LANDSAT_IMAGES ANY_NAME It is useful to create several PERMANENTs mapsets when you have raster layers with different resolutions because each mapset holds its own region definition including raster resolution you can choose for each mapset an adequate configuration You can manage read write permissions o
12. twork rivers etc raster layers soil map geological map etc remote sensing images to provide a full sample of database layers processed in GRASS Creating a new Location The Location stores information on layers projection and coordinate system Therefore you can have a Location called World with data in UTM and another Location called France with data projected in Lambert Conforme Conical Whenever you start GRASS you can create a new Location either defining its parameters step by step ellipsoid datum parallels central meridian map units choose between meters or miles or using a shortcut like an EPSG code There are four types of Locations 1 XY Location for raw data raw remote sensing data medical data 2 Latitude Longitude Location 3 UTM Location 4 Location with other types of projections like Laborde Lambert and many others Creating a new region In GRASS what is displayed in the map monitor strictly matches what will be processed Therefore it is recommended to carefully define the default region and to modify it while working on maps whenever needed for instance you can slightly lower the resolution of images to speed up algorithms on raster maps and images infojornadas sigte udg es The default region The default region is defined when you create the Location The region is a rectangle with North South East and West coordinates if you are not sure use one
13. wards cross fertilization between developers teams and organisation of translators and users through local chapters ACKNOWLEDGEMENTS The author wishes to thank Suzanne LJ Lud J rome AMP Y for their advice and ideas and all the Faux Rhum team for its good humour REFERENCES ALONSO SARRIA F 2000 Tutorial de introduccion a GRASS 120pp NETELER M traducido por MARTINEZ G 2005 GRASS 6 una guia de inicio OpenSource Geospatial 05 Conference Junio 16 18 2005 University of Minnesota Minneapolis USA NETELER M DASSAU O HOLL S REDSLOB M 2006 GRASS Tutorial 1 2 GDF Hannover 170pp SHAPIRO M HARMON V 1995 GRASS Tutorial Image Processing U S Army Construction Engineering Research Laboratory 47pp infojornadas sigte udg es

Introducción a los conceptos y a la utilización del SIG Open

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Introducción a los conceptos y a la utilización del SIG Open