5. Noțiuni de bază
This chapter provides a quick overview of installing QGIS, downloading QGIS sample data, and running a first simple session visualizing raster and vector data.
QGIS project provides different ways to install QGIS depending on your platform.
For more information and instructions for your operating system check https://download.qgis.org.
If you need to build QGIS from source, please refer to the installation
instructions. They are distributed with the QGIS source code in a file
INSTALL. You can also find them online at https://github.com/qgis/QGIS/blob/release-3_22/INSTALL.md.
If you want to build a particular release and not the version in development,
you should replace
master with the release branch (commonly in the
release-X_Y form) in the above-mentioned link (installation instructions may differ).
It is possible to install QGIS (with all plugins and settings) on a flash drive. This is achieved by defining a –profiles-path option that overrides the default user profile path and forces QSettings to use this directory, too. See section System Settings for additional information.
This user guide contains examples based on the QGIS sample dataset (also called
Alaska dataset). Download the sample data from
https://github.com/qgis/QGIS-Sample-Data/archive/master.zip and unzip the archive
on any convenient location on your system.
Setul de date Alaska cuprinde toate datele GIS care stau la baza exemplelor și a capturilor de ecran din ghidul utilizatorului. Este inclusă, de asemenea, o mică bază de date GRASS. Proiecția datelor eșantion pentru setul de date QGIS este Alaska Albers cu Suprafețe Egale, unitățile de măsura fiind picioarele. Codul EPSG este 2964.
PROJCS["Albers Equal Area", GEOGCS["NAD27", DATUM["North_American_Datum_1927", SPHEROID["Clarke 1866",6378206.4,294.978698213898, AUTHORITY["EPSG","7008"]], TOWGS84[-3,142,183,0,0,0,0], AUTHORITY["EPSG","6267"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9108"]], AUTHORITY["EPSG","4267"]], PROJECTION["Albers_Conic_Equal_Area"], PARAMETER["standard_parallel_1",55], PARAMETER["standard_parallel_2",65], PARAMETER["latitude_of_center",50], PARAMETER["longitude_of_center",-154], PARAMETER["false_easting",0], PARAMETER["false_northing",0], UNIT["us_survey_feet",0.3048006096012192]]
If you intend to use QGIS as a graphical front end for GRASS, you can find a selection of sample locations (e.g., Spearfish or South Dakota) at the official GRASS GIS website, https://grass.osgeo.org/download/data/.
QGIS can be started like any other application on your computer. This means that you can launch QGIS by:
dublu clic pe pictograma din folderul Aplicațiilor sau pe o scurtătură de pe ecran.
double clicking an existing QGIS project file (with
.qgsextension). Note that this will also open the project.
qgisin a command prompt (assuming that QGIS is added to your PATH or you are in its installation folder)
To stop QGIS, use:
landcoverraster layer (
lakesvector layer (
qgis_sample_data represents the path to the unzipped dataset.
Start QGIS as seen in Starting and stopping QGIS.
To load the files in QGIS:
Browse to the folder
Select the ERDAS IMG file
landcover.imgand double-click it. The landcover layer is added in the background while the Data Source Manager window remains open.
To load the lakes data, browse to the folder
qgis_sample_data/gml/, and double-click the
lakes.gmlfile to open it.
A Coordinate Reference System Selector dialog opens. In the Filter menu, type
2964, filtering the list of Coordinate Reference Systems below.
Select the NAD27 / Alaska Albers entry
Clic pe OK
Close the Data Source Manager window
You now have the two layers available in your project in some random colours. Let’s do some customization on the lakes layer.
Zoom to an area with some lakes
lakeslayer in the map legend to open the Properties dialog
To change the lakes color:
To display the name of the lakes:
You can improve readability of the labels by adding a white buffer around them:
Let’s now add some decorations in order to shape the map and export it out of QGIS:
Customize the options of the dialog as you want
Likewise, from the decorations menu, add more items (north arrow, copyright…) to the map canvas with custom properties.
Press Save in the opened dialog
Select a file location, a format and confirm by pressing Save again.
That’s it! You can see how easy it is to visualize raster and vector layers in QGIS, configure them and generate your map in an image format you can use in other softwares. Let’s move on to learn more about the available functionality, features and settings, and how to use them.
To continue learning QGIS through step-by-step exercises, follow the Training manual.