Strumenti generali¶

Visualizzazione in funzione della scala¶

La visualizzazione in funzione della scala permette di specificare la scala minima e massima alla quale il vettore verrà visualizzato. Per impostare questa funzionalità, apri la finestra Proprietà facendo doppio click sul vettore. Nella scheda Generale, clicca sulla casella di controllo Visualizzazione dipendente dalla scala: potrai cosi inserire i valori minimi e massimi di visualizzazione della scala.

You can determine the scale values by first zooming to the level you want to use and noting the scale value in the QGIS status bar.

Controllare la visualizzazione della mappa¶

Map rendering can be controlled in the various ways, as described below.

Measure length, areas and angles¶

^{Measure Line}: QGIS is able to measure real distances between given points according to a defined ellipsoid. To configure this, choose menu option Settings ‣ Options, click on the Map tools tab and select the appropriate ellipsoid. There, you can also define a rubberband color and your preferred measurement units (meters or feet) and angle units (degrees, radians and gon). The tool then allows you to click points on the map. Each segment length, as well as the total, shows up in the measure window. To stop measuring, click your right mouse button. Note that you can interactively change the measurement units in the measurement dialog. It overrides the Preferred measurement units in the options. There is an info section in the dialog that shows which CRS settings are being used during measurement calculations.

Figure Measure 1:

Measure Distance (Gnome)

^{Measure Area}: Areas can also be measured. In the measure window, the accumulated area size appears. In addition, the measuring tool will snap to the currently selected layer, provided that layer has its snapping tolerance set (see section Settare la tolleranza dello snapping e il raggio di ricerca degli elementi). So, if you want to measure exactly along a line feature, or around a polygon feature, first set its snapping tolerance, then select the layer. Now, when using the measuring tools, each mouse click (within the tolerance setting) will snap to that layer.

Figure Measure 2:

Measure Area (Gnome)

^{Measure Angle}: You can also measure angles. The cursor becomes cross-shaped. Click to draw the first segment of the angle you wish to measure, then move the cursor to draw the desired angle. The measure is displayed in a pop-up dialog.

Figure Measure 3:

Measure Angle (Gnome)

Selezionare e deselezionare elementi¶

The QGIS toolbar provides several tools to select features in the map canvas. To select one or several features, just click on and select your tool:

• ^{Select Single Feature}
• ^{Select Features by Rectangle}
• ^{Select Features by Polygon}
• ^{Select Features by Freehand}
• ^{Select Features by Radius}

To deselect all selected features click on ^{Deselect features from all layers}.

^{Select feature using an expression} allow user to select feature using expression dialog. See Expressions chapter for some example.

Users can save features selection into a New Memory Vector Layer or a New Vector Layer using Edit ‣ Paste Feature as ... and choose the mode you want.

Reticolo¶

^Reticolo ti permette di aggiungere un reticolo e le coordinata alla mappa.

Figure Decorations 1:

The Grid Dialog

1. Seleziona dal menu Visualizza ‣ Decorazioni‣ Reticolo. Si aprirà un`altra finestra (vedi figure_decorations_1).

2. Attiva la casella di controllo Abilita reticolo e imposta i valori che preferisci in funzione dei layer caricati sulla mappa.

3. Attiva la casella di controllo Scrivi coordinate e imposta le proprietà migliori in base agli elementi che hai caricato sulla mappa.

4. Click [Apply] to verify that it looks as expected.
5. Click [OK] to close the dialog.

Etichetta Copyright¶

^{Copyright label} adds a copyright label using the text you prefer to the map.

Figure Decorations 2:

The Copyright Dialog

1. Seleziona dal menu Visualizza ‣ Decorazioni‣ Etichetta copyright. Si aprirà un`altra finestra (vedi figure_decorations_2).

2. Digita il testo che vuoi aggiungere alla mappa. Puoi anche usare il linguaggio HTML come mostrato nell’esempio.

3. Choose the placement of the label from the Placement combo box.

4. Assicurati che la casella di controllo Abilita etichetta di copyright sia spuntata.

5. Click [OK].

In the example above, which is the default, QGIS places a copyright symbol followed by the date in the lower right-hand corner of the map canvas.

Freccia Nord¶

^{North Arrow} places a simple north arrow on the map canvas. At present, there is only one style available. You can adjust the angle of the arrow or let QGIS set the direction automatically. If you choose to let QGIS determine the direction, it makes its best guess as to how the arrow should be oriented. For placement of the arrow, you have four options, corresponding to the four corners of the map canvas.

Figure Decorations 3:

The North Arrow Dialog

Barra di Scala¶

^{Scale Bar} adds a simple scale bar to the map canvas. You can control the style and placement, as well as the labeling of the bar.

Figure Decorations 4:

The Scale Bar Dialog

QGIS only supports displaying the scale in the same units as your map frame. So if the units of your layers are in meters, you can’t create a scale bar in feet. Likewise, if you are using decimal degrees, you can’t create a scale bar to display distance in meters.

Per aggiungere una barra di scala:

1. Seleziona dal menu Visualizzazione ‣ Decorazioni‣ Barra di scala. Si aprirà cosi una finestra di dialogo (see figure_decorations_4)

2. Choose the placement from the Placement combo box.
3. Choose the style from the Scale bar style combo box.
4. Select the color for the bar Color of bar or use the default black color.
5. Set the size of the bar and its label Size of bar .

6. Assicurati che la casella di controllo Abilitare barra di scala sia spuntata.

7. Optionally, check Automatically snap to round number on resize.
8. Click [OK].

Note Html¶

The ^{Html Annotation} tools in the attribute toolbar provides the possibility to place the content of an html file in a balloon on the QGIS map canvas. Using the Html Annotation tool, click into the map canvas and add the path to the html file into the dialog.

Note SVG¶

The ^{SVG Annotation} tool in the attribute toolbar provides the possibility to place an SVG symbol in a balloon on the QGIS map canvas. Using the SVG Annotation tool, click into the map canvas and add the path to the SVG file into the dialog.

Modulo annotazioni¶

Additionally, you can also create your own annotation forms. The ^{Form Annotation} tool is useful to display attributes of a vector layer in a customized Qt Designer form (see figure_custom_annotation). This is similar to the designer forms for the Identify features tool, but displayed in an annotation item. Also see this video https://www.youtube.com/watch?v=0pDBuSbQ02o from Tim Sutton for more information.

Figure annotation 2:

Customized qt designer annotation form

Creazione di un segnalibro¶

Per creare un segnalibro:

1. Usa lo zoom o muovi la mappa all’estensione d’interesse.

2. Select the menu option View ‣ New Bookmark or press Ctrl-B.

3. Inserisci un nome descrittivo per il segnalibro (fino a 255 caratteri).

4. Press Enter to add the bookmark or [Delete] to remove the bookmark.

Nota che puoi avere più di un segnalibro con lo stesso nome.

Uso e gestione dei segnalibri¶

To use or manage bookmarks, select the menu option View ‣ Show Bookmarks. The Geospatial Bookmarks dialog allows you to zoom to or delete a bookmark. You cannot edit the bookmark name or coordinates.

Zooming to a Bookmark¶

From the Geospatial Bookmarks dialog, select the desired bookmark by clicking on it, then click [Zoom To]. You can also zoom to a bookmark by double-clicking on it.

Deleting a Bookmark¶

To delete a bookmark from the Geospatial Bookmarks dialog, click on it, then click [Delete]. Confirm your choice by clicking [Yes], or cancel the delete by clicking [No].

Import or export a bookmark¶

To share or transfer your bookmarks between computers you can use the Share pull down menu in the Geospatial Bookmarks dialog.

Layers inclusi¶

La finestra di dialogo ti permette di scegliere quali layer di altri progetti puoi includere. Di seguito un piccolo esempio:

1. Press to look for another project from the Alaska dataset.
2. Select the project file grassland. You can see the content of the project (see figure_embed_dialog).
3. Press Ctrl and click on the layers grassland and regions. Press [OK]. The selected layers are embedded in the map legend and the map view now.

Figure Nesting 1:

Select layers and groups to embed

Anche se i layer nidificati sono modificabili, non puoi modificarne le proprietà, come stile ed etichette.

Rimuovi i layer nidificati¶

Right-click on the embedded layer and choose ^Remove.