General Tools¶

Scale Dependent Rendering¶

Scale dependent rendering allows you to specify the minimum and maximum scales at which a layer will be visible. To set scale dependency rendering, open the Properties dialog by double-clicking on the layer in the legend. On the General tab, set the minimum and maximum scale values and then click on the Use scale dependent rendering checkbox.

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.

Controlling Map Rendering¶

Map rendering can be controlled in the following ways:

Measure length, areas and angles¶

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 choose 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 tools 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.

Figure Measure 1:

Measure Distance (KDE)

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 Setting the Snapping Tolerance and Search Radius). 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 (KDE)

You can also measure angles, selecting Measure Angle tool. The cursor becomes cross-shaped. Click to draw the first segment of the angle you wish to measure, then move the the cursor to draw the desired angle. The measure is displayed in a popup dialog.

Figure Measure 3:

Measure Angle (KDE)

Select and deselect features¶

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}.

Copyright Label¶

Copyright label adds a Copyright label using the text you prefer to the map.

Figure Decorations 1:

The copyright Dialog

1. Select from menu View ‣ Decorations ‣ Copyright Label. The dialog starts (see figure_decorations_1).
2. Enter the text you want to place on the map. You can use HTML as shown in the example
3. Choose the placement of the label from the Placement ‘Bottom Right’ drop-down box
4. Make sure the Enable Copyright Label checkbox is checked
5. Click [OK]

In the example above (default) QGIS places a copyright symbol followed by the date in the lower right hand corner of the map canvas.

North Arrow¶

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 2:

The North Arrow Dialog

Scale Bar¶

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

Figure Decorations 3:

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.

To add a scale bar:

1. Select from menu View ‣ Decorations ‣ Scale Bar The dialog starts (see figure_decorations_3)
2. Choose the placement from the Placement ‘Bottom Left’ drop-down list
3. Choose the style from the Scale bar style ‘Tick Down’ list
4. Select the color for the bar Color of bar ‘black’ or use the default black color
5. Set the size of the bar and its label Size of bar ‘30 degrees’
6. Make sure the Enable scale bar checkbox is checked
7. Optionally choose to automatically snap to a round number when the canvas is resized Automatically snap to round number on resize
8. Click [OK]

Form annotations¶

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). It is similar to the designer forms for the Identify features tool, but displayed in an annotation item. Also see QGIS blog http://blog.qgis.org/node/143 for more information.

Figure annotation 2:

Customized qt designer annotation form

Creating a Bookmark¶

To create a bookmark:

1. Zoom or pan to the area of interest.
2. Select the menu option View ‣ New Bookmark or press Ctrl-B.
3. Enter a descriptive name for the bookmark (up to 255 characters).
4. Press Enter to add the bookmark or [Delete] to remove the bookmark.

Note that you can have multiple bookmarks with the same name.

Working with Bookmarks¶

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 can not 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].

Embedding layers¶

The following dialog allows you to embed layers from other projects:

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 klick on the layers grassland and regions. The layers are embedded in the map legend and the map view now.

Figure Nesting 1:

Select layers and groups to embed

While the embedded layers are editable you can’t change it’s properties like Style and Labeling.

Removing embedded layers

Right-click on the embedded layer and choose Remove .