Here’s a summary of recent additions and updates to plugins in the QGIS repository.
FlowMapper (0.1.1) - Generates flow lines between discreet nodes for depicting spatial interaction data (e.g. migration). Query By Example (0.2) - Select features by location. Item Browser (1.6.0) - Browse a multiple selection with auto-zooming to feature and an option to open feature form. Custom Launcher (1.1.0) - Customize your own actions to launch your preferred apps or commands within QGIS.
This week we look at a newly arrived plugin named qNote. This plugin allows you to create a note and store it in a QGIS project file. When the project is loaded, the note is restored and can be viewed in the qNote panel.
This little plugin provides a way to attach metadata to a project. Things you might want to include in a note are:
Content of the project Purpose Area of interest Where the data came from Who created the project This information can be helpful when sharing a project or when you forget what you did six months after the fact.
This week we look at the OpenLayers plugin for QGIS. This plugin allows you to add a number of image services to your map canvas:
Google Physical Streets Hybrid Satellite OpenStreetMap Yahoo Street Hybrid Satellite Bing Road Aerial Aerial with labels Installing the Plugin The OpenLayers plugin is installed like all other Python plugins. From the the Plugins menu in QGIS, choose Fetch Python Plugins.
This week we take a look at a how to plot a terrain profile using the Profile plugin. The plugin can be used with any raster format supported by QGIS. You can can display profiles from up to three rasters at once, allowing you to compare the results. To illustrate, we’ll create a simple profile using a DEM of a 1:63,360 quadrangle in Alaska.
Installing the Plugin The Profile plugin is installed like all other Python plugins.
This week we highlight the Points to Paths plugin, a handy way to convert a series of points into line features. This plugin lets you “connect the dots” based on an common attribute and a sequence field. The attribute field determines which points should be grouped together into a line. The sequence field determines the order in which the points will connected. The output from this plugin is a shapefile.
QGIS has a lot of plugins, including over 180 that have been contributed by users. If you aren’t using plugins, you are missing out on a lot that QGIS has to offer. I’m starting what I hope to be a regular feature: Plugin of the Week. This week we’ll take a look at Time Manager.
Time Manager lets you browse spatial data that has a temporal component. Essentially this includes anything that changes location through time.
The Plugin Builder allows you to quickly create a skeleton Python plugin by generating all that boring boilerplate that every plugin requires.
Here is a short video showing how to create, compile, and install a new plugin.
For more information, see QGIS Workshop Documentation and the PyQGIS Cookbook.
Writing a QGIS plugin is not overly complicated but represents a bit of work. Using git in conjunction with your development efforts can make sure your investment in coding time is preserved.
Development Tools The QGIS project team has set up a central location for plugin development which includes pretty much everything you need to develop and support your plugins, including:
Issue tracking
Wiki
Documents