Computes a buffer area around the selected geometries.
The Buffer Operation takes the features from a source vector layer and creates a buffer area of a specified distance around, storing the result on a Result Layer.
If the source layer has features selected, the operation will be performed against them, otherwise, the features from the whole Layer will be used. The Source Layer is not modified by any means. A new Result Layer is created by default, or the user can specify an existing editable vector layer where to store the results.
Go to the Spatial Operations View, and select Buffer from the Operation drop down.
The Buffer Operation’s specific input options will show up.
Now you’re ready to go. Press the Perform button from the View’s tool bar and the operation will begin.
Once you press the Perform button, the operation progress will be shown up on a progress dialog.
The operation may take a while to complete, depending on the amount and complexity of the input geometries.
Once the Operation finishes, if a new Layer were created to hold the result, it will be automatically added to the current Map.
As shown above the newly created Layer (Buffer-1, in green) is added to the map, with one Feature whose Geometry is the aggregated result of applying the specified buffer to the default geometries in the source Features.
The Buffer Operation contains a couple advanced options you can set to control certain aspects of the process.
The setting controls for the Merge Features and Segments per quadrant advanced options.
The Merge Features options controls whether to create a single aggregate geometry for the whole source Features set, or to create a new Feature in the Result Layer per source Feature. By default, this option is checked and a single aggregate Geometry is created. Shown below is the result (Buffer-2 Layer, in red) of applying the same buffer width than the example above, but with the Merge Features option unchecked.
The Segments per quadrant option allows a fine grained control over how many straight segments shall be used to approximate a quarter circle. This is parameter affects how the rounded areas over vertexes are built, as uDig uses linear approximations of curves.
Shown above is the result of operation with * Merge Features unchecked.