Welcome to Multi-Distance Buffer’s documentation!

Contents:

Functionality

The Multi-Distance Buffer plugin creates a multi-distance / multi-zone buffer vector dataset from an input vector layer and a set of distances. The result polygon dataset consists of bands (donut type) of regions according to the buffer distances provided. If 100 and 200 are provided as distances, the result dataset will consist of two bands - one will contain all areas that are within 100 units from the geometries of the input vector layer (including the geometry itself), the other will contain all areas that are from 100 to 200 units from the geometries of the input vector layer. Negative buffer distances are allowed for polygon layers. Buffer distances can be added and deleted. The keyboard can be used to add the buffer distances quickly (number followed by <enter>).

The user can choose to only buffer around selected features. If the user selects a layer with a selection, the default will be set to use only selected features. If there is no selection in the chosen layer, the default will be set to not using selected features only. The user can then modify this using a checkbox.

Implementation

Buffers for all the distances are created using the buffer function of QgsGeometryAnalyzer. This buffer function does not support memory layers as output, so a temporary Shapefile format dataset is created for each buffer distance. This buffer function does not support the specification of buffer accuracy (segments / arc vertex distance / maximum deviation), so this is not available to the user.

The buffers are combined using the symDifference function of QgsGeometry.

Indices and tables

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