### Buffer

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The Buffer spatial operation generates buffer zones (or zones of influence) around the geometry of objects of a layer, considering a predefined distance. The figure bellow shows examples of buffer zones around a river or an municipality.

If the geometry of the objects are polygons it is possible to ask for internal and/or external buffers, as showed bellow.

Inside and outside buffer | Only outside buffer | Only inside buffer

It is possible to ask for several levels of buffers. Selecting a distance d and n levels will result in n buffers each at a distance d*(n-1). The next figure shows an example of buffers at multiple levels.

As the buffers around different objects might overlap, it is possible to request the dissolving of the boundaries inside the overlapping areas. This is illustrated in the next figure.

It is accessed through:

Vector Processing > Buffer...

1. Select the Input layer to apply the buffer operation. Optionally use Filter with part of the layer name to filter the input layers displayed.
2. Select Fixed at and inform a buffer distance that will be applied to all objects. This value must be in the same SRS unit of the input layer.
3. In the division Rule for polygons, select of of them.
4. In the division Boundaries between buffers, select if overlapping buffers should be dissolved (default behavior) or not.
5. In the division Multiple levels, select the Number of Levels (default 1).
6. Inform the Output Repository by clicking on:

1. to select the output directory and also inform the new layer name to store the result, or
2. to select the Data Source and

- Inform the new Layer Name to store the aggregation result.

7. Click OK to perform the operation or Cancel to close the interface.

### Usage tips

The buffer result can be stored in different TerraLib data sources. Check data source selector for more details on how to select a data source.

The option to use buffer distance for each object based on one of its attributes is under development.