vec:BufferFeatureCollection process takes a feature collection and applies a buffer to each feature. The buffer distance can be a fixed value for all features, a variable value, with the values taken from an attribute in the feature collection, or it could be a combination of the two.
The resulting feature collection will always contain polygons regardless of the input.
The attribute names and values of the output feature collection will match those of the input.
Inputs and outputs¶
||Input feature collection||SimpleFeatureCollection||Required|
||Fixed value buffer distance||Double||Required|
||Attribute containing a variable buffer distance value||String||Required|
- The buffer distance is assumed to be in the units of the input feature collection.
- The buffer distance is also assumed to be a Cartesian distance, so unexpected output may occur with data in geographic coordinates.
- If you want to use the
attributeNameparameter to specify a buffer distance, set the required
- Negative buffer distance values may be used for input polygons. This will result in output features being reduced by the buffer distance instead of expanded.
Fire station coverage¶
Assuming that a fire station has an effective response radius of about 3 km, buffering the
medford:firestations layer will determine the areas that may be covered by existing fire stations.
As the input feature collection uses geographic coordinates (EPSG:4326), the distance must be converted to degrees. As the location of these features is approximately 42 degrees N, 3 km can be approximated as 0.024 degrees.
The resulting feature collection looks like this: