Analytics for the Internet of Things (IoT)

Dilation and erosion

With shapely, a positive buffer is a dilation and a negative amount is an erosion. A dilation works as previously described while an erosion shrinks a polygon by the buffer amount. Shapely also has some options for the shape of a cap (the buffer area at the ends of lines) and areas where the buffer joins to itself. The following shows the cap and join style options:

shapely.geometry.CAP_STYLE

Attribute	Value
round	1
flat	2
square	3

 

shapely.geometry.JOIN_STYLE

Attribute	Value
round	1
mitre	2
bevel	3

The following code shows a simple example of how buffering works:

#import linestring class, cap and join stylesfrom shapely.geometry import LineString, CAP_STYLE, JOIN_STYLEunbufferedLine ...