In GIS, the positive (or negative) buffer of a geometry is defined as the Minkowski sum (or difference) of the geometry with a circle of radius equal to the absolute value of the buffer distance. In the CAD/CAM world buffers are known as offset curves. In morphological analysis the operation of positive and negative buffering is referred to as erosion and dilation
The buffer operation always returns a polygonal result. The negative or zero-distance buffer of lines and points is always an empty Polygon.
Since true buffer curves may contain circular arcs, computed buffer polygons are only approximations to the true geometry. The user can control the accuracy of the approximation by specifying the number of linear segments used to approximate arcs. This is specified via BufferParameters.setQuadrantSegments(int) or setQuadrantSegments(int).
The end cap style of a linear buffer may be specified . The following end cap styles are supported:
The join style of the corners in a buffer may be specified . The following join styles are supported:
The buffer algorithm can perform simplification on the input to increase performance. The simplification is performed a way that always increases the buffer area (so that the simplified input covers the original input). The degree of simplification can be specified , with a default used otherwise. Note that if the buffer distance is zero then so is the computed simplify tolerance, no matter what the simplify factor.