Returns a MultiPolygon geometry object which represents a buffered distance around another geometry object.


MI_Buffer ( geometry, dist, unit, calculationType, res )


geometry is an expression which returns a geometry,

dist is a number which represents the distance from the source geometry for the buffer,

unit is an area unit specification,

calculationType is a string that indicates whether to perform a Spherical or Cartesian calculation. There is no default, and

res is a number which specifies the minimum number of segments used in creating a circle from buffering a point.


The geometry object returned is in the same coordinate system as the supplied geometry argument. The distance (dist) is in the units specified by the units argument. If res is NULL or zero, a reasonable default value is used. Otherwise, res must be at least 3. The minimum number of segments used in fractional circles, such as formed when buffering the corners of a rectangle, will be proportionally smaller. (for example, a half circle will have at least res/2 segments). The distance may be either positive or negative.

Valid values for unit are the following distance units:

Value Description
mi miles
km kilometers
in inches
ft feet
yd yards
mm millimeters
cm centimeters
m meters
survey ft US Survey feet
nmi nautical miles
twip twips
pt points
pica picas
degree degrees
li links
ch chains
rd rods