Description
Returns a MultiPolygon geometry object which represents a buffered distance around another geometry object.
Syntax
MI_Buffer ( geometry, dist, unit, calculationType, res )
Arguments
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.
Remarks
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 |