15.10 - ST_SpheroidalBufferMBR - Teradata Database

Teradata Database SQL Geospatial Types

prodname
Teradata Database
vrm_release
15.10
category
Programming Reference
featnum
B035-1181-151K

Returns an MBR that represents the minimum and maximum latitude and longitude of all points within a given distance from the point. The earth is modeled as a spheroid.

 

Argument …

Specifies …

distance

a FLOAT value for the distance, in meters, from the point to calculate the MBR.

semimajor

an optional FLOAT value for the length, in meters, of the semimajor axis of the spheroid. If omitted, the method uses the WGS84 value of 6,378,137.0 meters.

invflattening

an optional FLOAT value for the inverse flattening of the spheroid. If omitted, the method uses the WGS84 value of 298.257223563.

Returns an MBR that represents the minimum and maximum latitude and longitude of all points within a given distance from the point.

ST_Point

For the MBR calculation, the planet is modeled as a spheroid. If you do not pass in values for the semimajor and invflattening arguments, the computation uses the semimajor axis and the inverse flattening ratio from the World Geodetic System, WGS84. A value of 6,378,137.0 meters is used for the semimajor axis, and a value of 298.257223563 is used for the inverse flattening ratio.

ST_SphericalBufferMBR and ST_SpheroidalBufferMBR basically perform the same function, but with different performance and accuracy. ST_SphericalBufferMBR models the earth as a simple sphere, so it performs better than ST_SpheroidalBufferMBR, but with less accuracy. ST_SpheroidalBufferMBR models the earth as a spheroid, so it returns a more accurate MBR, but it runs slower than ST_SphericalBufferMBR.

The returned MBR cannot cross the longitude value of +/-180 or the latitude value of +/-90. The MBR cannot cover more than 180 degrees of latitude or longitude on the sphere or spheroid.

This example uses ST_SpheroidalBufferMBR to calculate an MBR that is 5000 meters from a point at longitude 100 and latitude 30:

   SELECT 
   NEW ST_Geometry('POINT(100 30)').ST_SpheroidalBufferMBR( 5000.0 );