SDO_UTIL.GET_TILE

Format

SDO_UTIL.GET_TILE_ENVELOPE(
    tile_x     IN NUMBER,
    tile_y     IN NUMBER,
    tile_zoom  IN NUMBER,
    google_ts  IN BOOLEAN DEFAULT TRUE
) RETURN MDSYS.SDO_GEOMETRY;

Description

Converts a tile address into a tile envelope (an SDO geometry describing a square).

Parameters

tile_x

The X ordinate of the origin point of the tile being fetched.

The minimum valid value for this parameter is zero. The maximum valid value is dependent on the zoom specified and can be computed as max(X) = (2^tile_zoom) - 1. Note that specifying a X ordinate outside the valid range raises an exception.

tile_y

The Y ordinate (in NUMBER format) of the origin point of the tile being fetched.

The minimum valid value for this paramter is zero. The maximum valid value is dependent on the zoom specified and can be computed as max(Y) = (2^tile_zoom) - 1. Note that specifying a Y ordinate outside the valid range raises an exception.

tile_zoom

Determines the number of tiles required to divide a map. These segments can then be joined at a higher resolution without having to read in the entire map.

For instance, a tile_zoom of zero is a single tile of the entire map without a lot of details. A tile_zoom of n breaks the map into 2^n x 2^n tiles (that is, the number of tiles along the X axis times the number of tiles along the Y axis). For example, at a tile_zoom of 8 there would be 65,536 tiles. This implies that higher the value of n, the more details there are in a tile. Note that the parameter values outside the valid range raise an exception.

google_ts

Boolean value that indicates if the Google tiling scheme is used.

The following two tiling schemes are supported when reading the tile addresses:

GOOGLE: In this tiling scheme, the origin point (X,Y) of a tile is in the northwest corner. The X ordinates increase as tiles are read from west to east. The Y ordinates increase as tiles are read north to south.
TMS: In this tiling scheme, the origin point (X,Y) of a tile is in the southwest corner. The X ordinates still increase as tiles are read from west to east, but the Y ordinates increase as tiles are read from south to north.

Usage Notes

None.

Example

The following example converts the tile coordinates into an SDO_GEOMETRY using the default Google tiling scheme.

SELECT SDO_UTIL.GET_TILE_ENVELOPE(131, 84, 8) FROM DUAL;

SDO_UTIL.GET_TILE_ENVELOPE(131,84,8)(SDO_GTYPE, SDO_SRID, SDO_POINT(X, Y, Z), SDO_ELEM_INFO, SDO_ORDINATES)
-----------------------------------------------------------------------------------------------------------
SDO_GEOMETRY(2003, 3857, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 3), SDO_ORDINATE_ARRAY(465715.526, 6727436.88, 630085.712, 6891807.07))

The following example converts the tile coordinates into an SDO_GEOMETRY using the TMS tiling scheme.

SELECT SDO_UTIL.GET_TILE_ENVELOPE(131, 171, 8) FROM DUAL;

SDO_UTIL.GET_TILE_ENVELOPE(131,171,8,FALSE)(SDO_GTYPE, SDO_SRID, SDO_POINT(X, Y, Z), SDO_ELEM_INFO, SDO_ORDINATES)
------------------------------------------------------------------------------------------------------------------
SDO_GEOMETRY(2003, 3857, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 3), SDO_ORDINATE_ARRAY(465715.526, -6891807.1, 630085.712, -6727436.9))