ST_MakeEmptyCoverage
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## Name

ST_MakeEmptyCoverage — Cover georeferenced area with a grid of empty raster tiles.

## Synopsis

`raster ST_MakeEmptyCoverage(`integer tilewidth, integer tileheight, integer width, integer height, double precision upperleftx, double precision upperlefty, double precision scalex, double precision scaley, double precision skewx, double precision skewy, integer srid=unknown`)`;

## Description

Create a set of raster tiles with ST_MakeEmptyRaster. Grid dimension is `width` & `height`. Tile dimension is `tilewidth` & `tileheight`. The covered georeferenced area is from upper left corner (`upperleftx`, `upperlefty`) to lower right corner (`upperleftx` + `width` * `scalex`, `upperlefty` + `height` * `scaley`).

Note that scaley is generally negative for rasters and scalex is generally positive. So lower right corner will have a lower y value and higher x value than the upper left corner.

Availability: 2.4.0

## Examples Basic

Create 16 tiles in a 4x4 grid to cover the WGS84 area from upper left corner (22, 77) to lower right corner (55, 33).

    SELECT (ST_MetaData(tile)).* FROM ST_MakeEmptyCoverage(1, 1, 4, 4, 22, 33, (55 - 22)/(4)::float, (33 - 77)/(4)::float, 0., 0., 4326) tile;

     upperleftx | upperlefty | width | height | scalex | scaley | skewx | skewy | srid | numbands
    -------------------------------------------------------------------------------------
             22 |         33 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          30.25 |         33 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
           38.5 |         33 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          46.75 |         33 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
             22 |         22 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          30.25 |         22 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
           38.5 |         22 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          46.75 |         22 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
             22 |         11 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          30.25 |         11 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
           38.5 |         11 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          46.75 |         11 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
             22 |          0 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          30.25 |          0 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
           38.5 |          0 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0
          46.75 |          0 |     1 |      1 |   8.25 |    -11 |     0 |     0 | 4326 |        0

## See Also

ST_MakeEmptyRaster

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