ST_Touches
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## Name

ST_Touches — Return true if raster rastA and rastB have at least one point in common but their interiors do not intersect.

## Synopsis

`boolean ST_Touches(` raster rastA , integer nbandA , raster rastB , integer nbandB `)`;

`boolean ST_Touches(` raster rastA , raster rastB `)`;

## Description

Return true if raster rastA spatially touches raster rastB. This means that rastA and rastB have at least one point in common but their interiors do not intersect. If the band number is not provided (or set to NULL), only the convex hull of the raster is considered in the test. If the band number is provided, only those pixels with value (not NODATA) are considered in the test.

This function will make use of any indexes that may be available on the rasters.

To test the spatial relationship of a raster and a geometry, use ST_Polygon on the raster, e.g. ST_Touches(ST_Polygon(raster), geometry).

Availability: 2.1.0

## Examples

    SELECT r1.rid, r2.rid, ST_Touches(r1.rast, 1, r2.rast, 1) FROM dummy_rast r1 CROSS JOIN dummy_rast r2 WHERE r1.rid = 2;

     rid | rid | st_touches
    -----+-----+------------
       2 |   1 | f
       2 |   2 | f

## See Also

ST_Intersects

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