ST_InterpolatePoint — Returns the interpolated measure of a geometry closest to a point.
float8 ST_InterpolatePoint(geometry  linear_geom_with_measure, geometry  point);
Returns an interpolated measure value of a linear measured geometry at the location closest to the given point.
                 
               | 
              |
| 
                 Use this function only for linear geometries with an M component  | 
            
Disponibilità: 2.0.0
            
 Questa funzione supporta il 3d e non distrugge gli z-index. 
SELECT ST_InterpolatePoint('LINESTRING M (0 0 0, 10 0 20)', 'POINT(5 5)');
 ---------------------
         10