{ "name": "point_on_surface", "type": "function", "groups": ["GeometryGroup"], "description": "Returns a point guaranteed to lie on the surface of a geometry.", "arguments": [{ "arg": "geometry", "description": "a geometry" }], "examples": [{ "expression": "point_on_surface(@geometry)", "returns": "a point geometry" }], "tags": ["point", "surface", "lie", "centroid", "overlay", "within"] }