12.16.9.1 Spatial Relation Functions That Use Object Shapes (original) (raw)

12.16.9.1 Spatial Relation Functions That Use Object Shapes

The OpenGIS specification defines the following functions to test the relationship between two geometry values_g1_ and g2, using precise object shapes. The return values 1 and 0 indicate true and false, respectively, except forST_Distance() andDistance(), which return distance values.

These functions support all argument type combinations except those that are inapplicable according to the Open Geospatial Consortium specification.

• Crosses(g1,g2)
  ST_Crosses() andCrosses() are synonyms. For more information, see the description ofST_Crosses().
  Crosses() is deprecated; expect it to be removed in a future MySQL release. UseST_Crosses() instead.
• Distance(g1,g2)
  ST_Distance() andDistance() are synonyms. For more information, see the description ofST_Distance().
  Distance() is deprecated; expect it to be removed in a future MySQL release. Use ST_Distance() instead.
• ST_Contains(g1,g2)
  Returns 1 or 0 to indicate whether_g1_ completely contains_g2_. This tests the opposite relationship as ST_Within().
• ST_Crosses(g1,g2)
  The term spatially crosses denotes a spatial relation between two given geometries that has the following properties:
  • The two geometries intersect.
  • Their intersection results in a geometry that has a dimension that is one less than the maximum dimension of the two given geometries.
  • Their intersection is not equal to either of the two given geometries.
    This function returns 1 or 0 to indicate whether_g1_ spatially crosses_g2. Ifg1_ is aPolygon or aMultiPolygon, or if_g2_ is a Point or a MultiPoint, the return value isNULL.
    This function returns 0 if called with an inapplicable geometry argument type combination. For example, it returns 0 if the first argument is a Polygon orMultiPolygon and/or the second argument is a Point orMultiPoint.
    Returns 1 if g1 spatially crosses_g2. ReturnsNULL if g1 is a Polygon or aMultiPolygon, or ifg2_ is a Point or a MultiPoint. Otherwise, returns 0.
    This function returns 0 if called with an inapplicable geometry argument type combination. For example, it returns 0 if the first argument is a Polygon orMultiPolygon and/or the second argument is a Point orMultiPoint.
    ST_Crosses() andCrosses() are synonyms.
• ST_Disjoint(g1,g2)
  Returns 1 or 0 to indicate whether_g1_ is spatially disjoint from (does not intersect) g2.
• ST_Distance(g1,g2)
  Returns the distance between g1 and g2. If either argument isNULL or an empty geometry, the return value is NULL.
  This function processes geometry collections by returning the shortest distance among all combinations of the components of the two geometry arguments.
  If an intermediate or final result produces NaN or a negative number, anER_GIS_INVALID_DATA error occurs.

mysql> SET @g1 = Point(1,1);  
mysql> SET @g2 = Point(2,2);  
mysql> SELECT ST_Distance(@g1, @g2);  
+-----------------------+  
| ST_Distance(@g1, @g2) |  
+-----------------------+  
|    1.4142135623730951 |  
+-----------------------+  

ST_Distance() andDistance() are synonyms.

• ST_Equals(g1,g2)
  Returns 1 or 0 to indicate whether_g1_ is spatially equal to_g2_.

mysql> SET @g1 = Point(1,1), @g2 = Point(2,2);  
mysql> SELECT ST_Equals(@g1, @g1), ST_Equals(@g1, @g2);  
+---------------------+---------------------+  
| ST_Equals(@g1, @g1) | ST_Equals(@g1, @g2) |  
+---------------------+---------------------+  
|                   1 |                   0 |  
+---------------------+---------------------+  

• ST_Intersects(g1,g2)
  Returns 1 or 0 to indicate whether_g1_ spatially intersects_g2_.
• ST_Overlaps(g1,g2)
  Two geometries spatially overlap if they intersect and their intersection results in a geometry of the same dimension but not equal to either of the given geometries.
  This function returns 1 or 0 to indicate whether_g1_ spatially overlaps_g2_.
  This function returns 0 if called with an inapplicable geometry argument type combination. For example, it returns 0 if called with geometries of different dimensions or any argument is a Point.
• ST_Touches(g1,g2)
  Two geometries spatially touch if their interiors do not intersect, but the boundary of one of the geometries intersects either the boundary or the interior of the other.
  This function returns 1 or 0 to indicate whether_g1_ spatially touches_g2_.
  This function returns 0 if called with an inapplicable geometry argument type combination. For example, it returns 0 if either of the arguments is a Point or MultiPoint.
  ST_Touches() andTouches() are synonyms.
• ST_Within(g1,g2)
  Returns 1 or 0 to indicate whether_g1_ is spatially within_g2_. This tests the opposite relationship asST_Contains().
• Touches(g1,g2)
  ST_Touches() andTouches() are synonyms. For more information, see the description ofST_Touches().
  Touches() is deprecated; expect it to be removed in a future MySQL release. UseST_Touches() instead.