Spatial Projects SQL (spatialSQL)
for MapInfo Professional®

Advanced spatial query and update

  Applications of the Median Line update operator

The median update operator in conjunction with:

	Street Centreline Example The combine operator is used to create casements from cadastral data
	Centrelines are then created automatically from the casements and a nominated search width.
	Catchment Area Example Median Update supports a range of applications including the clipping of catchment areas.
	Maritime boundary generation. There are a number of important provisos detailed in the documentation but a good approximation to economic and territorial boundaries can be produced.
	Arbitrary Selected Objects Create median lines between any selected objects
The median boundary between polygons is derived from the buffered boundary. The edge match between the new boundaries will be exact but the generated boundary nodes will not be recreated at the same location as the original polygon. Attributes attached to the buffered polygons are preserved in the median update version. See a movie of the operation	Buffer - Preserving Original Polygon Boundaries Input polygons with some boundaries touching. MI Pro:Uniform buffer of each object. spatialSQL:  set table 1  query  zero buffer  update  run the update