
Geometric Planar Properties of
Basic MapInfo Objects as Used Within spatialSQL
spatialSQL
refers to properties of objects such as end, edge, node. This table lists
these properties. Whilst the edge of a point object is meaningless,
this definition indicates whether the attribute exists for the purposes of the
described spatial operation.
Underline indicates MapInfo defined or used property.

Object

Object Type


Property

Symbol

Line

Polyline

Polygon


Object
Components






Node





Intrinsic 
End





Properties 
Edge






Boundary






Interior






Rotation






MBR






Direction






Geometric
Centroid





Derived 
Shifted
MBR
Centroid





Properties 
Visual Centroid






Principal
Axes






Side

All





Aspect

All




Applied
Properties 
Style

symbol
style

line
style

line
style

region
style



For a polyline aspect and side are determined
at the segment containing the centroid.

Node means any node defined for an object.

For a polygon, end is any single node on the
boundary. Whilst a polygon has a defined start node, its definition is
arbitrary, likely to change with basic manipulation and thus of dubious value.

An edge match includes the nodes defining that edge.

The centroid of a region may be outside the region boundary. (eg.
Ushape)

A point object has all sides and aspects.

A region object has no sides or aspect definition.

The end segments of linear objects may be considered as extending
to the limit of data bounds for the purposes of side and aspect.
The actual extent is usually determined by a buffering method.

Style attributes are only mentioned here because they can
change the apparent (visual) properties of objects. (eg. hide the boundary of a
polygon).

Object collection properties are a superset of object properties.
eg. A multisection polyline will contain multiple pairs of ends. A region is a
collection of polygons.

Principal Axes:
Ixx is the moment of inertia (2nd moment of area) about the xaxis
Iyy is the moment about Y
Ixy is the product of inertia
I1,I2 are principal moments of inertia.
Theta is the angle of the principal axes to the X axis.


Spatial Relationships
The SQL method compares object pairs in the following manner:
Spatial Operator

Description

As
defined
by

Intersects

The boundary or interior of the objects intersect

MapInfo

Within

The centroid of the first object is within the boundary
of the second object

MapInfo

Entirely within 
The boundary of the first object is entirely within the boundary of
the second object. 
MapInfo

Contains

The boundary of the first object contains the centroid
of the second object

MapInfo

Contains entire

The boundary of the first object contains the boundary
of the second object

MapInfo

Touch

A node on one object intersects the boundary of the
second object

spatialSQL

Touch Ends 
One or both ends of the objects touch. Regions touch at a single
node 
spatialSQL

Touch Edge 
One or more edges of the objects touch along the full length of one
edge. 
spatialSQL

Disjoint

Boundary and interior of the objects dont intersect 
spatialSQL

Equals Scalar 
The boundary of the objects have identical geometry but
in either node order. 
spatialSQL

Equals

The boundary of the objects have identical geometry and
the direction of the objects are identical.

spatialSQL

