How is "touch the boundary of" defined in GIS?

In Geographic Information Systems (GIS), "touch the boundary of" is defined specifically as a spatial relationship where two geometries share a common boundary point but do not overlap or intersect in any other way. This means that at least one point of the boundary of one feature touches a point on the boundary of another feature, while the interiors do not intersect at all, thereby making the intersection of geometries empty.

This definition is crucial in understanding spatial relationships in GIS, as it helps in analyzing how different features interact with one another without implying that they share area or extent beyond just a boundary point. The definition aligns with various spatial operations used in GIS software, such as determining adjacency or proximity between different geographic features.

The other options suggest forms of overlap or intersection that do not align with the concept of "touching the boundary." For example, full intersection implies that the two geometries completely overlap each other, which does not fit the definition of touching. Similarly, options about sharing borders extensively or overlapping geometries extensively introduce a level of intersection that contradicts the meaning of merely touching a boundary. Thus, the clear definition in GIS accommodates only those instances where geometries interact at their boundaries without any interior overlap, confirming that the intersection remains empty.