Many of our questions are based on the spatial relationship between two features in the space. For example, what are the bridges that cross the Upper Mississippi River and where are they (spatial relationship between the bridges and the Upper Mississippi River)? What are the properties in Northfield that are in a floodplain (spatial relationship between properties/parcels and floodplains)?
Often, proximity is included in the question. For example, where are the schools 1-mile from a liquor store (spatial relationship between schools and the area 1-mile from liquor stores)?
This lecture note is only about spatial relationships.
In geospatial analysis (and other disciplines), the key words used to describe the various spatial relationships are standardized to build a common ground for all the users and software. The word “cross”, for example, means the same spatial relationship among users so the query “if feature A crosses feature B” returns the same result by all software.
As a GIS user, you need to understand how the various spatial relationships are defined and the key words used to describe them. This helps you use spatial relationships in data query.
GIS software may use human friendly sentences to describe the spatial relationship key words. GIS software may also include the spatial relationships not listed in the slide included with this lecture note (listed at the end of the note). The graphic below shows the spatial relationships available in the ArcGIS Pro “Select by Location” window. You should familiar yourself with the definitions of the spatial relationships implemented in the software you use. For Pro, here is a documentation for version 2.8.
Spatial relationships available in ArcGIS Pro data query “Select by Location”.
As background information for the contents in the slide, the Dimensionally Extended 9-Intersection Model (DE-9IM) is a mathematical approach that defines the spatial relationships between geometries. It dimensionally extends the 9 Intersection Model. DE-9IM expresses spatial relationships as pair-wise intersections of interior, boundary, and exterior of the geometries with consideration for the dimension of the resulting intersections.
Here is the slide introducing eight of the spatial relationships .
