1. Basic Spatial Analysis Tools
Spatial Data Models
1/3/2019
Basic Spatial Analysis Tools
Queries
Spatial Joins
Map Overlays
Buffers
© J.M. Piwowar
Basic Spatial Analysis Tools
© J.M. Piwowar

2. Queries Attribute Queries Spatial Queries
Select spatial features based on attribute information.
e.g. Find all the Canadian cities with over 1 million inhabitants.
Spatial Queries
Select spatial features based on their location relationships.
e.g. Find all the Canadian cities within 100 km of the U.S. border.
© J.M. Piwowar
Basic Spatial Analysis Tools

3. Spatial Queries Spatial queries in ArcGIS: intersect …
are within a distance of …
completely contain …
are completely within …
have their centre in …
share a line segment with …
touch the boundary of …
are identical to …
are crossed by the outline of …
contain …
are contained by …
© J.M. Piwowar
Basic Spatial Analysis Tools

4. Spatial Joins
Joins spatial features based on their relative locations.
Attributes from the source layer are processed and added to the destination layer.
© J.M. Piwowar
Basic Spatial Analysis Tools

5. Spatial Joins Simple Joins
Spatial Data Models
1/3/2019
Spatial Joins
Simple Joins
An object in the source layer corresponds to one (or more) objects in the destination layer.
All the attributes from the source layer are appended to the destination layer.
e.g. To help understand the incidence of crime in a city, we might join the crime locations (points) to neighbourhoods (areas).
Used for a one-to-one or one-to-many relationship.
© J.M. Piwowar
Basic Spatial Analysis Tools
© J.M. Piwowar

6. Spatial Joins Distance Joins
Spatial Data Models
1/3/2019
Spatial Joins
Distance Joins
Identifies the closest object in the source layer to selected object(s) in the destination layer.
All the attributes from the closest object, plus a distance field to show how close they are, are transferred to the selected object(s) in the destination layer.
e.g. Join the nearest prairie dog town to the Frenchman River.
Used for a many-to-one or many-to-many relationship.
Davis, B.E., GIS: A Visual Approach (2nd ed.). Albany, NY: OnWord Press.
© J.M. Piwowar
Basic Spatial Analysis Tools
© J.M. Piwowar

7. Spatial Joins Summarized Joins
Spatial Data Models
1/3/2019
Spatial Joins
Summarized Joins
Identifies the closest object(s) in the source layer to selected object(s) in the destination layer.
The numeric attributes from the closest object(s) are summarized and transferred to the selected object(s) in the destination layer.
maximum, minimum, mean, standard deviation, average, etc.
e.g. What is the average population of the prairie dog towns within 1 km of the Frenchman River?
Used for a many-to-one or many-to-many relationship.
Davis, B.E., GIS: A Visual Approach (2nd ed.). Albany, NY: OnWord Press.
© J.M. Piwowar
Basic Spatial Analysis Tools
© J.M. Piwowar

8. Map Overlays
Combines spatially coincident features from different layers to create new features.
Chrisman, Exploring Geographic Information Systems. New York : Wiley.
© J.M. Piwowar
Basic Spatial Analysis Tools

9. Map Overlay Union Overlay
A resort is interested in buying new forest areas to extend the scenic forest drive. "Where are the forest areas OR areas within the resort?"
Heywood et al., An Introduction to Geographical Information Systems. Prentice Hall
© J.M. Piwowar
Basic Spatial Analysis Tools

10. Map Overlay Intersect Overlay
Where are the areas of forest within the resort area?
Heywood et al., An Introduction to Geographical Information Systems. Prentice Hall
© J.M. Piwowar
Basic Spatial Analysis Tools

11. Map Overlay Clip Overlay
What is the percentage of the resort area covered by forest? You need to first trim the forest cover to the polygon of the resort.
Heywood et al., An Introduction to Geographical Information Systems. Prentice Hall
© J.M. Piwowar
Basic Spatial Analysis Tools

12. Map Overlay ArcGIS Help: Overlay analysis © J.M. Piwowar
Basic Spatial Analysis Tools

13. Buffers
Creates areas by extending outward (or inward) a specified distance from point, line, or polygon features.
Davis, B.E., GIS: A Visual Approach (2nd ed.). Albany, NY: OnWord Press.
© J.M. Piwowar
Basic Spatial Analysis Tools

14. Buffers ArcGIS Help: Buffer (Analysis) © J.M. Piwowar
Basic Spatial Analysis Tools