1. Analytical GIS Capabilities
There are many ways to classify the analytic functions of a GIS. The classification used for this lecture makes the following distinctions in function classes:
Measurement and classification functions
Overlay functions
Neighbourhood functions
Connectivity functions

2. Spatial selection queries
Spatial selection by attribute conditions

3. Classification Line Dissolve (Map Dissolve) 2 3 1 2 1 4
1 grain crops 2 orchards residential 4 commercial
1 agricultural non-agricultural

4. Overlay Functions These functions (Operators) are as follows:
polygon intersection
spatial join
polygon clipping
polygon overwrite

5. Overlay A series of registered data layers ‘overlaying’ each other
Arguably the most important GIS analysis function

6. Overlay
An overlay operation takes two or more data layers as input and results in an output data layer
Three types of overlay:
Point in polygon
Line in polygon
Polygon (polygon on polygon)

7. Point in Polygon Overlay
Trees
Land Cover
NewTrees 1 2 A A C + = C B B
Point Table
Poly Table
Point Table
ID Tree
A Elm B Maple C Elm
ID Cover
Rural Urban
ID Tree Cover
A Elm Rural B Maple Rural C Elm Urban

8. Line in Polygon Overlay
Streets
Land Cover
NewStreets C C A A + = D B B 1 2
Line Table
Poly Table
Line Table
ID Street
A Race B Race C Arch
ID Cover
Rural Urban
ID Street Cover
A Race Rural B Race Urban C Arch Urban D Race Urban

9. Polygon Overlay
Intersection (and)
Union (or)
Identity

10. Polygon Overlay: Intersection
Agriculture
Land Cover
<Intermediate> A A B B
ID Owner
A Brown B Smith
ID Cover
A commercial B industrial
Area of intersection
New node

11. Polygon Overlay: Intersection
<Intermediate>
Output A B
ID Owner Cover
A Brown commercial
B Smith industrial
Area of intersection
New node

12. Polygon Overlay: Union
Agriculture
Land Cover
<Intermediate> A A B B
ID Owner
A Brown B Smith
ID Cover
A commercial B industrial
Area of union
New node

13. Polygon Overlay: Union
Output
<Intermediate> B C A D E
ID Owner Cover
A commercial B Brown commercial C Brown D Smith E Smith industrial
Area of union
New node

14. Polygon Overlay: Identity
Agriculture (input layer)
Land Cover (identity layer)
<Intermediate> A A B B
ID Owner
A Brown B Smith
ID Cover
A commercial B industrial
Area of identity
New node

15. Polygon Overlay: Identity
Output
<Intermediate> A B C D
ID Owner Cover
A Brown commercial B Brown C Smith D Smith industrial
Area of identity
New node

16. Raster Overlay
GISs that support raster processing - as do most -usually have a full language to express operations on rasters.

17. Neighborhood functions
To perform neighborhood analysis, we must:
state which target locations are of interest to us, and what is their spatial extent,
define how to determine the neighborhood for each target,
define which characteristic(s) must be computed for each neighborhood.

18. Neighbourhood functions
Proximity computation:
Buffer zone generation
Thiessen polygon generation

19. Neighbourhood functions

20. Buffer Definition of what is within/without a given proximity
Line buffer
Point buffer
Polygon buffer

21. Doughnut Buffer e.g. within 10 meters but not within 5 meters
Buffer polygon 5 10
‘Hole’

22. Variable Buffer
Buffer distance varies by some feature attribute or friction surface

23. Variable Buffer ID Dist A 3 B 2 C 5 B A Original line C 4 6 10
Buffer polygon

25. Neighbourhood functions

26. Unit Demand (l/day/ha)
Table 12.3 Computing water use based on land-use area 
Node
Total Node Area (ha)
Land Use Type
Land Use Area (ha)
Unit Demand (l/day/ha)
Demand (l/day)
Node Total (l/day)
J-1
6.88
Industrial
11,200
77,100
J-2
7.69
Industrial Commercial Residential
11,200 4,700 7,500
15,500 4,300 40,400
60,200
J-3
Commercial Residential Undeveloped
4,700 7,500 0
6,100 38,600 0
44,800
J-4
8.50
Industrial Commercial Residential Undeveloped
11,200 4,700 7,500 0
1, ,400 0
20,800
J-5
8.09
Industrial Commercial
11,200 4,700
72,500 7,600
80,100
J-6
4.86
2,200 6,400 24,800
33,400