Lecture 7: Spatial analysis

Question 1

How is GIS analysis different from mapping or visualization?

Answer 1

`Facilitate geographically distributed analysis of the problem

Question 2

What are the general types of questions that are addressed with GIS?

Answer 2

Location, condition, patterns, trends, implications

Question 3

Choosing an analysis method (procedures/steps)

Answer 3

Database
Mapping
Spatial analysis
Spatial modelling

Question 4

How can spatial relationships be classified?

Answer 4

• into 3 categories
• proximal
• topological
• directional

Question 5

What are the types of pattern?

Answer 5

Random
Uniform
Clustered

Question 6

Do you need cell resolution for perimeter?

Answer 6

Yes, in raster you need cell resolution

Question 7

Do you need cell resolution in area for raster?

Answer 7

Yes, cell resolution is needed

Question 8

What are the measurements in real space (non isotropy effects)

Answer 8

Absolute barrier (Physical features)
Relative barrier (gives various opportunity for passing through space)

Question 9

What is proximity analysis?

Answer 9

Proximity analysis provides a measure of “nearness” or “farness” using distance or some other relative measure of distance such as cost distance or travel time

• conducted to evaluate the influence of objects with respect to other surrounding objects
• Buffers and thiessen polygons are examples

Question 10

Thiessen (voronoi) polygon

Answer 10

Define individual areas of influence around each point in a set
each point in only one polygon is called a proximal region
every point is closer to the point enclosed

Question 11

Vector overlay analysis

Answer 11

AND: INTERSECTION
OR: UNION
NOT : COMPLEMENT
XOR: EXCLUSION

• point in point polygon: containment
  -line - in line polygon: intersection
  polygon-on-polygon: adjacency

Question 12

What are the issues with GIS analysis?

Answer 12

• the choice of zones in the study area influence the output statistics
• the number of zones in the study area influence output statistics

Question 13

What is mean center?

Answer 13

Mean center is one of the many spatial measure to analyze the geographic distribution of data

Question 14

What are potential sources of error in GIS analysis and how can you combat them?

Answer 14

• Data generalization (How to improve: use more accurate instruments)
• Edge and boundary effects (How to improve: Go for a larger area of analysis)
• Resolution effects ( How to improve: Make cell size smaller)