INTRODUCTION TO SPATIAL ANALYSIS

Four fundamental functions of GIS fall under the manipulation and analysis component (Martin, 1991): 1.Reclassification operations 2.Overlay operations 3.Distance and connectivity measurements 4.Neighbourhood characterisation Will be discussed in the next chapter.

1. Reclassification operations transform the attribute information associated with a single map coverage. E.g. allow the “cause-and-effect” of certain spatial factors be evaluated. E.g. * population densities classified into classes such as 'sparsely populated' or 'overcrowded' etc.) * soil types and farmland values * generalising land use pattern

MAP Example: the darker the more dense the state population

Re-classification Analysis - Association Between Land Value and Soil Types

URBAN RESIDENTIAL URBAN INDUSTRIAL RURAL FOREST RURAL AGRICULTURE URBAN RURAL ORIGINAL CLASSIFICATION GENERALIZED CLASSIFICATION classification provides new patterns/relationships

Classification (cont.) Classification: Land parcels for housing are classed into single storey terrace, double storey terrace and bungalow. Generalisation: single storey terrace, double storey terrace and bungalow are generalised under housing lots

2. Overlay operations involve the combination of two or more maps according to boolean conditions and may result in the delineation of new boundaries of housing market

Ordnance Survey  Crown Copyright. All rights reserved An overlay of three layers of data

3. Distance and connectivity measurements include both simple measures of inter-point distance and more complex operations such as the construction of zones of increasing transport cost away from specified locations. Distance measurement can be used to calculate straight line and network distance. Includes perimeter and area measurements…

MEASUREMENT DISTANCEPARAMETERAREA/SIZE A B C D XY 5 KM A- B = 20 = 40% B- C = 20 = 40% C - D= 10 = 20% 2 10 km

DISTANCE (STRAIGHT LINE) MEASUREMENT A- B: Alor Setar - Kuala Lumpur 360 KM B- C: Kuala Lumpur - Kuantan 270 KM TOTAL: 630 KM

AREA MEASUREMENT

4. Neighbourhood characterisation involves ascribing values to location according to characteristics of the surrounding region. Such operations may involve both summary and mean measures of a variable. This can be used to examine positive and negative spatial autocorrelation house price hedonic models.

Ordnance Survey  Crown Copyright. All rights reserved Neighbourhood analysis of mean selling prices within certain distance of a house

Anselin (1998) proposes that GIS functions can be classified as follows –Selection –Manipulation –Exploration –Confirmation Other View of GIS Functions

GIS functions Selection: involves boolean queries and spatial sampling. This seems similar to the overlay operations function. Manipulation: may be based on attribute data, map data, or integration of both, simultaneously. This means analysing data in an integrated manner where various data as available in the database can be combined in an analysis. Exploration: for investigation of spatial structure and involves description and visualisation. This is relevant to spatial autocorrelation analysis of hedonic models using geo-statistical method Confirmation: for modelling spatial association and/or autocorrelation. This is also more relevant to spatial autocorrelation analysis using geostatistical method.

DATA RECALL can be invoked on spatial and attribute components involves selective search no new objects created examples: * lots owned by foreigners * lots along the substation buffer

LOTS OWNED BY FOREIGNERS

CLASSIFICATION AND GENERALISATION classification - identify a set of characteristics to group together objects. in a vector system, classification involves addition of objects characteristics. in a raster system, classification involves converting or coding cell values. classification examples: Land parcels for housing are classed into single storey terras, double storey terras and bungalow. classification provides new patterns/relationships generalisation: single storey terrace, double storey terrace and bungalow are generalised under housing lots

Housing Age Legend Before to 1999 Map showing classification of buildings according to age

URBAN RESIDENTIAL URBAN INDUSTRIAL RURAL FOREST RURAL AGRICULTURE URBAN RURAL ORIGINAL CLASSIFICATION GENERALIZED CLASSIFICATION

... vector data –converting attribute values for polygon, line and point raster data –converting attribute values of group cell

MEASUREMENT measurement functions includes distance, parameter and area example: land parcels larger than 5 hectares example: shortest distance from KLCC to Pudu bas station

MEASUREMENT DISTANCEPARAMETERAREA/SIZE A B C D XY 5 KM A- B = 20 = 40% B- C = 20 = 40% C - D= 10 = 20% 2 10 km

DISTANCE MEASUREMENT A- B: Alor Setar - Kuala Lumpur 360 KM B- C: Kuala Lumpur - Kuantan 270 KM TOTAL: 630 KM

AREA MEASUREMENT

... MEASUREMENT vector data –area and parameter is obtained from coordinates of the polygon nodes –distance is derived from coordinates of starting/ending nodes –is more accurate than raster data

SEARCHING determine values against target object according to a neighbourhood characteristic three parameters need to be identified –targets –neighbourhood around the targets –applied neighbourhood function for resultant values example: total of households within 1 km of proposed shopping mall –target-shopping mall –neighborhood-in the radius of 1 km –function-total residential units

... SPATIAL SEARCH operated as additional points in polygon, line in polygon and polygon in polygon vector data –point, line or polygon analysed with neighbourhood polygon using coordinate nodes –involves complex calculation with overlapping and out-of-boundary neighbourhood raster data –perform as overlay operations

NEIGHBOURHOOD represents ‘distance’ between map features ‘distance’ unit can be in measurement units or other units like travelling time, noise level, visibility distance etc. requires 4 parameters –target location - schools, highways, etc. –‘distance’ units - meter, dB, ppm, etc. –function for calculation on distance, perimeter, travel time –location to be analysed

... NEIGHBOURHOOD used to generate buffer zones example: a 2km zone along a proposed transmission line alignment; zones exceeds 50dB around the airport neighbourhood is most often complex and involves data from various layers. For example, more than 50dB from noisy roads AND more than 1km from factories AND 15 minutes walking time AND...

R Buffering a Point eg. All area within one mile of a city Buffering a Line eg. All areas within 100 meters of a road Buffering an Area eg. All areas within 500 meters of a wetlands area.

Buffering

OVERLAY Involves two or more data layers Produces new layers Two types of overlay operation –arithmetic overlay –logical overlay Arithmetic overlay involves mathematics operation such as addition, subtraction, multiplication, etc.

MAP ALGEBRA (MULTIPLICATION) OVERLAY BY MULTIPLICATION DISTRICT X CROP AREA 1 BB = OVERLAY BY MAXIMUM VALUE RAINFALL : RAINFALL: RAINFALL: = OVERLAY

... OVERLAY vector data are sometimes more efficient than raster data if data are not dense. –vector data - operation based on the selected data only –raster data - operation on all cells - even null values

Soil Type + Crops Production (ton/ha) Overlay Result GIS Technology: Relationship between Land use and Crop Productivity Overlay Analysis

Jalan Raja Alang Jalan Abdul Aziz Jalan Datuk Malik Jalan Hamzah Jalan Raja Uda Noise Zone Map

Sewerage pond Jalan Raja Alang Jalan Abdul Aziz Jalan Datuk Malik Jalan Hamzah Jalan Raja Uda Area Map For Areas Outside Sewerage Services

Jalan Raja Alang Jalan Abdul Aziz Jalan Hamzah Jalan Raja Uda Pan Malaysian Plastic Jalan Datuk Malik Industrial Buffer Zone Map