Improving the Accuracy and the Efficiency of Geo-Processing through a Combinative Geo

253 Pages·2016·6.87 MB·English

Improving the Accuracy and the Efficiency of
Geo-Processing through a Combinative Geo-
Computation Approach

Zhiwei Cao

Thesis submitted for the Degree of
Doctor of Philosophy (PhD)

Department of Civil, Environmental and Geomatic Engineering
University College London

Janurary, 2016

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Declaration

I, Zhiwei Cao confirm that the work presented in this thesis is my own. Where
information has been derived from other sources, I confirm that this has been indicated
in the thesis.

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Abstract
Geographical Information Systems (GIS) have become widely used for applications
ranging from web mapping services to environmental modelling, as they provide a rich
set of functions to solve different types of spatial problems. In the meantime,
implementing GIS functions in an accurate and efficient manner has received attention,
throughout the development of GIS technologies. This thesis describes the development
and implementation of a novel geo-processing approach, namely Combinative Geo-
processing (CG), which is used to address data processing problems in GIS.
The main purpose of the CG approach is to improve the data quality and efficiency of
processing complex geo-processing models. Inspired by the concept of Map Calculus
(Haklay, 2004), in the CG approach GIS layers are stored as functions and new layers
are created through a combination of existing functions. The functional programming
environment (Scheme programming language) is used in this research to implement the
function-based layers in the CG approach. Furthermore, a set of computation rules is
introduced in the new approach to enhance the performance of the function-based layers,
such as the CG computation priority, which provides a way to improve the overall
computation time of geo-processing.
Three case studies, which involve different sizes of spatial data and different types of
functions are investigated in this research in order to develop and implement the CG
approach. The first case study compares Map Algebra and our approach for
manipulating two different raster layers. The second case study focuses on the
investigation of a combinative function through the implementation of the IDW and
Slope functions. The final case is a study of computational efficiency using a complex
chain processing model.
Through designing the conceptual model of the CG approach and implementing the CG
approach in the number of case studies, it was shown that the new approach provides
many advantages for improving the data quality of geo-processing. Furthermore, the
overall computation time of geo-processing could be reduced by using the CG approach
as it provides a way to use computer resources efficiently and avoid redundant
computations. Last but not least, this thesis identifies a new research direction for GIS
computations and GIS software development, such as how a robust geo-processing tool
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with higher performance (i.e. data quality and efficiency) could be created using the CG
approach.
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Acknowledgements
I would like to take this opportunity to express my gratitude to the people who have
helped and supported me during my PhD study.
First of all, I would like to appreciate my academic supervisor Professor Mordechai
(Muki) Haklay and Professor Tao Cheng for their continuing help, support and guidance.
Without their insights, knowledge and experiences that encouraged me to overcome all
the difficulties, I would never have completed this thesis.
Secondly, I express my sincere and heartfelt thanks to Dr. Artemis Skarlatidou and Dr.
Patrick Weber, who help me to improve my English and academic studies. Thanks are
also extended to all my friends in the UK and oversea, including Dr. Tyng-Rong (Jenny)
Roan, Mr. Alex Rigby, Dr. Jiaqiu Wang, Dr. Shihong Du, their encouragement helps me
overcome various difficulties during my research.
Last but not least, special thanks to my family, including my infant son (Boyuan Cao),
wife (Jingzhe Wei), and parents (Lange Li and Junfeng Cao), for their endless
supporting and understanding.

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Table of Contents
Declaration ........................................................................................................................ 2
Abstract ............................................................................................................................. 3
Acknowledgements ........................................................................................................... 5
Table of Contents .............................................................................................................. 6
List of Figures ................................................................................................................. 13
List of Tables................................................................................................................... 19
List of Acronyms............................................................................................................. 21
1. Introduction ............................................................................................................. 22
1.1 Background....................................................................................................... 22
1.2 Geo-Processing Models ........................................................................................ 23
1.3 Research Motivation ......................................................................................... 25
1.4 Research Aims and Objectives ......................................................................... 28
1.5 The Structure of Thesis .................................................................................... 29
2 Processing GIS Data and Functions ........................................................................ 34
2.1 Introduction ...................................................................................................... 34
2.2 Data Processing In GIS .................................................................................... 35
2.2.1 Data Processing Overview ........................................................................ 36
2.2.2 Spatial Data Processing: Geo-processing.................................................. 38
2.3 Geo-Processing Data Quality ........................................................................... 45
2.3.1 Defining Data Quality Concepts ............................................................... 45
2.3.2 Overview of Data Quality Problems in GIS ............................................. 48
2.3.3 Data Quality Problems of Geo-processing ................................................ 50
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2.3.4 Data Quality Improvement ............................................................................. 56
2.4 Computational Efficiency of Geo-Processing ....................................................... 62
2.4.1 Defining the Computational Efficiency Concept ........................................... 62
2.4.2 Computational Efficiency Problems of Geo-processing ................................ 63
2.4.3 Computational Efficiency Improvement ........................................................ 66
2.5 Conclusion............................................................................................................. 69
3 Conceptual Model of Combinative Geo-processing (CG) Approach ..................... 71
3.1 Introduction ........................................................................................................... 71
3.2 Basic Characteristics of the Combinative Geo-Processing Approach ............. 71
3.2.1 Simple Chain Process ................................................................................ 72
3.2.2 Complex Chain Process ............................................................................ 73
3.3 The Combinative Geo-Processing Conceptual Model ..................................... 75
3.3.1 Input Level ................................................................................................ 76
3.3.2 Processing and Computation ..................................................................... 82
3.3.3 Outputs and Results................................................................................... 84
3.4 Potential Advantages and Disadvantages of the Combinative Geo-Processing
Approach ..................................................................................................................... 85
3.5 Summary........................................................................................................... 86
4 Case Study Design and Combinative Geo-Processing Implementation Methods .. 87
4.1 Introduction ........................................................................................................... 87
4.2 Experimental Design ............................................................................................. 87
4.2.1 Case Study Selection ...................................................................................... 87
4.2.2 Parameter and Function Declaration .............................................................. 92
4.3 Methods Used in Combinative Geo-processing Function Execution ................. 101
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4.3.1 Higher-Order Function ................................................................................. 101
4.3.2 Recursive Algorithms................................................................................... 102
4.3.3 Lazy Evaluation ........................................................................................... 103
4.4 Implementation Tool and Computational Environment ..................................... 105
4.4.1 Programming Paradigms .............................................................................. 105
4.4.2 The Scheme Programming Language .......................................................... 107
4.4.3 Benchmark ................................................................................................... 108
4.4.4 Computational Environment ........................................................................ 119
4.5 Case Study Data Selection .................................................................................. 122
4.6 Chapter Summary................................................................................................ 125
5 Comparing a Raster Overlay Function between Map Algebra and Combinative
Geo-processing .............................................................................................................. 126
5.1 Introduction .................................................................................................... 126
5.2 Case Study 1: ‘Raster Overlay Function Review’ .......................................... 126
5.2.1 Geo-processing Model (Case Study 1) ................................................... 128
5.3 Methodology: ‘Raster Overlay with Raster’ Function Implementations ....... 129
5.3.1 ‘Raster Overlay with Raster’ Function Implementation in The Traditional
Geo-processing Approach: Map Algebra.............................................................. 129
5.3.2 ‘Raster Overlay with Raster’ Function Implementation in The
Combinative Geo-processing Approach ............................................................... 131
5.4 Case study 1: ‘Raster Overlay with Raster’ Function Implementation Datasets
132
5.4.1 Reference data ......................................................................................... 132
5.4.2 Sample Data ............................................................................................ 133
5.5 ‘Raster Overlay with Raster’ Function Implementation Strategy .................. 134
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5.5.1 Single Layers ........................................................................................... 135
5.5.2 Integrated Layers ..................................................................................... 136
5.6 ‘Raster Overlay with Raster’ Function Results .............................................. 138
5.6.1 Single Layers ........................................................................................... 138
5.6.2 Integrated Layers ..................................................................................... 140
5.7 Case Study Results Comparison ..................................................................... 143
5.7.1 Raster Algebra ......................................................................................... 143
5.7.2 Statistical Analysis .................................................................................. 144
5.8 Discussion....................................................................................................... 145
5.9 Summary......................................................................................................... 146
6 Implementing a Simple Chain Processing Using the Combinative Geo-Processing
Function......................................................................................................................... 148
6.1 Introduction .................................................................................................... 148
6.2 Case study 2: Simple Chain Processing Model Review ................................. 148
6.2.1 Slope Function ........................................................................................ 149
6.3 Methodology: The Simple Chain Processing Model Implementations .......... 151
6.3.1 Simple Chain Processing Model Implementation in Traditional Geo-
processing: Sequential Computation ..................................................................... 151
6.3.2 Simple Chain Processing Model Implementation in Combinative Geo-
processing .............................................................................................................. 152
6.4 Case study 2: The Simple Chain Processing Model Dataset .......................... 153
6.5 The Simple Chain Processing Model Implementation Strategy in Case study 2
154
6.6 The Simple Chain Processing Model Results ................................................ 157
6.7 Case study 2: Comparison and Validation of results ..................................... 159
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6.7.1 Monte Carlo Simulation Model .............................................................. 159
6.7.2 Monte Carlo Simulation Results ............................................................. 160
6.8 Discussion....................................................................................................... 163
6.9 Summary......................................................................................................... 165
7 Implementing a Complex Chain Processing Model Using Combinative Geo-
processing Function ...................................................................................................... 167
7.1 Introduction .................................................................................................... 167
7.2 The Implications of Computation Strategy in Geo-processing ...................... 167
7.3 Implementations Combinative Geo-processing Computation Priority .......... 171
7.3.1 Improving GIS Computational efficiency ............................................... 171
7.3.2 Computation Combinative Geo-processing (CG) Computation Priority 172
7.4 Case study 3: The Complex Chain Processing Model Review ...................... 174
7.5 Methodology: The Complex Chain Processing Model Implementations ...... 175
7.5.1 The Complex Chain Processing Model Implementation: ModelBuilder,
ArcGIS 175
7.5.2 The Complex Chain Processing Model Implementation: Combinative
Geo-processing (CG) Approach ............................................................................ 179
7.6 Case study 3: The Complex Chain Processing Model Dataset ...................... 185
7.7 The Complex Chain Processing Model Implementation Strategy in Case study
3 188
7.8 The Complex Chain Processing Model Results ............................................. 189
7.8.1 The Complex Chain Processing Model Results: ModelBuilder ArcGIS 189
7.8.2 The Complex Chain Processing Model Results: The CG Approach using
Computation Priority ............................................................................................. 193
7.9 Case study 3: Comparison of Results ............................................................. 195
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