Mastering geospatial development with QGIS 3. x : an in-depth guide to becoming proficient in spatial data analysis using QGIS 3.4 and 3.6 with Python

453 Pages·2019·34.902 MB·English

by  Shammunul Islam

Mastering Geospatial
Development with QGIS 3.x
Third Edition
An in-depth guide to becoming proficient in spatial data
analysis using QGIS 3.4 and 3.6 with Python
Shammunul Islam
Simon Miles
Kurt Menke, GISP
Richard Smith Jr., GISP
Luigi Pirelli
John Van Hoesen, GISP
BIRMINGHAM - MUMBAI
Mastering Geospatial Development
with QGIS 3.x
Third Edition
Copyright © 2019 Packt Publishing
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First published: March 2015
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Third edition: March 2019
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Contributors
About the authors
Shammunul Islam is a consulting spatial data scientist at the Institute of Remote Sensing,
Jahangirnagar University, and a senior consultant at ERI, Bangladesh. He develops
applications for automating geospatial and statistical analysis in different domains such as
in the fields of the environment, climate, and socio-economy. He also consults as a survey
statistician and provides corporate training on data science to businesses. Shammunul
holds an MA in Climate and Society from Columbia University, an MA in development
studies, and a BSc in statistics.
Simon Miles is a GIS/web developer working for the Royal Borough of Windsor and
Maidenhead, and has been working in the GIS industry since 2003. Both in the office and at
home, he works using open source technologies. His main kit or stack includes QGIS,
PostGIS, Python, GDAL, Leaflet, JavaScript, and PHP. His main focus presently is on digital
delivery/transformation, chiefly through the consolidation of data, applications, and legacy
systems, and replacing these with APIs and web applications. In 2013, Simon helped to
establish the UK QGIS user group, which holds regional meetings two or three times a year.
Kurt Menke, GISP, a former Albuquerque, New Mexico, USA-based archaeologist, has an
MS in geography from the University of New Mexico in 2000. He has founded Bird's Eye
View to apply his expertise with GIS technology toward ecological conservation. His other
focus areas are public health and education. He is an avid GIS proponent since he began
writing MapServer applications in 2002. He has authored Discover QGIS. In 2015, Kurt was
voted in as an OSGeo Charter Member. He is a FOSS4G educator and a co-author of the
GeoAcademy. In 2015, he was awarded the Global Educator of the Year Team Award by
GeoForAll as part of the GeoAcademy team. He authors an award-winning blog on
FOSS4G technologies and their use in community health mapping.
Richard Smith Jr., GISP, is an assistant professor of geographic information science in the
School of Engineering and Computing Sciences at Texas A&M University – Corpus Christi.
He has a Ph.D. in geography from the University of Georgia and holds an MSc in computer
science and a BSc in geographic information science from Texas A&M University-Corpus
Christi. Richard actively researches in cartography, systems integration, and the use of
geospatial technology for disaster response. He is an advocate for FOSS4G and building a
FOSS4G curriculum. He is also one of the co-authors of the FOSS4G Academy.
Luigi Pirelli is a QGIS core developer and software analyst with a degree in computer
science from Bari University. He worked for 15 years in the Satellite Ground Segment and
Direct Ingestion for the European Space Agency. He is also involved in GFOSS world,
contributing in QGIS, GRASS, & MapServer core, and developing and maintaining many
QGIS plugins. Luigi is the founder of the OSGEO Italian local GFOSS chapter. He has
taught PyQGIS, delivering training from basic to advanced levels, and supporting
companies to develop their own specific QGIS plugins. He founded a local hackerspace
group. Bricolabs.cc. He likes training groups on conflict resolution. Other than this book, he
has also contributed to the Lonely Planet guide Cycling Italy.
John Van Hoesen, GISP, is an associate professor of geology and environmental studies at
Green Mountain College in rural west-central Vermont, USA. He earned an MS and a Ph.D.
in geology from the University of Nevada, Las Vegas, in 2000 and 2003. He is a certified
GISP with a broad background in the geosciences and has used some flavor of GIS to
evaluate and explore geological processes and environmental issues since 1997. John has
used and taught graduate, undergraduate, and continuing education courses using some
variants of FOSS GIS since 2003.
About the reviewers
Giuseppe De Marco, a Ferentino based agricultural engineer, has a Bachelor's in
agriculture from the University of Pisa. He started programming at an early age. He
developed deep interests in geography and GIS during his bachelor’s. He then got
introduced to GRASS and QGIS while working with Eris commercial products. Since QGIS
1.7.4, he has been developing plugins for it, In 2008, he partnered with his 2 colleagues and
started Pienocampo (open field), a website that hosts plugins made by him which are also
hosted on OGIS official repository. He likes studying geography, surveying, tree risk
assessment, landscaping, bioengineering, and farm consulting. He also likes imparting
knowledge on how to use QGIs and other open source software.
Chima Obi is the lead geospatial analyst at AGERPoint Inc. He has over 4 years of
experience as a geospatial analyst. His specialty includes processing LIDAR data and
feature extraction from raster/imagery data utilizing Python and R programing, as well as
exploring other open source geospatial tools. He got his Bachelors in soil science from
the Federal University of Technology, Owerri, Nigeria in 2010. He moved to the United
States where he obtained his master’s degree in environmental science and got a
certification in Geospatial information systems in 2016.
Prior to working at AGERPoint, he worked as a geospatial analyst at West Virginia District
of Highways in 2015 and 2016.
I would like to express my gratitude to my friends and family, and most importantly to my
wife, for their wonderful encouragement and support. Also, my biggest thanks go to Packt
Publishing for choosing me to be a part of this awesome book review.
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Table of Contents
Preface 1
Section 1: Introduction
Chapter 1: A Refreshing Look at QGIS 7
Release schedules 8
QGIS downloading and installation 8
Installing QGIS on Windows 8
Installing QGIS on macOS 9
Installing QGIS on Ubuntu Linux 9
Installing QGIS only 9
Installing QGIS and other FOSSGIS packages 10
QGIS on Android 10
Installing QGIS on a Chromebook 11
QGIS in a browser 11
What's new? 11
A tour of QGIS 14
Familiarizing yourself with QGIS Desktop 14
Loading data into QGIS Desktop 15
Loading vector data 16
Loading raster data 17
Loading databases 19
Loading web services 19
Working with CRS 20
Working with tables 20
Creating table joins 22
Editing data 24
Snapping 25
Styling vector data 26
Styling raster data 28
Blending modes 30
Composing maps 30
Adding functionality with plugins 31
Custom QGIS variables 33
Summary 34
Section 2: Getting Started
Chapter 2: Styling Raster and Vector Data 36
Choosing and managing colors 36
Table of Contents
Knowing color picker components 39
Changeable panels in the color picker 40
Color ramp 40
Color wheel 41
Color swatches 41
Color sampler 43
Color picker components in the Layers panel 44
Managing color ramps 46
Managing the QGIS color ramp collection 46
Renaming a color ramp 48
Removing a color ramp 48
Exporting a color ramp 48
Importing a color ramp 49
Adding a color ramp 50
Adding a gradient color ramp 50
Adding a random color ramp 52
Adding a ColorBrewer color ramp 53
Adding a cpt-city color ramp 54
Editing a color ramp 56
Styling singleband rasters 56
Paletted raster band rendering 56
Singleband gray raster band rendering 58
Singleband pseudocolor raster band rendering 61
Singleband pseudocolor interpolations 64
Styling multiband rasters 65
Raster color rendering 65
Raster resampling 68
Styling vectors 69
Single-symbol vector styling 70
Categorized vector styling 73
Graduated vector styling 74
Rule-based vector styling 76
Point-displacement vector styling 79
Point cluster vector styling 81
Inverted polygons vector styling 81
Heatmap vector styling 83
2.5 D vector styling 85
Vector layer rendering 88
Layer transparency 88
Layer blending mode 88
Feature blending mode 89
Control feature rendering order 90
Using diagrams to display thematic data 91
Parameters that are common to all diagram types 92
Diagram size parameters 92
Diagram placement parameters 93
Adding attributes to diagrams 95
[ ii ]
Table of Contents
Creating a pie chart diagram 96
Creating a text diagram 98
Creating a histogram chart diagram 99
Saving, loading, and setting default styles 100
Saving a style 101
Loading a style 101
Setting and restoring a default style 101
Adding and renaming styles in the current QGIS project 102
Summary 102
Chapter 3: Creating Spatial Databases 103
Fundamental database concepts 104
Describing database tables 104
Knowing about table relationships 105
Reviewing the basics of the structured query language 105
Creating a spatial database 106
Connecting to a GeoPackage 108
Importing data into a GeoPackage 108
Importing a vector file 108
Importing a layer from map canvas 109
Working with tables 110
Creating a new table within an existing GeoPackage 110
Renaming a table 111
Editing an existing table field/column 111
Deleting a GeoPackage table 112
Exporting tables out of a GeoPackage 112
Creating queries and views 113
Using select statements 113
Creating a spatial view 114
Dropping a spatial view 114
Summary 115
Chapter 4: Preparing Vector Data for Processing 116
Merging vectors 117
Converting vector geometries 119
Creating polygon centroids 119
Converting lines into polygons 120
Converting polygons into lines 121
Creating polygons surrounding individual points 122
Voronoi polygons 122
Delaunay triangulation 125
Extracting nodes (vertices) 127
Simplifying and densifying features 128
Converting between multipart and singleparts features 129
Adding geometry columns to an attribute table 130
[ iii ]