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A Gentle Introduction to SAGA GIS

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A Gentle Introduction to SAGA GIS A gentle introduction to SAGA GIS V´ıctorOlaya Edition 1.1 — Rev. December 9, 2004 A gentle introduction to SAGA GIS. Copyright c 2004 Victor Olaya Edition 1.1 Rev. December 9, 2004 Revised by Javier Pineda (AESIA Desarrollo y Proyectos Medioambientales, S.L., Madrid, Spain.) and Victor Olaya. Permission is granted to copy, distribute and/or modify this document under the terms of the Creative Commons Attribution–ShareAlike license. A copy of the license can be downloaded from the Creative Commons website at www.creativecommons.org. The license applies to the entire text of this book, plus all the illustrations that are by Victor Olaya. All the illustrations are by Victor Olaya except as noted in the photo credits or in parentheses in the caption of the figure. This book can be downloaded free of charge from http://geosun1.uni-geog.gwdg.de/saga/html/index.php in a variety of formats, including editable formats. Windows is a registered trademark of Microsoft Corporation in the United States and other countries. Linux is a registered trademark of Linus Torvalds. All other trademarks and service marks that might appear in this work are the property of their respective owners. You are free: • to copy, distribute, display, and perform this work • to make derivative works • to make commercial use of this work Under the following conditions: • Attribution. You must give the original author credit. • Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one. • For any reuse or distribution, you must make clear to others the license terms of this work. • Any of these conditions can be waived if you get permission from the copyright holder. Your fair use and other rights are in no way affected by the above. For any further information, please contact the author at the following e–mail address [email protected] This book can be downloaded in PDF and LATEXformats from the following website: http://geosun1.uni-geog.gwdg.de/saga/html/index.php Acknowledgments This book will not be the same without the contribution of the following people, to whom I am in debt: • Javier Pineda from Aesia Desarrollo y Proyectos Medioambientales S.L, who painstakingly read the text and corrected many of my mistakes. However, if you still find any mistake, I’m the one to blame, not him. • Andre Ringeler from the SAGA Development Team, who supported the manual from the very beginning and showed great interest. Also, the chapter about programming is based in his great text First steps in SAGA modules programming, from which I borrowed many ideas and even some text fragments. vii Contents Acknowledgments vii Preface xiii 1 Introduction 1 1.1 Introduction.What is SAGA? . 1 1.2 Who has created SAGA? . 2 1.3 How can I get SAGA? . 2 1.4 Installing and running SAGA . 3 2 SAGA fundamentals 5 2.1 Introduction . 5 2.2 The SAGA GUI . 5 2.3 Preferences. The parameters window. 8 2.4 Projects. File handling . 10 2.5 The SAGA module structure . 14 2.6 Closing SAGA . 15 3 Working with grids 17 3.1 Introduction . 17 3.2 Displaying grids. Basic tools . 17 3.3 Adjusting grid rendering . 19 3.4 Memory handling. Saving grids . 29 3.5 3D views . 30 3.6 Basic analysis functions . 32 3.6.1 Frequency histograms . 32 3.6.2 Profiles . 34 3.6.3 Regression analysis . 36 4 Working with tables 39 4.1 Introduction . 39 4.2 Opening and editing tables . 39 4.3 Creating a table . 40 4.4 Creating diagrams . 41 5 Working with shapes 43 5.1 Introduction . 43 5.2 Displaying vector data . 44 5.3 The attributes table . 48 5.4 Editing vector data . 49 ix 5.4.1 The vector hierarchy . 50 5.4.2 Editing shapes . 51 5.4.3 Adding a new shape to the layer . 53 5.4.4 Creating a vector layer . 53 6 Creating layouts 55 6.1 Introduction . 55 6.2 Creating a layout . 55 6.3 Adding grids . 56 6.4 Adding grid leyends . 58 6.5 Adding a histogram . 59 6.6 Adding a profile . 60 6.7 Adding 3D Views . 60 6.8 Adding shapes . 60 6.9 Adding text . 61 6.10 Arranging layout elements . 61 6.11 Once the layout is finished . 63 7 A first step into modules. Some basic grid modules 65 7.1 Introduction . 65 7.2 Filtering a grid . 65 7.3 Arithmetic mean of grids . 68 7.4 Normalizing a grid . 69 7.5 The Grid Calculator . 69 7.6 Changing the data storage type . 72 7.7 Changing grid orientation . 73 7.8 Changing grid values . 74 7.9 Resampling a grid . 76 7.10 Merging grids . 79 7.11 Filling missing information . 80 7.12 Creating buffers . 81 7.13 Creating artificial grids . 83 7.14 Some examples . 85 7.14.1 Performing grid intersection . 86 7.14.2 Using masks . 88 8 Import/Export modules 91 8.1 Introduction . 91 8.2 Import modules . 91 8.3 Export modules . 94 9 Terrain analysis. Hydrology. Lighting 97 9.1 Introduction . 97 9.2 Basic morphometric analysis . 97 9.3 Creating an hypsometric curve . 103 9.4 Classificating terrain forms . 104 9.5 Preparing a grid for hydrological analysis . 105 9.6 Calculating catchment area . 106 9.7 Calculating upslope and downslope areas . 112 9.8 Some hydrological indices . 116 9.9 Defining channel networks . 118 9.10 Basins . 121 9.11 Distances to channel network . 122 9.12 Calculating time to outlet. Isochrones . 124 9.13 Other hydrological parameters . 126 9.14 Lighting . 127 10 Shapes Modules 133 10.1 Introduction . 133 10.2 Combining raster and vector layers . 133 10.2.1 Creating contour lines from a grid . 133 10.2.2 Vectorising grid classes . 134 10.2.3 Converting a vector layer into a grid . 135 10.2.4 Retrieving grid information to enrich raster layers . 137 10.3 Creating a points layer from a table . 138 10.4 Merging vector layers . 139 10.5 Joining tables . 140 10.6 Intersecting polygon layers . 141 10.7 Calculating geometrical properties of polygons.
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