Satellite Image Analysis and
Terrain Modelling
A practical manual for natural resource
management, disaster risk and development
planning using free geospatial data and software.
Version 2
SAGA GIS 4
June 2017
Forward................................................................................................................... 1
1. Introduction ............................................................................................................ 7
1.1 What will you learn............................................................................................ 9
1.2 What is SAGA? ............................................................................................... 11
1.3 SAGA Download and Installation. ................................................................... 12
2. Quick Start ........................................................................................................... 13
2.1 SAGA Layout .................................................................................................. 13
2.2 Import and view digital elevation data ............................................................. 17
2.3 3D Visualisation .............................................................................................. 19
2.4 Import and View Landsat data. ....................................................................... 22
2.5 Displaying Landsat data in SAGA. .................................................................. 23
2.5 Import and viewing Sentinel Data ................................................................... 26
2.6 Adding vector data .......................................................................................... 27
3. Introduction to spatial data concepts .................................................................... 29
3.1 Data Types...................................................................................................... 29
3.2 Vector Data..................................................................................................... 29
3.3 Raster Data..................................................................................................... 30
3.4 Coordinate systems ........................................................................................ 31
4. Introduction to satellite imagery............................................................................ 33
4.1 Key terms in satellite data............................................................................... 34
4.2 What is Landsat? ............................................................................................ 36
4.3 What is Sentinel 2? ......................................................................................... 37
4.4 What is digital elevation data? ........................................................................ 37
5. Accessing free spatial data .................................................................................. 39
5.1 Downloading Landsat and Sentinel 2 imagery ................................................ 39
5.2 Historic Landsat Data downloads – 1972-Present .......................................... 42
5.3 Downloading elevation (SRTM) data........................................................... 44
5.4 Other Global Spatial Datasets......................................................................... 45
6. Visualising satellite data ....................................................................................... 46
6.1 Changing band combination display ........................................................... 46
6.2 Vegetation Indices .......................................................................................... 49
6.3 Producing a higher resolution Landsat display using band 8 .......................... 51
6.4 Multi-temporal image display .......................................................................... 53
6.5 Mosaicking Satellite imagery........................................................................... 54
7. Processing tools................................................................................................... 57
7.1 Coordinate transform ...................................................................................... 57
7.2 Clipping grids with polygons........................................................................... 60
7.3 Reclassification............................................................................................... 61
7.5 Exporting an image map ................................................................................. 66
7.6 Importing Data ................................................................................................ 67
7.7 Field data ........................................................................................................ 68
8. Satellite Image classification ................................................................................ 72
8.1 Object-based classification of Sentinel 2 imagery........................................... 73
8.2 Unsupervised Classification ............................................................................ 79
8.3 Supervised OBIA ............................................................................................ 87
9. Hydrology and terrain modelling........................................................................... 94
9.1 Create watershed basins ................................................................................ 95
9.2 Basic Terrain Analysis..................................................................................... 99
9.3 Hydrological flow modelling........................................................................... 103
10. Application examples ....................................................................................... 105
10.1 Using Object-Based Image Analysis in SAGA to map fire extent........... 106
10.2 Forest cover change mapping using Image differencing............................. 111
10.3 Assessing sediment flows from a field survey of small-scale mining in west
Timor................................................................................................................... 122
10.4 Assessing potential toxic heavy metal flows from a satellite-based
assessment of a small-scale mining area in South East Sulawesi...................... 126
11. Advanced concepts......................................................................................... 135
11.1 Tool Chains................................................................................................. 136
11.2 Travel time analysis tools............................................................................ 137
11.2 Error matrix ................................................................................................. 144
11.4 Atmospheric Correction............................................................................... 146
11.5 Troubleshooting .......................................................................................... 147
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