1. SATELLITE IMAGE INTERPRETATION Course: Introduction to RS & DIP Mirza Muhammad Waqar Contact: mirza.waqar@ist.edu.pk +92-21-34650765-79 EXT:2257 RG610

2. Contents 2  Geographical Information System  Remote Sensing & Satellite Image Processing  Color Space  Landsat 7 spectral bands  Spectral Reflectance Curves  Image Interpretation  Spectral Ratioing  Indices

3. Software Geographical Information System (GIS) Data Site Suitability Analysis Spatial Analysis 3D Analysis Hydrological Analysis Finding Shortest Path Finding Closest Facility Change Detection Methods

4. Remote Sensing & Satellite Image Processing

5. Spectral vs Spatial  Spectral pattern recognition Family of classification procedures that utilize pixel by pixel spectral information as the basis for automated land cover classification.  Spatial pattern recognition Categorization of image pixels on the basis of their spatial relationship with pixels surrounding them.

6. 6 Landscape visualization  The ground view  Field investigation and survey  Great details, sample taken and field measurements  High cost, time consuming, physically demanding  The bird-eye view  Natural observation, perspective view  Difficult for mapping and locationing  The orthographic view  Professional aerial survey and space mapping  High locational accuracy, fast coverage, economic  Lack of 3-dimensional information, skill demanding

7. 7 The ground view Ground view of Mt. Everest, the highest spot on earth.

8. 8 Visualization – Bird-Eye View Bird-eye view of Mt. Everest. The photo was taken by astronauts on the International Space Station.

9. 9 Visualization – Orthographic View Orthographic view of Mt. Everest. The photo was taken by astronauts on the International Space Station in 1993.

10. 10 The concepts of image interpretation  Image interpretation: the process of identifying objects or conditions in images and determining their meaning or significance.  The interpreter’s task: use scientific tools and methodology to arrive at objective findings.  Geographical knowledge is needed to relate the visible characteristics on the image to the real-world geographical features, even though some of these features may not be physically visible.

11. 11 Spatial interpretation  Spatial interpretation means identifying geographical features using spatial characteristics of objects shown on images.  The most important tasks for spatial interpretation is to establish interpretation keys, i.e. identifying the typical spatial and spectral patterns of known geographical features.

12. 12 Multi-runway airfield used by carrier- based pilots for practicing short takeoffs and landings (Broward County, Florida) Low-altitude photograph of the Pentagon Building, headquarters of the US Department of Defense Obvious features

13. 13 Keys for image interpretation  Shape  Size  Pattern  Shadow  Tone or colour  Texture  Association  Site

14. 14 Shape Some man-made features have unique shapes. Alluvial fans along the east side of Death Valley, California. Alluvial fans can be easily recognised by their fan shape and adjacency to mountain fronts.

15. 15 Pyramids Ground view of the Great Pyramids, Egypt.

16. 16 Shape Centre-pivot irrigation system in Morrow County, Oregon. Most of the fields are planted with wheat. Alluvial fans at the north of Turpan Depression, Xinjiang, China.

17. 17 A Centre-Pivot Irrigation System A centre-pivot irrigation system in Ili, Xinjiang, China.

18. 18 An Alluvial fan Ground view of alluvial fans at the north of Turpan Depression, Xinjiang, China.

19. 19 Size Panchromatic photo of Bangkok, 1982. Note the size of buildings tends to indicate the nature and usage of them.

20. 20 The contrast between sand dunes (left) and loess (right) landscapes found near Yulin, Shannxi, northern China. The mobile sand dunes are well recognised by their repeated patterns, while the high density of gullies of the loess landscape suggests severe soil erosion and mass movement. Pattern

21. 21 Natural Patterns The patterns of forest and wetland show significant variation on remotely sensed images.

22. 22 Loess Landscape The high density of gullies is the key for image interpretation of the loess landscape.

23. 23 Shadow Shadow shown with low sun angle is the key to the interpretation of shape of Mt. Everest.

24. 24 Tone and colour are used to identify agricultural fields. The fields with crops or harvested are clearly separated by their tones and colours. Also note the tone difference shown on the bare fields indicating different soil moisture contents. Tone or Color

25. 25 Texture Textures associated with forest, pasture and cropland. The colour photograph shows the strong contrast in texture between forest (dark and coarse), pasture (light and smooth and farmland (light and smooth with regular road and drainage network).

26. 26 A chain of oasis is located along the toe of an alluvial fan in Turpan Depression, Xinjiang, China. There is a good supply of shallow groundwater to support irrigation system and human settlement in the extremely dry area. Association

27. 27 Sea Port at Kowloon Peninsula of Hong Kong. The site is characterised by regular shore line and large concrete area of loading zones. The extensive transportation network also a good key to identify the port. Site

28. 28 Spectral interpretation  The spatial interpretation keys are also employed to interpret multi-spectral images.  Scale  Spatial distortion  Multi-spectral images, however, add one more dimension (i.e. the spectral space) for image interpretation.  Understanding spectral signature is therefore mandatory for image interpretation.

29. Color Space Red + BlueMagenta Green + BlueCyan Red + Green Yellow Primary Colors Magenta + Cyan Blue Yellow + Cyan Green Yellow + Magenta Red Secondary Colors

30. Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Landsat 7 Wavelength (micrometers) Resolution (m) Band 10.45 - 0.5230 Band 20.52 - 0.6030 Band 30.63 – 0.6930 Band 40.77 – 0.9030 Band 51.55 – 1.7530 Band 610.40 – 12.5060 Band 72.09 – 2.3530 Band 80.52 – 0.9015

31. Spectral Reflectance Curves of Different Land Covers Source: Yasir Yaqoob Wateen Telecom

32. Reflection of Different Land Covers in Landsat Bands *VegetationSoilSnowCloudWater Band 110 %20 %97 %70 %5 % Band 217 %24 %96 %70 %8 % Band 310 %28 %94 %70 %2 % Band 448 %35 %85 %66 %1 % Band 538 %50 %10 %52 %1 % Band 720 %55 %8 %53 %1 %

33. Islamabad Capital Territory – Raw Image Vegetation: Green Dominating Yellow Soil:? Snow:? Cloud:? Water:? Band Combination RGB:542 Vegetation: R=38% G=48% B=17% Grey Tone=17% ----------------------- R=21% G=31% B=0% Yellow Tone= 21% ----------------------- R=0% G=10% B=0%

34. Questions & Discussion