Image interpretation. Aliens create Indian Head with an ipod? Badlands Guardian (CBC) This feature can be found 300 KMs SE of Calgary.

Transcription

1 Image interpretation Aliens create Indian Head with an ipod? Badlands Guardian (CBC) This feature can be found 300 KMs SE of Calgary N W

2 Milestones in the History of Remote Sensing 19 th century Invention of photography - use of balloons and kites first aerial photograph from a captive balloon - pigeons - oblique photos (mountain peaks) - Stereo photography -

3 20 th century 1910s First use of aerial photography from planes (World War I: photo interpretation) 1920s Development of photogrammetry for mapping 1940 Military use of radar (World War II) 1945-> Main aerial photo programs in Canada and others 1950s Use of colour photography and infra-red Term 'remote sensing' first appeared (Evelyn Pruit) 1960 First reconnaissance satellites: Corona 1960s First weather satellites: Tiros (1960); Nimbus (1964) (and first digital data transfer)

4 Reconnaissance satellite: Corona ~ 7.5m photos Declassified for environmental studies 2000s Pentagon Mt. Ararat

5 Multispectral image processing: The Landsat Era 1972 Launch of Landsat 1 satellite and the 80metre MultiSpectral Sensor (MSS) 1982 Landsat 4: the 'next generation 30metre sensor: Thematic Mapper (TM) [and Landsat 5 in 1984] 1986 SPOT-1 satellite: 10 and 20metre data (France) 1988 India IRS 1A 5m resolution

6 1990s 1990s Other countries' satellites / sensors: JERS: Japan ERS: Europe RESURS: USSR 1995 Radarsat- Canada's first remote sensing satellite 1999 Landsat 7 Enhanced Thematic Mapper (ETM+); - Reduction of data cost removal of data copyright - enabled online data libraries

7 New millennium events Many new sensors including very high resolution 2000 Terra satellite: ASTER and MODIS data (250m-1km res.) 2000 High resolution private sector satellites: Ikonos (2000) and Quickbird (2001) many more -> present e.g. Worldview Online viewers 2005 Online image viewers- e.g. google earth (ETM+ and high-res.) 2009 Landsat image data archive goes online (free) 2013 Landsat Sentinel 2 (ESA)

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9 Satellite Image interpretation manually uses the same factors as Air photos -Colour -Tone -Texture -Pattern -Shape -Shadow -Size -Association -Multispectral signature -e.g. water reflects no IR

10 Shape: the form of an object on an air photo helps to identify the object. Regular uniform shapes often indicate a human involvement; Pattern: similar to shape, the spatial arrangement of objects (e.g. row crops vs. pasture) is also useful to identify an object and its usage;

11 Shadow: a shadow provides information about height, shape, and orientation Texture: the physical characteristics of an object affects how they appear e.g. calm water has a smooth texture; a forest canopy has a rough texture PCI: TEX

12 Shadows: usually from the SE (~10am)

13 Shadows: (almost) always from the SE Deriba Caldera, Sudan: from the Space Station

14 Great Barrier Reef, Australia

15 Tasmania

16 Size: a measure of the object's surface area (e.g. single-lane vs. multi-lane highways); Time: temporal characteristics of a series of photographs can be helpful in determining the historical change of an area (e.g. looking at a series of photos of a city taken in different years can help determine the growth of suburban neighbourhoods;

17 Association/Site: associating the presence of one object with another, or relating it to its environment, can help identify the object (e.g. industrial buildings often have access to railway sidings; Tone/Colour: the colour characteristics of an object, relative to other objects in the photo (e.g. sand has a bright tone, while water usually has a dark tone; tree species can be determined by the colour of their leaves at certain times of the year);

18 Differences with satellite images (compared to aerial photographs) Spatial resolution Shape and pattern

19 Landsat 5 Air photo

20 Image fusion / pansharpening Goal: Combine higher spatial information in one band with higher spectral information in others to create synthetic higher resolution multispectral images Many sensors have Panchromatic band 2-4 times higher resolution