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Chapter 8

Chapter 8. Remote Sensing & GIS Integration. Basics. EM spectrum: fig p. 268 reflected emitted detection film sensor atmospheric attenuation. Recording type. analog (film) must retrieve film resolution based on film type digital easier to retrieve data

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Chapter 8

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  1. Chapter 8 Remote Sensing & GIS Integration

  2. Basics • EM spectrum: fig p. 268 • reflected • emitted • detection • film • sensor • atmospheric attenuation

  3. Recording type • analog (film) • must retrieve film • resolution based on film type • digital • easier to retrieve data • resolution based on sensors/unit area • RASTER DATA

  4. System classifications • Passive systems • use existing source of EM illumination • Active systems • provide source of EM illumination

  5. Platforms • airplane • low & high altitude • high resolution • large scale • satellite • various altitudes • low to high resolution • small to large scale

  6. Imaging characteristics • spatial resolution • most important characteristic • basis • lens • film or sensor • ground resolution • spatial resolution • scale

  7. Imaging characteristics • spectral resolution • EM wavelengths to which a system is sensitive • components • number of bands (more is better) • width of bands (narrow is better) • radiometric • differences between “steps” in exposure • contrast • temporal (daily, monthly, yearly, etc.)

  8. Selecting image characteristics • “appropriate” specifications • ground resolution • bands & widths • spectral resolution • determine • what you need to observe • what you might want in the future • what you can afford

  9. Photogrammetry • obtaining reliable measurements from images • science • art • scale - based on: • focal length • height of plane • average terrain elevation

  10. Photogrammetry • sources of error • relief displacement (due to central perspective) • aircraft tilt • orthophotographs/orthoimages • correct for above errors • use digital elevation model (DEM)

  11. Photogrammetry • thermal infrared (TIR) • sense heat • systems: TIMS & ATLAS • panoramic distortion (fig p. 280)

  12. Photogrammetry • side-looking airborne radar (SLAR) • oblique view (side view) • feature foreshortening (compression of features tilted toward radar) • incidence angle varies with distance from radar • resolution varies with • pulse length • antenna size

  13. Photogrammetry • satellite • all types of images • advantages • wider coverage • tilt-free • little relief displacement • disadvantages • low spatial resolution (Landsat TM is 30m, SPOT is 20m)

  14. Extraction of Data • steps (fig p. 290) • detection • identification • analysis and deduction • classification • theorization (verify/nullify hypotheses)

  15. Image elements • tone/color – least complex • size • shape • texture • pattern • height • shadow • association • pattern – most complex

  16. Computer-assisted classification • classifying raster data • automate of low complexity functions • preprocessing: radiometric & geometric correction • classification approaches • supervised – classes assigned - fig p. 293 • unsupervised - cluster analysis • hybrid – unsupervised followed by supervised

  17. Computer-assisted classification • types of classifiers • hard vs soft – fig p. 295 • contextual – looks at neighboring pixels • artificial neural networks • complex determinations based on multiple inputs - fig p. 296 • field checking

  18. Change detection • overlay • map-to-map • image-to-image • output • matrix • map • fig p. 297

  19. Integration of GIS & Remote Sensing • requirements • same georeferencing system • rectify or register • resampling • problem: raster-vector data styles • three stages – fig p 299 • separate but equal • seamless integration (ArcView) • total integration

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