INTRODUCTION REMOTE SENSING

Transcription

1 INTRODUCTION REMOTE SENSING dr.ir. Jan Clevers Centre for Geo-Information Dept. Environmental Sciences Wageningen UR

2 Remote Sensing --> RS Sensor at a distance EARTH OBSERVATION EM energy Earth RS is a tool; one of the sources of information!

3 GIS Geographical Information System Well-considered combination of mutually referring data sets of various kinds of positionbound thematic data (database), software inclusive Requirement: the information layers match geometrically ==> OVERLAY STRUCTURE GIS file: 1. topography 2. soils 3. geology 4. precipitation 5. land cover 6. vegetation 7. remote sensing data 8. surface temperature 9. hydrology 10. population 11. nature conservation 12. environment 13. digital terrain model 14. topographical map field data (point measurements) vector data raster data

4 Meteosat: meteorological satellite

5 Meteosat image of Europe

6 Wageningen, Thematic Mapper Band Veenendaal Ede Bennekom Rhenen Wageningen

7 Rotterdam harbour, daytime

8 Rotterdam harbour, nighttime

9 The remote sensing system A = source B = atmosphere C = object D = sensor E = reception F = data analysis G = final product

10 Source of EM radiation 10 0 radiation (Wcm -2 µm -1 ) 10-1 curves for an average object on earth 10-2 reflected solar radiation emitted thermal radiation wavelength (µm) REFLECTION EMISSION

11 EM Spectrum and Windows reflection emission µm 1mm 1cm 1m 10m atmospheric transmittance blue green red UV VIS NIR MIR MIR TIR TIR blocking effect of atmosphere microwaves photography human eye lidar thermal scanners radar multispectral scanners microwave radiometry µm 1mm 1cm 1m 10m optical window wavelength microwave window

12 Active <-> Passive RS using reflected solar radiation: (PASSIVE) RS using radiation emitted by objects: (PASSIVE) ACTIVE RS:

13 Principles imaging sensor systems analogue recording digital recording digital recording aerial image plane shutter scanning mirror imaging optics line array detector imaging optics point detector imaging optics Camera (aerial photography) Whiskbroom scanner Pushbroom scanner

14 The position of the spectral bands of some Remote Sensing sensor systems in the optical window Meteosat NOAA AVHRR Landsat TM SPOT HRG multispectral SPOT HRG Panchromatic Pan: IKONOS, Quickbird, GeoEye, WorldView Multispectral: IKONOS, Quickbird, GeoEye, WorldView reflectance (%) dry soil 20 wet soil infrared infrared vegetation water λ wavelength (µm) near- middle- blue green red

15 Image Processing Options Tape/Disc: Screen: latent image Visualization picture 1 picture picture n Options: e.g. spectral band selection filtering displaying band composites band ratioing contrast modification vegetation index computation histogram equalization classification grey scale enhancement texture analysis colour assignment segmentation density slicing geometric correction principal components transformation

16 Example TM-image, band (R,G,B)

17 RS Properties Synopsis Flexibility Actuality Interactivity Dynamics Moreover: overview region differences and coherence variety of sensors, techniques, processing algorithms reproducible analysis in addition to conventional mapping specified data for application up to date information co-operation of human knowledge and machine operations capability of monitoring with time series of data reveals changes (change detection) the invisible becomes visible objective and quantitative data extrapolation of point measurements open up inaccessible regions integration with GIS

18 MERIS image of Europe Wageningen UR 2010

19 Satellite based land cover classification

20 Dutch land cover data base LGN5

21 LGN5 detail The Hague - Rotterdam

22 Global land cover classification - MODIS Land Cover Class Fill Value 255 Water 0 Evergreen Needleleaf Forest 1 Evergreen Broadleaf Forest 2 Deciduous Needleleaf Forest 3 Deciduous Broadleaf Forest 4 Mixed Forest 5 Closed Shrubland 6 Open Shrubland 7 Woody Savannas 8 Savannas 9 Grasslands 10 Permanent Wetlands 11 Croplands 12 Urban and Built-Up 13 Cropland/Natural Vegetation Mosaic 14 Snow and Ice 15 Barren or Sparsely Vegetated 16 Unclassified 254 Color Wageningen UR 2010

23 Primary Productivity - June 2005

24 Primary Productivity December 2004

25 Perspective view of the Aletsch glacier (Switzerland)