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Beyond Spectral and Spatial data: Exploring other domains of information: 1

This course delves into various domains of information in remote sensing, such as spectral, angular, multi-temporal, and spatial data, explaining the physical basis for spectral information. Topics include spectral reflectance, factors affecting reflectance/transmittance of plant elements, and interpretation challenges. The relationship between vegetation indices and canopy variables like LAI are explored in varying canopy structures. Microwave data concepts are also covered, focusing on water content and object size relative to wavelength. Ultimately, the course aims to deepen understanding of cover type variations and spectral properties in remote sensing data analysis.

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Beyond Spectral and Spatial data: Exploring other domains of information: 1

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  1. Beyond Spectral and Spatial data:Exploring other domains of information: 1 GEOG3010 Remote Sensing and Image Processing Lewis RSU

  2. Domains of Information • spectral • angular • multi-temporal • distance-resolved • spatial

  3. Domains of Information • consider physical basis for information

  4. Spectral - Physical Basis • Optical • reflectance varies with wavelength • spectral reflectance of different cover types / properties vary

  5. Spectral reflectance • Related to: • how much (projected, illuminated) material seen

  6. Spectral reflectance • Related to: • reflectance / absorptance characteristics of materials

  7. Plus multiple scattering where absorptance low

  8. Leaves • Absorbtance by leaf pigments, water etc • Acting in different parts of the spectrum

  9. Leaves Factors affecting reflectance/transmittance of plant elements • pigment type/concentration • e.g. Chlorophyll a,b - absorb visible radiation • surface features: • hairs, spines, veins, cuticular wax - scattering (e.g. specular) • cell morphology and content • NIR - high refl. due to scattering at refractive index discontinuities (nair = 0; ncell=1.47) • MIR - water absorption features

  10. So …attempt to take RS measurement and relate to • cover type • different spectral properties • amount of material (eg vegetation) • eg leaf • high NIR, low visible (basis of VIs)

  11. Interpretation complicated by: • variations in Sun/view angle

  12. -60 -30 0 30 60 e.g. 5m mean tree spacing SZA = 0 degrees

  13. -60 -30 0 30 60

  14. Interpretation complicated by: projection of objects • orientation (leaf angle distribution)

  15. Interpretation complicated by: projection of objects

  16. Interpretation complicated So relationship between eg VI and canopy variables (LAI) depends on cover type (different canopy structure)

  17. Microwave • Similar ‘spectral’ concepts (frequency c = f ) • again generally related to amount of material • but very much driven by: • water content • size of objects (relative to wavelength) • orientation • effect dept. on polarisation

  18. Summary • Spectral • cover type variation • spectral properties (of leaves, soil etc.) • projected towards viewer, illuminated • depends on amount of material • Vis - e.g. NDVI - quantify amount • relationships depend on cover type

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