Lecture 4 - Interaction of visible and NIR with Earth Surface Flashcards
(15 cards)
Remote Sensing provides means for analysing soil in what ways?
- Map soil aerial coverage
- Estimate soil physiochemical properties
Factors affecting spectral reflectance of soil
- Soil Moisture content
- Organic content
- Structure
- Mineralogical composition
What does high soil moisture content result in for reflectance?
Decreased reflectance throughout visible and NIR region, especially in 1400-1900 mm water absoprtion bands.
Iron Oxide within soil
Leads to higher reflectance in red wavelength
Absorbs in blue, green and NIR wavelengths
What does a NIR image of water show?
Only contrast between water and land as water absorbs all of the light.
3 types of reflectance from water
Surface reflectance
Volume reflectance
Bottom reflectance
What does volume reflectance provide?
Info on water quality due to materials in the wateras light is reflected
Shallow water
Most reflectance is from the bottom so:
- less info about water quality
- Mapping coral reefs
What is used to detect presence of live coral?
Hyperspectral (400 wavebands) imagery
Surface roughness
Tends to decrease observed reflectance
Uses of surface roughness in RS
Pollution Mapping
Submarine topography
Wave Formation
Whats mainly used to measure soil moisture content?
Microwaves
How does higher soil moisture reduce reflection?
Water fills in airspaces so reduces the amount of scattered light and this influences the visible and NIR wavelengths and reduces their reflectance
Reflectance in water
Low reflectance in visible, NIR and SWIR, higher reflectance in blue and green.
Reflectance in water
Low reflectance in visible, NIR and SWIR, higher reflectance in blue and green.
