Spectral reflectance curve of dead stressed vegetation

Spectral reflectance curve of dead stressed vegetation

1. Group Members Junaid Gurmani Wajahat Saadat Daud Amir Sohaib Arshad Muhammad Salman Mohammad Aqib Asfand Lashari Spectral Reflectance Curve of Dead/Stressed Vegetation

2. Spectral Reflectance The reflectance characteristics of Earth’s surface features may be quantified by measuring the portion of incident energy that is reflected. This is measured as a function of wavelength (λ) and is called spectral reflectance ( rλ ). Reflectivity is the fraction of incident radiation reflected by a surface.

3. S pectral signature Spectral signature is the variation of reflectance or emittance of a material with respect to wavelengths.

4. Spectral Response The spectral response describes the sensitivity of the photo sensor to optical radiation of different wavelengths. This is important because only a small part of the optical radiation spectrum is visible . Spectral reflectance A curve that illustrates the reflectance of light from a surface. Spectral reflectance curves are used to determine color ,  brightness, and witness important optical properties.

5. Typical spectral reflectance curves for vegetation, soil and water

6. Albedo and Spectral Reflectance The fraction of the total light striking a surface that gets reflected from that surface while reflectance is defined as this same fraction for a single incidence angle A lbedo is the directional integration of reflectance over all sun-view geometries . An object that has a high albedo (near 1) is very bright; an object that has a low albedo (near 0) is dark. The Earth's albedo is about 0.37. The Moon's is about 0.12.

7. Dead/Stressed Vegetation Any unfavorable condition or substance that affects or blocks a plant's metabolism, growth, or development and when the chlorophyll has been damaged by a lack of nutrients or intake of harmful particulates.

8. Interaction Of EMR With Vegetation Chlorophyll is a pigment which absorbs solar radiations, this is achieved by absorption near 0.45 and 0.68 μm in the blue and red part of the visible spectrum , often called the “Chlorophyll Absorption Bands, which is why healthy leaves appear green

9. Water in the cells also absorb some energy. Relative reflectance is higher in the visible green than in blue and red ,thus giving the vegetation visible green color Reflectance is much higher in reflective IR region than visible. Healthy vegetation look very similar in the visible part of the spectrum but can be distinguished in NIR.

10. Dead vegetation reflects greater amount of energy than healthy green vegetation throughout the visible spectrum (0.4-0.7 μm )

11. If a plant is subject to some form of stress that interrupts its normal growth and productivity, it may decrease or cease chlorophyll production. This result is less chlorophyll absorption in the blue and red bands. Often, the red reflectance increases to the point that we see the plant turn yellow (combination of green and red)

12. From the visible to the near- IRportion of the spectrum at about 0.7 μm , the reflectance of healthy vegetation increases dramatically . In the range from about 0.7 to 1.3 μm , a plant leaf typically reflects 50 percent of the energy incident upon it or it can be more than that.

13. Different types of vegetations