Briefly describe the spectral curve characteristics of normal and healthy green vegetation.

Ground plants have obvious spectral reflection characteristics, which are different from typical characteristics such as soil and water. The response of vegetation to electromagnetic waves is determined by its chemical and morphological characteristics, which are closely related to the development, health and growth of vegetation. In the visible light band, various pigments are the main factors that dominate the spectral response of plants, among which chlorophyll plays the most important role. The spectral reflection curve of healthy green vegetation almost always presents a "peak-valley" pattern, and the valleys in the visible spectrum are caused by pigments in plant leaves. For example, chlorophyll strongly absorbs the energy of about 0.45um and 0.67um in the center of the spectral band (this band is often called chlorophyll absorption band). Plant leaves strongly absorb the energy in blue and red areas, but strongly reflect the energy in green areas, so healthy vegetation looks green to the naked eye. In addition, lycopene and lutein have absorption bands around 0.45um (blue), but the absorption band of chlorophyll is also in this region, so these two yellow pigments play a leading role in the spectral response mode. If the normal growth and development of plants are interrupted by some form of inhibition, the production of chlorophyll will be reduced or even stopped. This will weaken the blue and red absorption bands of chlorophyll, and often enhance the reflectivity of the red band, so that we can see the plants turn yellow (green-red synthesis). From the visible light region to the near infrared spectrum region of about 0.7um, we can see that the reflectivity of healthy vegetation rises sharply. In the range of 0.7- 1.3um, the reflectance of plants mainly comes from the internal structure of plant leaves. Healthy green plants in the range of 0.7- 1.3um have high reflectivity (45%-50%), high transmittance (45%-50%) and low absorption rate (