5). The shape, size, and orientation of the spectral triangle of West Africa changes
constantly due to the diurnal and seasonal temperature variation.
The hump on the right side of the triangle is due to the effect of the clouds,
(Figure 1). Cool clouds shift the land and water pixels with the cloud influence in
the scattergraph towards lower temperature direction. It also can be seen in
Figure 2 that the cloud effects were minimized in the NDVI and TIR model
because NDVI ratioing helped to remove a part of the cloud influence.
The above observations suggest that all land cover types are associated in
the natural environment and can form a global triangle in the two dimensional
space of temperature and vegetation. The concept of the triangle and its changes
through time and potential applications could be represented as follows:
VEGETATION
VEGETATION
Figure 3. Global Triangle and Figure 4. Multi-Date Change Detection
Vegetation Distribution
VEGETATION
Temperature
Day Night
Figure 5 Diurnal Changes of the
Global Triangle
VEGETATION
Figure 6. Distinguish Vegetation
from Background Soils
In Figure 3, temperature increases from right to left on the bottom with a
range of temperature from deep ocean to the temperature of hot desert. Vegetation
