Training Module on Monitoring Vegetation From Space

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• 3 - Satellite sensors and vegetation
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• 3.1 - Spectral response of different surfaces
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• 3.2 - Fundamental factors affecting vegetation reflectance
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• 3.3 - The importance of spectral resolution
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• 3.4 - Satellite sensors sensitive to vegetation
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• 3.5 - RGB images

3.5 - RGB images

RGB images can be used to extract information about vegetation cover. RGB techniques work by associating a colour to a particular channel.To extract maximum information from a single image each colour (Red, Green or Blue) should be associate to a different channel with distinct physical properties.

To extract information about vegetation cover, the RGB composite 1.6; 0.8; 0.6 μm, often referred as "Day natural colours" composite, can be used.

In this composite Red is associated to NIR 1.6 μm; Green to VIS 0.8 μm and Blue to VIS 0.6 μm. So as you can see in the image:

Figure 3.11: Meteosat-9 colour composite image of 1.6 μm, 0.8 μm and 0.6 μm

• Reddish/pink is dominant for bare soil and arid regions.
• Green is the dominant component for vegetation.
• Cyan is evident in ice clouds.

A complete description of how to apply RGB techniques in satellite images and forecasting, can be found in https://resources.eumetrain.org/IntGuide/