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Post Info TOPIC: How to interpret color infrared


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How to interpret color infrared


I have been getting a lot of questions about the color infrared aerial photography.  Basically how to interpret it.

Basically I tell them that red is healthy vegetation, but there must be more there as well.  What about the other colors?

What other things can we get out of the IR photo?  For example, I thought clear water was supposed to be black, but swimming pools seem to be the regular blue color like we see in the natural color.  Why is that?  Is our IR not really IR?

How about heat?  Can we see that in our IR photo?  What colors should we be looking for?

Looking forward to everyone's interpretations!

mike

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Michael A. Carson, GIS Coordinator, City of Santa Monica


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Mike,

I'm only peripherally aware of the LAR-IAC data particulars but Im guessing youve got a combination of NearIR/Green/Blue or NearIR/Red/Green/Blue.

If confirmed, you can elaborate your answers to your clients using the following sample vegetation spectral graph (see below). The pigments (chlorophyll) vary from plant to plant but the following spectral graph represents how floristic reflectivity/absorbance can be characterized. Check the specs on the dataset to see what range of IR it covers (typically digital covers a more refined range within 0.76~0.97mu).
SpectralSignature

So your IR is truly IR. However if I'm right, the rest of the bands are nothing more unusual than what you see in true color. 

As for heat, thermal radiance is much higher up the EM spectrum (<10mu) so the answer in short, is no.
 

For a crash course in remote sensing, try http://rst.gsfc.nasa.gov/




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