Re: Seeing the past covered by grass - FYI

["Lee Tarpley" <tarpley@xxxxxxxxxxxxxx>]

> NASA uses ground imaging RADAR. good for about 12 inches or so into the
dirt. other people
> used it to find stuff in the desert in Iraq.
>
> >>> <shopper@xxxxxxxx> 7/11/99 8:41:48 PM >>>
> Andrew,  isn't this the same as some of NASA's ground imaging?
> Albeit about a $1 billion less expensive?    I saw some prints which
> revealed paths made by Mayas and abandoned centruies ago, but
> the compacting of the earth is revealed with IR.
>
> Jim

Foliage, including turf, does not strongly absorb the very near infrared
radiation, allowing some radiation to penetrate, and reflect from, the
underlying soil. If the soil covering the buried structure (the sidewalk)
differed, then this difference could potentially be detected in the very
near infrared. Alternatively, the turf density could differ if the presence
of the underlying structure altered root growth patterns. The difference in
density might be more easily detectable in the very near infrared. In an
interesting application, reflectance of visible through near-infrared
radiation has been used to identify sites of buried mines, but this is not
detecting the buried structure directly, but rather changes in the overlying
soil and vegetation.

Lee Tarpley

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