Image Processing Reference
In-Depth Information
Figure3.20 Radar image of Maat Mons. (CourtesyofNASA)
two dissimilar materials (dirt and a mine's plastic casing, for example). The radar
receiver records the strength of the return echo and the round-trip time (the time for
the signal to be emitted, reflect off a boundary, and return). Because the pulses are
extremely short, the radar can be used at very close range and is ideal for imaging
landmines buried several centimeters deep in soil.
The left image in Fig. 3.21 is a photograph of an antitank mine prior to burying
at the Nevada Test Site. MIR imaging enables a mine sweeper to image “slices”
of the mine, corresponding to different depths under the soil surface. This slicing
method makes it much easier to discriminate between a mine and a square piece
of buried metal debris, as the internal structure of the mine has a distinctive shape
or “signature,” as shown in the right image in Fig. 3.21. The mine is the large
square object with a roughly circular opening in the middle, with a bright square
object within the circle. This circular opening is the pressure plate that triggers the
mine when a tank drives over it, and the bright object within is the detonator. MIR
imaging has many potential uses in the fields of law enforcement and archaeology
for the detection of objects hidden inside concrete, within stone, or behind brick
walls. Figure 3.22 are visible-light and MIR views of a 30-cm-thick concrete slab
Figure3.21 Visible (left) and MIR (right) images of an antitank mine. (Courtesyof
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