Geography Reference
In-Depth Information
(a)
(b)
(c)
(d)
Figure 1.1
Typical Remote Sensing Platforms. a) Landsat-7 satellite (15m spatial resolution), b) QuickBird-2 satellite (61 cm spatial
resolution), c) Full sized fixed wing aircraft operated by the French
Institut Geographique National
(commonly 0.5m spatial
resolution). Copyright IGN - France, d) Ultralight UAS system (1m total wingspan) operated by Durham University, UK.
the satellite and sensor. In the field of airborne remote
sensing the distinction is usually clearer since a given
sensor can usually be mounted on a range of fixed wing
aircraft or helicopters.
Unsurprisingly, there is currently an abundance of
remote sensing images and products. Finding a starting
point and locating an appropriate data source and/or
acquisition method can therefore be quite a daunting
process.Herewe give a short descriptionof remote sensing
data sourcesmost likely tobe of use in the context of fluvial
sciences and river management. Many river managers are
still under the impression that fluvial remote sensing is
not an appropriate tool for river environments. This is
a reasonable viewpoint if we consider the most classic
and widely known remote sensing data: Landsat imagery.
With spatial resolutions of typically 15 mor 30m, Landsat
images only sample river outlines accurately for very large
rivers. Clearly, such imagery has little to offer a manager
or scientist needing to characterise a small stream with
widths below 50m. However, there has been remarkable
technological progress in imaging which has now made
images with resolutions of less than 1m available globally.
Several satellites now offer image resolutions below 1m
and low altitude airborne colour photography is now
capable of resolutions as low as 2-3 cm. The availability
of such data, offering a 100-fold improvement in spatial
resolution when compared to classic Landsat, has been
an important driver of methodological progress in fluvial
remote sensing (see Marcus and Fonstad, 2008).
For readers who are unfamiliar with the topic, Table 1.2
gives a very brief summary of a few key satellites and plat-
forms which are likely to be of interest to river scientists
and managers. We have also included some older plat-
forms that may be of lesser interest in a modern context
but which nevertheless often appear in publications. This
list is far from complete or exhaustive. Our aim is merely
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