Applications
Natural
resource management is a broad field covering many different application areas
as diverse as monitoring fish stocks to effects of natural disasters (hazard
assessment).
Remote
sensing can be used for applications in several different areas, including:
q
Geology
and Mineral exploration
q
Hazard
assessment
q
Oceanography
q
Agriculture
and forestry
q
Land
degradation
q
Environmental
monitoring,…
(Each sensor was designed with a
specific purpose. With optical sensors, the design focuses on the spectral
bands to be collected. With radar imaging, the incidence angle and microwave
band used plays an important role in defining which applications the sensor is
best suited for.)
Each
application itself has specific demands, for spectral resolution, spatial
resolution, and temporal resolution.
For
a brief, spectral resolution refers to the width or range of each spectral band
being recorded. As an example, panchromatic imagery (sensing a broad range of
all visible wavelengths) will not be as sensitive to vegetation stress as a
narrow band in the red wavelengths, where chlorophyll strongly absorbs
electromagnetic energy.
Spatial
resolution refers to the discernible detail in the image. Detailed mapping of
wetlands requires far finer spatial resolution than does the regional mapping
of physiographic areas.
Temporal
resolution refers to the time interval between images. There are applications
requiring data repeatedly and often, such as oil spill, forest fire, and sea
ice motion monitoring. Some applications only require seasonal imaging (crop
identification, forest insect infestation, and wetland monitoring), and some
need imaging only once (geology structural mapping). Obviously, the most time-critical
applications also demand fast turnaround for image processing and delivery -
getting useful imagery quickly into the user's hands.
(Let as consider an application, in
concrete the use of remote sensing in the forest inventory. Forest inventory is
a broad application area covering the gathering of information on the species
distribution, age, height, density and site quality.)
For
species identification, we could use imaging systems or aerial photos.
For
the age and height of the trees, radar could be used in combination with the
species information assessed at a first stage.
Density
is achieved mainly by an optical interpretation of aerial photos and/or
high-resolution panchromatic images.
As
for site quality, is one of the more difficult things to assess. It is based on
topological position, soil type and drainage and moisture regime. The
topological position can be estimated using laser or radar. However, the soil
type and drainage and moisture regime could be more profitably collected using
ground data.
The use of Remote Sensing in Crop
monitoring (real case)
The
countries involved in the European Communities (EC) are using remote sensing to
help fulfill the requirements and mandate of the EC Agricultural Policy, which
is common to all members. The requirements are to delineate, identify, and
measure the extent of important crops throughout Europe, and to provide an
early forecast of production early in the season. Standardized procedures for
collecting this data are based on remote sensing technology, developed and
defined through the MARS project (Monitoring Agriculture by Remote Sensing).
The
project uses many types of remotely sensed data, from low resolution
NOAA-AVHRR, to high-resolution radar, and numerous sources of ancillary data.
These data are used to classify crop type over a regional scale to conduct
regional inventories, assess vegetation condition, estimate potential yield,
and finally to predict similar statistics for other areas and compare results.
Multisource data such as VIR and radar were introduced into the project for
increasing classification accuracies. Radar provides very different information
than the VIR sensors, particularly vegetation structure, which proves valuable
when attempting to differentiate between crop types.
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