High Resolution 1:10,000 scale Mapping Strategy of Multi ... - NDMA

more detail, less coverage. The skilled management of collection results in cost
effective collection and avoids situations such as the use of multiple high resolution
data which tends to clog transmission and storage infrastructure.
IMAGING PROBLEMS IN SATELLITE MAPPING
The human eye is able to separate approximately 64 grey values (6 bit), but it
can adapt very well to the brightness. The imaging sensors cannot change the
sensitivity very fast without influence to a homogenous image quality, by this reason
they must be able to separate quite more grey values.
� Modern CCD sensors used in space do have a radiometric resolution up to 11
bit, corresponding to 2,048 different grey values. Usually there is not a good
distribution of grey values over the whole histogram, but the important part
can be optimized for the presentation with the 8 bit grey values of a computer
screen.
� The higher radiometric resolution includes also the advantage of an optimal
use of the grey values also in extreme cases like bright roofs just beside
shadow part. By high pass filter the important information for mapping can be
optimized.
� Also for 11 bit-sensors, there are some limits. If the sun light will be reflected
by a glass roof directly to the sensor, an over saturation will occur and the
generated electrons will flow to the neighbored CCD-elements and the readout
will be influenced over short time. The over-saturation does not causing
problems, but the human operator should know about it to avoid a
misinterpretation of the objects.
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