Geography Reference
In-Depth Information
photogrammetric flights for systematic cartography are again being contracted in greater
quantity, making more data aimed at greater scales available (mainly 1:25,000 or above), in
addition to a growing offer of LIDAR and RADAR data. Regarding this latter sensor - the
project “Amazon Radiography” is presently ongoing, with the use of airborne
interferometer RADAR, in the X and P bands, for production of a cartographic reference
base in scale 1:50,000 and 1:100,000, among other products in [21].
One feature that may soon become more common for orbital sensors is the planning of Earth
observation missions that count with a constellation of satellites as for instance, Rapideye.
Obviously, besides technical issues, the constellations tend to favor the reduction of interval
revisits, increasing the chance of success in the acquisition of data in the area desired.
Another important remark is the appearance of new spectral bands of high spatial
resolution, such as the coastal, yellow and red edge, which offer new investigation
possibilities for the enhancement of thematic maps.
With increasingly better orbital and attitude control systems, image suppliers have been
offering products with geolocation which are increasingly accurate, at least in areas with flat
topography. In some cases those images may even dispense the need for geometric
correction for users who work in scales which do not demand great accuracy. Orthorectified
images can even be acquired for some products, without the need for the user to supply
ground control points.
The possibilities seem endless, with new offers of data and applications arising constantly.
However, a critical eye should be kept on each input or product, in order to know their real
potentialities and limitations.
8. Conclusion
With the systematic offer of new and re-paged sensors, it is increasingly difficult to close a
discussion on the subject. It is a fact that Remote Sensing is becoming indispensable for
many cartographic applications, for all its already mentioned facilities. With all this, in the
present phase, it is extremely important that the investments for assessment of so many
products offered are made, in order to direct them to a conscious use, with awareness of the
problems involved, thus avoiding loss of time and resources. The existent shift from analog
to digital paradigm is also emphasized, which becomes an additional requirement in the
reassessment of methods and processes, not only of products.
Still regarding the new sensors, one may state that the present scarcity of sensors of medium
resolution has become a serious problem in mapping and monitoring of natural phenomena
and events, mainly in countries with great territorial extensions such as Brazil. It is
fundamental and urgent that investments be made in the sector. On the other hand, we
emphasize our present concern with the maintenance and the investments in remote sensors
that seek to meet the requirements of global studies (low resolution and great coverage), as
in the case of climate changes, and local studies (high resolution), as for instance sensitivity
and risk maps in support of natural disasters.
