Besides two imaging sensors on board of helicopter Bell-206,
was used hyper spectral line scanner in sampling mode, see.
Section 6. The airborne multisensor system on board of
helicopter Bell-206 was aimed primarily for minefield
research, for general survey (as a complementary process to
the ground based general survey), but it is not limited only to
these purposes and other applications are possible (Bajic M.,
Gold H., 2002).
This is first fully digital airborne multisensor system in
Croatia, its development and use were motivated and
enabled due to scientific project ARC funded by EC.
6. Airborne hyper spectral sampling
Hyper spectral line scanner (HSS) was integrated on board of
helicopter Bell-206 and can be used in the same time as
VNIR sensor. While both VNIR and HSS are collocated in
the same gimbal, Fig. 10, the VNIR image can serve as
reference for interpretation of the hyper spectral sampled data
of the mapped area, Fig. 13, Fig. 14.
Figure 13. Example of the hyper spectral samples acquired
over minefield 31076 in the region Fig. 1. Red polygon is
border of the minefield, blue strips are sampled areas.
Figure 14. Reflection coefficients measured by hyper spectral
scanner V9 on board of helicopter Bell-206. Example for one
blue strip from Fig. 13. Strip 62 x 0.35 m, was divided into
146 pixels, and for each pixel was measured and calculated
coefficient of reflection (not normalised). Horizontal axis
shows wavelength, vertical axis shows reflection coefficient.
Airborne hyper spectral acquisition is new tool now available
in Croatia for measurements of the spectral dependence of the
reflection. Further technical development and the
development of its use is under way, this paper is invitation
for cooperation.
24
Discussion
Main attention in the paper was focused on two advanced
scientific projects SMART and ARC, funded by European
Commission, both about aerial minefield detection and about
related issues. While more comprehensive information are
available elsewhere (EC IST SMART, 2000), (EC IST ARC,
2000), we will here shortly discuss achieved and approved
potentials, constraints and already achieved benefits.
SMART provides at output a system of validated software
tools, integrated in the GIS environment, that enable aimed
interpretation of the mined scene, starting by airborne
images, having spatial resolution from 1 m to 4 m and very
high spectral resolution (4 bands active, SAR; 12 bands
passive multispectral DAEDALUS) and by contextual data.
Data fusion is foreseen for interpretation in the case of
imperfection of images, and of other data. Images and data
are available for approximately 50 km? of the minefields and
suspected areas, Fig. 1 to Fig. 4. Further image and data
acquisition is not provided yet and depends on the results of
the final validation of the project (end 2004).
ARC provided a system for the safe automatic pyramidal
acquisition of images from 30 m to 900 m, without man on
the aerial platform. There are only four wavelength ranges (2
in visible, one near infra red one thermal infra red) although
at very high spatial resolution (5 cm to 40 cm). Foreseen data
fusion system is aimed to spatial relations. The main efforts
were allocated to development of the airborne acquisition
system and ground control station. This part was realised
very successfully and ARC as a system provided excellent
automatic aerial acquisition system. Through Trials was
collected significant amount of images for approximately 2 to
3 km°, that will enable further research of the mined scene.
Extraction of the features from images is not at needed level
of maturity needed for the minefield detection and suspected
area reduction. The project will finish at the end of year 2003
and further status will be known soon.
The spin-off of ARC, multisensor system that uses helicopter
Bell-206 as platform, has operational capacity 3 h per flight,
approved possibility of two flights per day. For flight
guidance a man is included in the loop, while the data
acquisition is digital and fully automatic. Enables mapping at
heights 130 m and more above terrain. Imaging channels
(three visible and one near infra red) can use one of three
optical objectives, two objectives for thermal infrared and up
to 99 channels for the hiper spectral airborne measurements
in visible and near infra red wavelengths. The system is fully
digital, interoperable with GIS system which is based on
MapInfo software. It is available and can be used for
purposes other than humanitarian demining.
Conclusions
A humanitarian mine action, the system for action against the
contamination by landmines should solve a very severe
problem of many undeveloped and developing countries.
Although mine contamination has minor magnitude in
developed countries, the humanitarian mine action had
significant impact on the transfer of the advanced
technologies and of know-how, particularly in the domain of
airborne multisensor remote sensing
Refere
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