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ax 15m
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Models
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Nadir -21.4? indiined
f = 220 mm
f= 237 mm
Nadir
f= 237 mm f= 220 mm
f= 660 mm
+ 21.4° indined
Fig. 3: MOMS-02/2P optical concept
Merging of panchromatic high resolution (5 m) with
multispectral (15 m) proved to gain optimal result for thematic
evaluation and allowed to resolve spectral signatures in the
mix-pixel domain of the lower resolving multispectral pixels
for targets with small scaled surface pattern.
From a technical point of view MOMS-02/2P is today the most
advanced sensor in optical remote sensing due to the
combination of high resolution stereo and multispectral data.
The definition of the four spectral bands of MOMS-02/2P
allows more seperability, especially for vegetation in
comparison with other satellite sensors. The high redundancy
between the green and red bands, as it occurs with TM, SPOT
HRV and IRS 1C could be avoided. On the other side the
Indian Remote Sensing satellite IRS 1C, which was launched
in December 1995, meets very good performances concerning
the resolution (Fig. 1).
The definition of the width and location of the spectral bands
of the MOMS camera is based on spectral signatures of
relevant objects, mainly vegetation and Fe-bearing rocks and
soils. The definition of the panchromatic band was based on
the differences of apparent albedo of soils versus vegetation
due to the steep increase of reflectance at the "red edge" of
vegetation.
In the following the spectral characteristics of the multispectral
and panchromatic bands are summerized (see Figure 4). Band
1 covers the blue absorption of vegetation and allows good
penetration in water bodies. Additionally it includes the right
wing of the charge transfer band for Fe-bearing rocks and soils.
Band 2 is centred on the "green peak" of vegetation. This
position allows to avoid the high correlation between the green
and the red bands. Band 3, only 32 nm wide, lies exactly in the
principal absorption of chlorophyll-a in the red wavelength
region. This enables the acquisition of precise reflectance
values at the "red edge", an important indicator for the
detection of vegetation stress. Band 4 was defined on the
infrared plateau of vegetation between two significant water
absorption bands. This position guarantees exact reflectance
values for the maximum infrared reflectance of vegetation.
This band is also centred for the charge transfer absorption of
iron.
The panchromatic high resolution and stereo bands (Fig 4) are
defined to get most contrast between albedo of vegetation and
of non vegetated targets (rocks, soils and sealed areas). The
short-wave end of the panchromatic band is placed to avoid
most of the noise and lowpass characteristics introduced by
atmospheric scattering, but also allows some penetration of
water bodies. The long wave edge was determined to enclose
the steep raise of vegetation reflectance at the "red edge".
0.5% 8 7]
04 —
0.3 : -]
W/m: nm
Qt -
00 —l
MOMS-02/2P
Panchromatic
MOMS-02/2P
Multispectral
0.7
Wavelength[ m ]
Fig. 4: Position and Width of the MOMS-02/2P spectral and panchromatic bands
23
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996
