Spectral bands - Resolution - Swath

Spectral bands for Earth observation applications are selected on the basis of: · spectral response-that is, the specific nature of signals reflected or emitted across a range of wavelengths-of features of interest, for example land surfaces, vegetation, deserts, snow, moisture and urban areas
· atmospheric transparency and transmission stability, which can only be sufficiently ensured within certain spectral "windows"

The bands on SPOT 5 in the visible and short-wave infrared portions of the spectrum are identical to those on SPOT 4:
· panchromatic (wide band): 0.49 -0.69 µm
· visible B0: 0.43 to 0.47 µm (for VEGETATION only)
· visible B1: 0.50 to 0.59 µm
· visible B2: 0.61 to 0.68 µm
· visible B3: 0.78 to 0.89 µm
· short-wave infrared (SWIR): 1.58 to 1.75 µm

The new HRS instrument acquires images in the panchromatic band only.

Spectral band	HRG	VEGETATION	HRS
PA 0.49 -0.69 µm	2.5* ou 5 m	-	10 m
B0 0.43 - 0.47 µm		1 km	-
B1 0.49 - 0.61 µm	10 m	-	-
B2 0.61 - 0.68 µm	10 m	1 km	-
B3 0.78 - 0.89 µm	10 m	1 km	-
SWIR 1.58 - 1.75 µm	20 m	1 km	-
Field of view	60 km	2250 km	120 km

* 2.5 metres using SPOT 5's unique new Supermode sampling concept.

HRG and HRS swathes

Each HRG instrument has a field of view of 4°, meaning that it can observe a swath of 60 kilometres on the ground, and can be pointed off-vertical 27° both ways for oblique viewing. Like on SPOT 4, the two instruments generally operate independently to observe separate targets, but they can also view in tandem to cover a 120-kilometre swath in a single pass.

The HRG instruments' oblique viewing capability means that SPOT 5, like its predecessors, can acquire imagery of any point on the globe within less than five days, or even in less than three days at temperate latitudes.

HRG imaging swath and oblique viewing capability

 

The field of view of each of the HRS instrument's cameras is 8°, meaning that it observes a swath of 120 kilometres centred on the satellite ground track. The front camera points 20° ahead of the nadir and the rear camera 20° behind. The maximum scene length in stereo imaging mode is thus 600 kilometres.

HRS field of view

 

HRG-HRS imaging sequence: video (1,11 Mb)
The two instruments view independently (yellow: front HRS camera; ochre: rear HRS camera; green: HRG 1; red: HRG 2).

HRG imaging sequence: video (419 kb)
HRG1 and HRG2 view in tandem to cover a ground swath of 120 kilometres.

 

 

VEGETATION swath

The VEGETATION instrument's wide field of view results in a ground swath of 2,250 kilometres, giving it the ability to cover almost all the globe's land surfaces every day. Equatorial zones below 30° latitude are covered four days out of five. Zones above 30° latitude are covered at least twice daily.

VEGETATION Field of view

7 days of VEGETATION imagery (animation)

The instrument covers almost the entire globe every day, with a field of view resulting in a ground swath of 2,250 kilometres. Equatorial zones below 30° latitude are covered four days out of five. Zones above 30° latitude are covered at least twice daily.