BackForwardInstrument:  HRG 

Instrument details
Acronym HRG
Full name Haute Résolution Géométrique
Purpose High-resolution land and vegetation observation.  Digital Elevation Model (DEM)
Short description Two parallel radiometers, 5 VIS/NIR/SWIR channels, 4 multi-spectral (MS), one panchromatic (PAN) [see detailed characteristics below]
Background Evolution of HRVIR on SPOT-4
Scanning Technique Pushbroom, 6000 pixel/line (MS), 12000 pixel/line (PAN), swath 60 km ssp (117 km with two instruments), cross-track pointing capability within a range of ± 450 km.  Stereoscopic capability between successive orbits
Resolution 10 m (the three VNIR channels), 20 m (the SWIR channel), 5 m (PAN) with super-mode at 2.5 m
Coverage / Cycle Global coverage in 26 days, in daylight.  With strategic pointing, one place can be observed every 3 days.
Mass 356 kg Power 344 W Data Rate 100 Mbps

 

Providing Agency CNES
Instrument Maturity Flown on operational programme
Utilization Period: 2002-07-12 to 2015-03-27
Last update: 2017-03-28
Detailed characteristics
Central wavelength Spectral interval SNR @ specified albedo
0.545 µm 0.49 - 0.61 µm 171 @ 50 % albedo, SZA=60°
0.645 µm 0.61 - 0.68 µm 188 @ 50 % albedo, SZA=60°
0.835 µm 0.78 - 0.89 µm 202 @ 70 % albedo, SZA=60°
1.645 µm 1.58 - 1.75 µm 189 @ 50 % albedo, SZA=60°
0.59 µm (PAN) (2 shifted channels) 0.49 - 0.69 µm 149 @ 50 % albedo, SZA=60°
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Earth observation instrument
  • Passive optical radiometer or spectrometer
  • High resolution optical imager
Mission objectives
Primary mission objectives
  • Biomass
  • Fraction of vegetated land
  • Leaf Area Index (LAI)
  • Normalised Difference Vegetation Index (NDVI)
  • Vegetation type
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Tentative Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
VariableRelevance for measuring this variableOperational limitationsExplanation
Normalised Difference Vegetation Index (NDVI)2 - very highCloud sensitive.. Infrequent coverage.VIS and NIR channels
Photosynthetically Active Radiation (PAR)5 - marginalCloud sensitive.. Infrequent coverage.VIS channels, range undersampled
Sea-ice cover4 - fairCloud sensitive.. Daylight only.VIS, NIR (for contour enhancement) and SWIR (for discrimination from clouds) channels
Aerosol volcanic ash5 - marginalCloud sensitive.. Infrequent coverage.. Daylight only.VIS, NIR and SWIR channels
Aerosol volcanic ash Total Column5 - marginalCloud sensitive.. Infrequent coverage.. Daylight only.VIS, NIR and SWIR channels
Cloud cover5 - marginalInfrequent coverage.. Daylight only.VIS, NIR and SWIR channels
Cloud optical depth3 - highLow-density cloud only.. Infrequent coverage.. Daylight only.VIS, NIR and SWIR channels
Upward short-wave irradiance at TOA5 - marginalSpectral interpolation needed.. Information on BRDF needed.. Infrequent coverage.VIS, NIR and SWIR channels
Short-wave cloud reflectance4 - fairInfrequent coverage.VIS, NIR and SWIR channels. Unsuitable dynamic range (saturation)
Leaf Area Index (LAI)2 - very highCloud sensitive.. Daylight only.. Infrequent coverage.VIS, NIR and SWIR channels
Vegetation type2 - very highCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Fraction of vegetated land1 - primaryCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Biomass4 - fairCloud sensitive.. Index only.. Infrequent coverage.. Daylight only.VIS, NIR and SWIR channels. Biomass inferred from NDVI and LAI
Soil moisture at surface5 - marginalCloud sensitive.. Index only.. Infrequent coverage.. Daylight only.VIS, NIR and SWIR channels. Soil moisture inferred from differential brightness
Snow cover1 - primaryCloud sensitive.. Infrequent coverage.. Daylight only.VIS, NIR, SWIR (snow/cloud discrimination) and panchromatic (higher resolution) channels
Soil type1 - primaryCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Land cover1 - primaryCloud sensitive.. Daylight only.VIS, NIR and SWIR channels
Land surface topography5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS and panchromatic channels with cross-track steering capability for stereoscopy between images from neighbour orbits
Glacier cover3 - highCloud sensitive.. Long time for mapping.. Daylight only.VIS, NIR, SWIR and panchromatic channels for accurate boundary detection and screening ice from clouds
Glacier topography5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS and panchromatic channels with cross-track steering capability for stereoscopy between images from neighbour orbits
Ice sheet topography5 - marginalCloud sensitive.. Long time for mapping.. Daylight only.VIS and panchromatic channels with cross-track steering capability for stereoscopy between images from neighbouring orbits
Fire fractional cover2 - very highCloud sensitive.. Daylight only.VIS channels with high resolution for boundary detection