Slide 1

Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 1 THE VEGA 2000 data set description of data properties (draft) Compiled by E. Bartholom, JRC Ispra Slide 2 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 2 SOURCES of INFORMATION Slide 3 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 3 Main sources of Information The VEGETATION portal : http://www.spot-vegetation.com The VEGETATION web site at CNES: http://vegetation.cnes.fr the Users Guide: http://www.spotimage.fr/data/images/vege/VEGETAT/book_1/e_frame.htm Henry & al 2000: VEGETATION image performances, (Belgirate) Passot 2000: VEGETATION image processing methods in the CTIV (Belgirate) Saint 1998: the VEGETATION Programme Slide 4 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 4 Technical description of the system VEGETATION homepage at CNES: http://vegetation.cnes.fr:8080/ Slide 5 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 5 The users manual On-line: http://www.spotimage.fr/data/images/vege/VEGETAT/book_1/e_frame.htm stand-alone downloadable version: http://vegetation.cnes.fr:8080/system/content.html#perfos Slide 6 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 6 GENERAL DESCRIPTION Slide 7 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 7 VEGETATION onboard SPOT 4 Slide 8 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 8 The VEGETATION instrument IMAGE SPECTRAL BANDS :Blue - Red - NIR - SWIR (Red, NIR and SWIR identical to HRVIR ones) CODING : 10 bits OPTICS :telecentric lenses F.O.V. :101 (ground swath = 2250 km) DETECTION :CCD line array RESOLUTION :1.165 X 1.165 km Slide 9 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 9 Radiometry: specs & calibration Slide 10 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 10 Main specs of the VEGETATION system - radiometry Four spectral bands Blue0.43 - 0.47 mNear InfraRed0.78 - 0.89 m Red0.61 - 0.68 mShortWave InfraRed1.58 - 1.75 m G. Saint, 1998 Slide 11 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 11 Main specs of the VEGETATION system - radiometry Calibration interband and multitemporal : better than 3% absolute : better than 5% through : * on-board calibration device to measure evolution with time *calibration campaigns Henry & al, 2000 - Belgirate Slide 12 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 12 Calibration methods Pre-flight measurements (absolute) On-board calibration lamp (multitemporal and multi-angular) Vicarious calibration over test sites (absolute) Calibration over the Rayleigh scattering (absolute) Calibration over desert sites (multitemporal and multi-angular) Calibration over the sun glint (interband) Calibration over clouds (interband) Calibration over snowy sites (multi-angular) VGT/HRVIR intercalibration using simultaneous viewing (Henry & al., Belgirate, 2000) Slide 13 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 13 Evolution of sensor sensitivity Henry & al, 2000 - Belgirate Slide 14 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 14 Sensor calibration: an example Henry & al, 2000 - Belgirate Slide 15 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 15 Sensor calibration: overall conclusions Absolute calibration : B0 : 4% - B2 : 4% - B3 : 5% - SWIR : ? Multitemporal calibration : better than 2% Interband calibration : B2/B3 : 2% - B2/B0 : 3% - B2/SWIR : ? Intercalibration with HRVIR B2 : 3% - B3 : 2% - SWIR : 2% Henry & al, 2000 - Belgirate Slide 16 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 16 The MIR sensors Brazil - 23 May 99 Blue/NIR/SWIR SWIR defective detectors Henry & al, 2000 - Belgirate Slide 17 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 17 The MIR sensors InGaAs CCDs are sensitive to protons (irradiation tests carried out in 1999) Radiation effects: detector dark current increases and becomes unstable Henry & al, 2000 - Belgirate Slide 18 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 18 Instrument resolution Slide 19 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 19 Main specs of the VEGETATION system - reolution Spatial resolution 1km in the entire field of view Off nadir observations up to 50 Slide 20 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 20 Stable across-swath ground resolution G. Saint, 1998 Slide 21 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 21 Spatial resolution: pre-flight MTF measurement http://vegetation.cnes.fr:8080/system/mtf.htm Slide 22 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 22 Spatial resolution: in-flight FTM measurement MTF estimation using simultaneous HRVIR image as reference: Very good consistency with pre-flight measurements Henry & al, 2000 - Belgirate Slide 23 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 23 Actual effect of angular viewing on resolution Niger Delta, Dec 1, 1999: close to nadir Dec 3, 1999: close to swath edge Slide 24 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 24 Product geometry Slide 25 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 25 Main specs of the VEGETATION system - geometry Distorsions : multispectral < 0.1 km multitemporal < 0.3 km absolute location ~ 0.5 km registration with HRVIR < 0.3km Slide 26 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 26 The VEGETATION geometric correction (1) A) Straight geometrical modelling that takes into account the satellite location computed from an orbit bulletin (MADRAS) or from real time on board navigator (DORIS), attitude movements computed from the gyrometers data instrument geometrical characteristics, (measured before launch, and recalibrated in orbit): the payload positioning on SPOT4 the 4 cameras positioning on the payload the pixel viewing directions, taking into account the lenses distorsion (see next slide), specific for each camera qGeometrical modelling is made for the B3 band qOther bands pixels are located by difference to B3 (dl,dp) Passot, 2000 - Belgirate Slide 27 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 27 The VEGETATION geometric correction (2) B) Manual and assisted GCP pointing (from March 99) to fix the absolute satellite attitude error From a 3650 GCPs data base built from VEGETATION image chips previously pinpointed with SPOT HRV images. Seasonal effects are taken into account Attended operations : selection of 10 to 20 GCPs per orbit, chosen on non cloudy locations or propagation to the next orbit of the computed bias Passot, 2000 - Belgirate Slide 28 Space Applications Institute Global Vegetation Monitoring Unit The VEGA 2000 Data set - main properties E. bartholom, GLC 2000 Workshop, Ispra 29-30 Nov 2000 28 Consequence on temporal superimposition Observed location of AVHRR pixels in a time series, after D. Meyer, IJRS Registrations Multispectral :