How Well Do We Understand
Earth Observation Electro-optical
Sensor Parameters ?
George Joseph, ISRO, India
President, ISPRS Commission-I (1996-2000)
Stan Morain, EDAC, USA
President ISPRS Commission-I (2000-2004)
Spatial Resolution
Instantaneous Geometric Field-of-View (IGFOV)
The geometric size of the image projected by the detector on the
ground through the optical system—”pixel footprint”
Radiometrically Accurate IFOV (RAIFOV)
The
resolution for which the MTF is higher than 0.95
Effective Instantaneous Field-of View (EIFOV)
The resolution corresponding to a spatial frequency (ground
resolution) for which the system MTF is 50%
Modulation Transfer Function (MTF)
The reduction in
contrast in the image compared to the contrast of the objects
imaged
Radiometric Resolution
Parameters
Sensor # 1 Sensor # 2
Sat Radiance (mw/cm2/strd/μm)
20
35
Quantization
7
8
Radiometric Sampling Interval
0.16
0.14
System S/N at SR
120
150
NEΔρ
.17
.23
Radiometric Resolution
TM Band
1
2
3
4
5
7
Moment
FWHM
λc
Δλ
λc
Δλ
486
71.5 485 66.1
571
88.7 569 80.6
660
77.1 659 68.7
839 134.9 841 129.1
1678 227 1676 216.9
2217 269 2272 250.2
Parameter Summary
IGFOV
Along, Across Trck
% out-of-band Res
Metric?
RAIFOV
Along, Across Trck
Saturation Radiance
mw/cm2/strad/μm
GSD
Along, Across Trck
Quantization
bits
Swath (TFOV)
mrad
S/N
Ru; Rt
SWR @ IGFOV
Along, Across Trck Radiometric Accurcy
Absolute; Relative
SWR @ GSD
Along, Across Trck
Data Compression
RMS error
Band-band Reg
Metric?
Polarization accuracy
Metric?
Central λ
λc
Revisit Period
0° Lat; 40° Lat
Bandwidth
Δλ
Repeat Period
° off-nadir
Carry Forward For Commission-I
2000-2004
• Identify a set of sensor parameters to
ensure maximum retrieval of information
• Make intrinsic sensor capabilities
transparent so users can make sound
choices
• Formulate standard procedures for
measuring parameters