How Well Do We UnderstandEarth Observation Electro-optical

Sensor Parameters ?George Joseph, ISRO, India

President, ISPRS Commission-I (1996-2000)

Stan Morain, EDAC, USAPresident ISPRS Commission-I (2000-

2004)

Spatial ResolutionInstantaneous 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 ResolutionParameters Sensor #

1Sensor #

2

Sat Radiance (mw/cm2/strd/μm)

20 35

Quantization 7 8Radiometric Sampling Interval

0.16 0.14

System S/N at SR 120 150NEΔρ .17 .23

Radiometric ResolutionTM Band

Moment FWHM

λc Δλ λc Δλ

1 486 71.5 485 66.1

2 571 88.7 569 80.6

3 660 77.1 659 68.7

4 839 134.9 841 129.1

5 1678 227 1676

216.9

7 2217 269 2272

250.2

Parameter SummaryIGFOV 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