ISO/TS 19159-3:2018

Geographic information — Calibration and validation of remote sensing imagery sensors and data — Part 3: SAR/InSAR

This document defines the calibration of SAR/InSAR sensors and validation of SAR/InSAR calibration information. This document addresses earth based remote sensing. The specified sensors include airborne and spaceborne SAR/InSAR sensors. This document also addresses the metadata related to calibration and validation.

Information géographique — Calibration et validation de capteurs de télédétection — Partie 3: SAR/InSAR

General Information

• Status: Published
• Publication Date: 06-May-2018
• ICS: 35.240.70 - IT applications in science
• Technical Committee: ISO/TC 211 - Geographic information/Geomatics
• Drafting Committee: ISO/TC 211/WG 6 - Imagery
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 06-Sep-2021

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 19159-3
First edition
2018-05
Geographic information — Calibration
and validation of remote sensing
imagery sensors and data —
Part 3:
SAR/InSAR
Information géographique — Calibration et validation de capteurs de
télédétection —
Partie 3: SAR/InSAR
Reference number
ISO/TS 19159-3:2018(E)
©
ISO 2018

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ISO/TS 19159-3:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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ISO/TS 19159-3:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, abbreviated terms and conventions . 8
4.1 Symbols . 8
4.2 Abbreviated terms .10
4.3 Conventions .10
5 Conformance .11
6 General SAR sensor calibration model .11
6.1 Introduction .11
6.2 Top-level model .12
6.3 Radar system .14
6.4 Antenna system .15
6.5 Antenna phase centre .16
6.6 SAR signal processing .17
6.7 Atmospheric propagation and earth motion .18
6.8 SAR calibration field .20
6.8.1 Introduction .20
6.8.2 CA_SARCalibrationField .22
6.8.3 CA_SARCalibrationNaturalField .22
6.8.4 CA_SARCalibrationManmadeField .22
6.8.5 CA_SARCalibrationEquipment .22
6.8.6 CA_CornerReflectorAndTransponder .22
6.8.7 CA_GroundReceiver .23
6.8.8 CA_ScatteringMatrix .23
6.9 SAR validation .23
6.10 SAR Requirement .24
7 InSAR sensor calibration model .24
7.1 General .24
7.2 CA_InSARSensor.25
7.3 InSAR Requirement .27
8 PolSAR sensor calibration model .27
8.1 General .27
8.2 CA_PolSARSensor .28
8.3 PolSAR requirement .29
Annex A (normative) Abstract test suite .30
Annex B (normative) Data dictionary .31
Annex C (informative) SAR geometric calibration use case .46
Annex D (informative) SAR radiometric calibration use case .50
Bibliography .53
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ISO/TS 19159-3:2018(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 211, Geographic information/Geomatics.
A list of all parts in the ISO 19159 series can be found on the ISO website.
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ISO/TS 19159-3:2018(E)

Introduction
Imaging sensors are one of the major data sources for geographic information.
The image data captures spatial and spectral measurements and has numerous applications ranging
from road/town planning to geological mapping. Typical spatial outcomes of the production process
are vector maps, digital elevation models, and 3-dimensional city models.
In each case the quality of the end products fully depends on the quality of the measuring instruments
that have originally sensed the data. The quality of measuring instruments is determined and
documented by calibration.
Calibration is often a costly and time consuming process. Therefore, a number of different strategies
are in place that combine longer time intervals between subsequent calibrations with simplified
intermediate calibration procedures that bridge the time gap and still guarantee a traceable level of
quality.
This document standardizes the calibration of remote sensing imagery sensors and the validation of the
calibration information and procedures. It does not address the validation of the data and the derived
products.
Many types of imagery sensors exist for remote sensing tasks. Apart from the different technologies the
need for a standardization of the various sensor types has a different priority. In order to meet those
requirements ISO/TS 19159 has been split into several parts. ISO/TS 19159-1 addresses the optical
sensors. ISO/TS 19159-2 addresses the airborne lidar (light detection and ranging) sensors. ISO/
TS 19159-3 (this document) covers synthetic aperture radar (SAR) and interferometric SAR (InSAR).
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TECHNICAL SPECIFICATION ISO/TS 19159-3:2018(E)
Geographic information — Calibration and validation of
remote sensing imagery sensors and data —
Part 3:
SAR/InSAR
1 Scope
This document defines the calibration of SAR/InSAR sensors and validation of SAR/InSAR calibration
information.
This document addresses earth based remote sensing. The specified sensors include airborne and
spaceborne SAR/InSAR sensors.
This document also addresses the metadata related to calibration and validation.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 19103, Geographic information — Conceptual schema language
ISO/TS 19130:2010, Geographic information — Imagery sensor models for geopositioning
ISO/TS 19130-2:2014, Geographic information — Imagery sensor models for geopositioning — Part 2: SAR,
InSAR, lidar and sonar
ISO 19157, Geographic information — Data quality
ISO/TS 19159-1:2014, Geographic information — Calibration and validation of remote sensing imagery
sensors and data — Part 1: Optical sensors
ISO/TS 19159-2, Geographic information — Calibration and validation of remote sensing imagery
sensors — Part 2: Lidar
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at http: //www .iso .org/obp
3.1
accuracy
closeness of agreement between a test result or measurement result and the true value
Note 1 to entry: In this document, the true value can be a reference value that is accepted as true.
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[SOURCE: ISO 3534-2:2006, 3.3.1, modified — NOTES 1, 2 and 3 have been deleted. New Note 1 to entry
has been added.]
3.2
antenna pattern
ratio of the electronic-field strength radiated in the direction θ to that radiated in the beam-maximum
direction
3.3
aperture reference point
ARP
3D location of the centre of the synthetic aperture
Note 1 to entry: It is usually expressed in ECEF coordinates in metres.
[SOURCE: ISO/TS 19130:2010, 4.4]
3.4
attitude
orientation of a body, described by the angles between the axes of that body’s coordinate system and
the axes of an external coordinate system
[SOURCE: ISO 19116:2004 4.2]
3.5
azimuth resolution
resolution in the cross-range direction
Note 1 to entry: This is usually measured in terms of the impulse response of the SAR sensor and processing
system. It is a function of the size of the synthetic aperture, or alternatively the dwell time (e.g. larger
aperture → longer dwell time → better resolution).
Note 2 to entry: 3 dB width of the impulse response is the normal value of measurements.
Note 3 to entry: Cross-range direction is also the same as along-track direction.
[SOURCE: ISO/TS 19130:2010, 4.7, modified — Notes 2 and 3 to entry have been added.]
3.6
backscattering coefficient
average radar cross section per unit area
Note 1 to entry: If the radar return from the illuminated area is contributed by a number of independent
scattering elements, it is described by the backscattering coefficient instead of radar cross section used for the
point target. It is calculated as:
σ
0
σ =
A
where
σ is the total radar cross section of an area A;
0
σ is a dimensionless parameter and is usually expressed in decibels (dB) as follows:
0 0
σσ=10log
dB 10
Note 2 to entry: “Backscattering coefficient” is sometimes called “normalized radar cross section”.
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3.7
calibration
process of quantitatively defining a system’s responses to known, controlled signal inputs
[SOURCE: ISO/TS 19101-2: 2008, 4.2]
3.8
calibration coefficient
ratio of SAR image pixel power to radar cross section without considering additive noise, after the
processor gain is normalized to one, and elevation antenna pattern, range and atmospheric attenuation
are all corrected
3.9
correction
compensation for an estimated systematic effect
Note 1 to entry: See ISO/IEC Guide 98-3:2008, 3.2.3, for an explanation of “systematic effect”.
Note 2 to entry: The compensation can take different forms, such as an addend or a factor, or can be deduced
from a table.
[SOURCE: ISO/IEC Guide 99:2007, 2.53]
3.10
cross-talk
any signal or circuit unintentionally affecting another signal or circuit
Note 1 to entry: For PolSAR sensor, if the transmitting channel is horizontally (H) polarized, the cross-talk
on transmitting defines the ratio of V polarization transmitting power to H polarization transmitting power,
expressed in decibels (dB). The cross-talk on receiving is similar to that on transmitting.
3.11
digital elevation model
DEM
dataset of elevation values that are assigned algorithmically to 2-dimensional coordinates
[SOURCE: ISO/TS 19101-2:2008, 4.5]
3.12
height
h, H
distance of a point from a chosen reference surface measured upward along a line perpendicular to
that surface
Note 1 to entry: A height below the reference surface will have a negative value.
Note 2 to entry: The terms elevation and height are synonyms.
[SOURCE: ISO 19111:2007, 4.29 — modified: Note 2 to entry has been added.]
3.13
incident angle
vertical angle between the line from the detected element to the sensor and the local surface normal
(tangent plane normal)
[SOURCE: ISO/TS 19130:2010, 4.57]
3.14
interferometric baseline
distance between the two antenna phase centre vectors at the time when a given scatterer is imaged
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3.15
integrated side lobe ratio
ISLR
ratio between the side lobe power and the main lobe power of the impulse response of point targets in
the radar imaging scene
Note 1 to entry: The integrated side lobe ratio (ISLR) can be obtained by integrating the power of the impulse
response over suitable regions. The ISLR is expressed as
 PP− 
 
total main
ISLR =10log
 
10
P
 
 main 
where
P is the total power;
total
P is the main lobe power.
main
Note 2 to entry: The main lobe width can be taken as α times the impulse response width (IRW), centred around
the peak, where α is a predefined constant, usually between 2 and 2,5.
3.16
interferometric synthetic aperture radar
InSAR
technique exploiting two or more SAR images to generate maps of surface deformation or digital
elevation through the differences in the phase of the waves returning to the radar
3.17
look angle
vertical angle from the platform down direction to the slant range direction, usually measured at the
aperture reference point (ARP)
Note 1 to entry: “Off-nadir angle” has the same definition as “look angle”.
[SOURCE: ISO/TS 19130-2:2014, 4.42, modified — new Note 1 to entry has replaced the original Note 1
to entry.]
3.18
metadata
information about a resource
[SOURCE: ISO 19115-1:2014, 4.10]
3.19
peak side lobe ratio
PSLR
ratio between the peak power of the largest side lobe and the peak power of the main lobe of the impulse
response of point targets in the SAR image
Note 1 to entry: The peak side lobe ratio is usually expressed in decibels (dB) and computed as follows:
 P 
 sidepeak 
PSLR =10log
 
10
P
 mainpeak 
 
where
P is the peak power of the main lobe;
mainpeak
P is the peak power of the largest side lobe
sidepeak
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3.20
polarimetric synthetic aperture radar
SAR sensor enhanced by transmitting and receiving in different combinations of polarization
Note 1 to entry: By combining multiple polarization modes, it is possible to characterize the target more clearly.
Quad-Pol SAR system both transmits and receives orthogonal (e.g. horizontal and vertical) polarizations,
which creates four polarizations of a single imaging scene. The calibration of Quad-Pol SAR is addressed in this
document.
3.21
polarization channel imbalance
bias in the estimation of the scattering matrix element ratio between coincident pixels from two
coherent data channels
Note 1 to entry: Polarization channel imbalance includes the amplitude imbalance and phase imbalance.
3.22
pulse repetition frequency
number of times the system (e.g. LIDAR) emits pulses over a given time period, usually stated in
kilohertz (kHz)
[SOURCE: ISO/TS 19130-2:2014, 4.53]
3.23
radar cross section
measure of the capability of the object to scatter the transmitted radar power
Note 1 to entry: Radar cross section is calculated as
2
E
2 s
σ = lim 4πR
2
R→∞
E
i
where
σ is the radar cross section;
E is the electric-field strength of the incident wave;
i
E is the electric-field strength of the scattered wave at the radar with a distance R away from the target.
s
Note 2 to entry: Radar cross section has the dimensions of area, with the unit of square metres. Usually, it is
expressed in the form of a logarithm with the unit of dBsm as follows:
σσ=10log
dBsm 10
3.24
range
distance between the antenna and a distant object, synonymous with slant range
[SOURCE: ISO/TS 19130-2:2014, 4.54]
3.25
range bin
group of radar returns that all have the same range
[SOURCE: ISO/TS 19130:2010, 4.69]
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3.26
range direction
slant range direction
direction of the range vector
[SOURCE: ISO/TS 19130:2010, 4.70]
3.27
range resolution
spatial resolution in the range direction
Note 1 to entry: For a SAR sensor, it is usually measured in terms of the impulse response of the sensor and
processing system. It is a function of the bandwidth of the pulse.
Note 2 to entry: 3 dB width of the impulse response is the normal value of measurements.
[SOURCE: ISO/TS 19130:2010, 4.71 — modified: Added Note 2 to entry.]
3.28
remote sensing
collection and interpretation of information about an object without being in physical contact with
the object
[SOURCE: ISO/TS 19101-2:2008, 4.33]
3.29
resolution (of imagery)
smallest distance between two uniformly illuminated objects that can be separately resolved in an image
Note 1 to entry: This definition refers to the spatial resolution.
Note 2 to entry: In the general case, the resolution determines the possibility to distinguish between neighbouring
features (objects).
Note 3 to entry: Resolution can also refer to the spectral and the temporal resolution.
[SOURCE: ISO/TS 19130-2:2014, 4.61 — modified: Added Notes 1, 2 and 3 to entry.]
3.30
scattering matrix
matrix characterizing the scattering process at the target of interest for polarimetric SAR
Note 1 to entry: Scattering matrix is defined by
s i
   
jkR
E E
S S 
e HH HV
H H
   
=  
    
s i
R
S S
   
E VH VV E
 
 V   V 
where

 
S S
 
HH HV
is the scattering matrix;
 
S S
 VH VV 
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i
 
E
H
 
is the electronic field vector of the wave incident on the scatterer;
 
i
 
E
 V 

s
 
E
H
 
is the electronic field vector of the scattered wave;
 
s
 
E
 V 
k is the wavenumber of the illuminating wave;
R is the distance between the target and the radar antenna.
3.31
sensor
element of a measuring system that is directly affected by a phenomenon, body, or substance carrying
a quantity to be measured
Note 1 to entry: Active or passive sensors exist. Often two or more sensors are combined to a measuring system.
[SOURCE: ISO/IEC Guide 99:2007, 3.8 — modified: The EXAMPLE and NOTE were replaced by Note 1
to entry.]
3.32
uncertainty
parameter, associated with the result of measurement, that characterizes the dispersion of values that
could reasonably be attributed to the measurand
Note 1 to entry: The parameter may be, for example, a standard deviation (or a given multiple of it), or the half-
width of an interval having a stated level of confidence.
Note 2 to entry: Uncertainty of measurement comprises, in general, many components. Some of these
components may be evaluated from the statistical distribution of the results of series of measurements and can
be characterized by experimental standard deviations. The other components, which can also be characterized
by standard deviations, are evaluated from assumed probability distributions based on experience or other
information.
Note 3 to entry: It is understood that the result of the measurement is the best estimate of the value of the
measurand, and that all components of uncertainty, including those arising from systematic effects, such as
components associated with corrections and reference standards, contribute to the dispersion.
Note 4 to entry: When the quality of accuracy or precision of measured values, such as coordinates, is to be
characterized quantitatively, the quality parameter is an estimate of the uncertainty of the measurement results.
Because accuracy is a qualitative concept, one should not use it quantitatively, that is associate numbers with it;
numbers should be associated with measures of uncertainty instead.
Note 5 to entry: Measurement uncertainty includes components arising from systematic effects, such as
components associated with corrections and the assigned quantity values of measurement standards, as well
as the definitional uncertainty. Sometimes estimated systematic effects are not corrected for but, instead,
associated measurement uncertainty components are incorporated.
Note 6 to entry: The parameter may be, for example, a standard deviation called standard measurement
uncertainty (or a specified multiple of it), or the half-width of an interval, having a stated coverage probability.
Note 7 to entry: Measurement uncertainty comprises, in general, many components. Some of these may be
evaluated by Type A evaluation of measurement uncertainty from the statistical distribution of the quantity
values from series of measurements and can be characterized by standard deviations. The other components,
which may be evaluated by Type B evaluation of measurement uncertainty, can also be characterized by standard
deviations, evaluated from probability density functions based on experience or other information.
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Note 8 to entry: In general, for a given set of information, it is understood that the measurement uncertainty
is associated with a stated quality value attributed to the measurand. A modification of this value results in a
modification of the associated uncertainty.
[SOURCE: ISO 19116:2004, 4.26 modified: Added Notes 1, 2, 3, 5, 6, 7 and 8 to entry.]
3.33
validation
process of assessing, by independent means, the quality of the data products derived from the
system outputs
Note 1 to entry: In this document, the term validation is used in a limited sense and only relates to the validation
of calibration data in order to control their change over time.
[SOURCE: ISO/TS 19101-2:2008, 4.41]
4 Symbols, abbreviated terms and conventions
In this document, conceptual schemas are presented in the Unified Modelling Language (UML).
ISO 19103 conceptual schema language presents the specific profile of UML used here.
4.1 Symbols
A area of the ground resolution cell
B length of the interferometric baseline vector
f doppler centroid frequency
d
f sampling frequency
s
f amplitude and phase imbalance between the H and V channels on receive
1
f amplitude and phase imbalance between the H and V channels on transmit
2
G imaging processor gain
p
G gain in the radar receiver
r
transmit antenna gain in the maximum-gain direction
A
G
t
receive antenna gain in the maximum-gain direction
A
G
r
A receive antenna elevation pattern which is normalized to unit gain in the maximum-gain direction
g ()θ
r
A transmit antenna elevation pattern which is normalized to unit gain in the maximum-gain
g ()θ
t
direction
H height of the antenna relative to the reference plane
h height of the target relative to the reference plane
K calibration coefficient
c
K overal
...