ISO/TS 19124-1:2023

Geographic information - Calibration and validation of remote sensing data and derived products - Part 1: Fundamentals

The ISO 19124 series is focused on calibration and validation (Cal/Val) of remote sensing data, which are collected by a sensor on-board a platform in a mission, and products derived in part or whole from the data. The ISO 19124 series defines the metadata related to the calibration and validation process that has not been defined in other ISO/TC 211 International Standards. The metadata allows the data providers to provide a standardized description of the Cal/Val process they have applied to the data. It allows the data users to get the same forms of metadata from different data providers. This document addresses the overall framework and common calibration and validation processes related to Earth observation data and derived products from different types of remote sensors. Subsequent parts in the ISO 19124 series will target data from specific sensors, for example, infrared, ultraviolet/visible/near-infrared, microwave, or broadband, products derived from those data, and calibration and validation sites. Calibration addresses a geometric, radiometric, or spectral correction of the data. Validation addresses an evaluation of the quality and the accuracy of the data and the derived products.

Information géographique — Calibration et validation des données de télédetection et produits dérivés — Partie 1: Principes de base

General Information

• Status: Published
• Publication Date: 26-Apr-2023
• 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: 6060 - International Standard published
• Start Date: 27-Apr-2023
• Due Date: 05-Dec-2022
• Completion Date: 27-Apr-2023

Overview

ISO/TS 19124-1:2023 - "Geographic information - Calibration and validation of remote sensing data and derived products - Part 1: Fundamentals" provides a common framework and foundational guidance for post‑launch calibration and validation (Cal/Val) of remote sensing data and products. The Technical Specification defines the Cal/Val metadata not covered by other ISO/TC 211 standards so that data providers can describe the calibration and validation processes consistently and data users can interpret and compare Cal/Val information across missions and suppliers.

Key topics

• Scope and framework: overall Cal/Val framework for Earth observation data and derived products from a variety of sensors and platforms.
• Calibration types: geometric, radiometric and spectral calibration concepts and relationships between sensor calibration and data calibration.
• Pre-launch and post-launch Cal/Val: use of pre-launch results and structured post-launch activities (early operations, on-board calibration, intensive Cal/Val).
• Calibration reference sources: on-orbit sources and ground references, including solar diffusers, white light sources, LEDs, tuneable laser diodes, black bodies, celestial objects, and sensor‑specific references (active/passive optical, microwave, SAR).
• Calibration methods: on-orbit cross‑calibration, vicarious calibration, and sensor performance trending.
• Validation of derived products: generic validation process, quality checks, spatio‑temporal co‑location, metric calculation, maturity assessment, and validation planning across mission phases.
• Metadata and data dictionary: definition of Cal/Val metadata elements and an abstract test suite to support interoperability and standardized documentation.
• Series context: Part 1 covers fundamentals; subsequent parts address sensor‑ or product‑specific Cal/Val (e.g., infrared, UV/VIS/NIR, microwave, broadband, and validation sites).

Practical applications

• Enables consistent reporting of calibration and validation metadata, improving transparency for Earth observation data consumers (researchers, modelers, and commercial users).
• Supports quality assurance for satellite operators, instrument teams, and ground segment engineers managing radiometric/geometric corrections and on-board calibration systems.
• Facilitates cross‑mission comparisons and long‑term climate or environmental monitoring by standardizing Cal/Val descriptions and validation metrics.
• Assists data producers and service providers in meeting user expectations for data accuracy, traceability, and provenance.

Who should use this standard

• Satellite and sensor manufacturers, mission calibration teams, Earth observation data providers, QA/QC specialists, remote sensing scientists, national mapping and environmental agencies, and commercial EO analytics companies.

Related standards

• ISO 19124 series (this is Part 1 - fundamentals); subsequent parts cover sensor‑specific Cal/Val.
• ISO 19159 series (focuses on pre‑launch sensor and hardware Cal/Val).

Keywords: ISO/TS 19124-1:2023, calibration and validation, Cal/Val metadata, remote sensing data, Earth observation, radiometric calibration, geometric calibration, vicarious calibration, on‑orbit cross‑calibration, validation of derived products.

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 19124-1
First edition
2023-04
Geographic information — Calibration
and validation of remote sensing data
and derived products —
Part 1:
Fundamentals
Reference number
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.7
5 Calibration of remote sensing data .10
5.1 Introduction . 10
5.2 Relationship between the data calibration and sensor calibration . 11
5.3 General framework . 11
6 Pre-launch calibration .16
6.1 Introduction . 16
6.2 Use of pre-launch calibration results in data calibration . 16
7 Post-launch calibration .16
7.1 Goals . 16
7.2 General demands . 16
7.3 On-board calibration against known sources . 17
7.4 Early operations . 17
7.5 Intensive calibration and validation . 18
8 Calibration reference sources .18
8.1 Introduction . 18
8.2 Active optical instruments . 18
8.3 Passive optical instruments, visible and NIR, SWIR, MWIR, TIR, and FIR spectrum . 19
8.3.1 Introduction . 19
8.3.2 On-orbit calibration sources . 19
8.3.3 Solar diffusers . . . 19
8.3.4 White light sources .20
8.3.5 Light-emitting diodes (LEDs) . 20
8.3.6 Tuneable laser diodes .20
8.3.7 Black bodies .20
8.3.8 Celestial objects . 20
8.4 Active microwave instruments .23
8.4.1 Introduction . 23
8.4.2 SAR missions . 24
8.5 Passive microwave instruments . 24
8.6 Instruments with a sensitivity in other regions of the electro-magnetic spectrum . 24
8.7 Sound . . 25
8.8 Calibration and validation sites . 25
8.8.1 Introduction . 25
8.8.2 Pseudo invariant calibration/validation sites (PICS) . 25
8.8.3 Calibration and validation sites . 25
9 Calibration methods.26
9.1 Introduction . 26
9.2 On-orbit cross-calibration . 26
9.3 Vicarious calibration . 26
9.4 Sensor performance trending . 27
10 Validation of derived products .27
10.1 Validation process . 27
10.1.1 General . 27
10.1.2 Data . 27
iii
10.1.3 Quality check / Homogenization .28
10.1.4 Spatio-temporal co-location .28
10.1.5 Metric calculation .28
10.1.6 Analysis and interpretation .28
10.2 Generic validation process . 32
10.3 Data product validation . 33
10.4 Maturity of data product validation . 33
10.5 Validation planning .34
10.5.1 Phase E1 .34
10.5.2 Phase E2 / main validation phase . 35
10.5.3 Phase E2 / routine operation validation . 35
10.5.4 Phase E2 / data and algorithm evolution . 35
10.5.5 Phase F . . 35
10.6 Recommendations . 35
11 The ISO 19124 series .36
11.1 Introduction . 36
11.2 Imaging instruments .36
11.2.1 Infrared instruments .36
11.2.2 Ultraviolet, visible and near-infrared instruments . 37
11.2.3 Microwave instruments . 37
11.3 Non-imaging instruments . 37
Annex A (normative) Abstract test suite .38
Annex B (normative) Data dictionary .41
Annex C (informative) Detailed description of calibration and validation (supplementary
information for Annex B) .48
Bibliography .54
iv
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 of 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
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 19124 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
The ISO 19124 series addresses post-launch calibration and validation (Cal/Val) of remotely sensed
data and products derived from the data. This document, ISO 19124-1, provides the fundamentals and
a common framework on Cal/Val of remote-sensing data and derived products. Subsequent parts of the
ISO 19124 series deal with sensor- or product-specific Cal/Val.
NOTE In contrast to the ISO 19124 series, the ISO 19159 series focuses on the pre-launch Cal/Val process of
the sensor and hardware.
This document was drafted based on material provided by the major organizations that are active in
this field such as CEOS (international), NASA (USA), ESA (Europe), JAXA (Japan), CSIRO (Australia), and
the Chinese space agency.
In accordance with the ISO/IEC Directives, Part 2, 2018, Rules for the structure and drafting of
International Standards, in International Standards the decimal sign is a comma on the line. However,
the General Conference on Weights and Measures (Conférence Générale des Poids et Mesures) at its
meeting in 2003 passed unanimously the following resolution:
“The decimal marker shall be either a point on the line or a comma on the line.”
In practice, the choice between these alternatives depends on customary use in the language concerned.
In the technical areas of geodesy and geographic information it is customary for the decimal point
always to be used, for all languages. That practice is used throughout this document.
vi
TECHNICAL SPECIFICATION ISO/TS 19124-1:2023(E)
Geographic information — Calibration and validation of
remote sensing data and derived products —
Part 1:
Fundamentals
1 Scope
The ISO 19124 series is focused on calibration and validation (Cal/Val) of remote sensing data, which
are collected by a sensor on-board a platform in a mission, and products derived in part or whole from
the data. The ISO 19124 series defines the metadata related to the calibration and validation process
that has not been defined in other ISO/TC 211 International Standards. The metadata allows the data
providers to provide a standardized description of the Cal/Val process they have applied to the data. It
allows the data users to get the same forms of metadata from different data providers.
This document addresses the overall framework and common calibration and validation processes
related to Earth observation data and derived products from different types of remote sensors.
Subsequent parts in the ISO 19124 series will target data from specific sensors, for example, infrared,
ultraviolet/visible/near-infrared, microwave, or broadband, products derived from those data, and
calibration and validation sites.
Calibration addresses a geometric, radiometric, or spectral correction of the data. Validation addresses
an evaluation of the quality and the accuracy of the data and the derived products.
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 19157-1, Geographic information — Data quality — Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
accuracy
closeness of agreement between a test result or measurement result and the true value
[SOURCE: ISO 3534-2:2006, 3.1.1, modified — Notes to entry have been removed.]
3.2
bias
magnitude of the non-random or systematic errors of a result
Note 1 to entry: A bias can be positive or negative.
Note 2 to entry: This entry is adapted from Reference [9].
3.3
calibration
process of quantitatively defining a system’s responses to the known, controlled signal inputs
[SOURCE: ISO 19101-2:2018, 3.2]
3.4
calibration curve
expression of the relation between indication and corresponding measured quantity value
[SOURCE: ISO/IEC Guide 99:2007, 4.31, modified — Note 1 to entry has been removed.]
3.5
calibration equation
equation relating the primary measure and that of the radiometer, for example the brightness
temperature, to subsidiary measurands, such as powers, and to calibration quantities, such as standard
values
[SOURCE: ISO/TS 19159-4:2022, 3.15]
3.6
calibration parameters
information generated (or that will be generated) during the course of a calibration that quantifies and/
or describes the Earth observation (EO) sensor performance
Note 1 to entry: These parameters may be laboratory measurement, thermal vacuum (TVAC) performance plots,
or sheets (as allowed).
Note 2 to entry: This entry is adapted from Reference [12].
3.7
co-location
procedure to match the location of two or more spatial datasets
3.8
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]
3.9
cross-calibration
process of relating the measurements of one instrument to another instrument which is usually well-
calibrated, serving as a reference
Note 1 to entry: Cross-calibration of instruments operating during the same period requires careful collocation
wherein instrument outputs are compared when the instruments are viewing the same Earth scenes, at the same
times, from the same viewing angles.
[SOURCE: ISO/TS 19159-4:2022, 3.18]
3.10
derived product
product that is not directly measured by sensors but derived from direct sensor
measures by algorithms or models
3.11
detector
sensing element that generates an output signal in response to an energy input
[SOURCE: ISO 19130-1:2018, 3.18, modified — The domain has been added to the
entry and "device" has been replaced by "sensing element" at the beginning of the definition.]
3.12
emissivity
ratio of the energy radiated by an emissive surface relative to that of an ideal blackbody source at the
same temperature
Note 1 to entry: It is generally related as a function of wavelength or frequency, emissivity values range from
0 to 1.
Note 2 to entry: This entry is adapted from Reference [12].
3.13
evaluation
systematic determination of the extent to which an entity meets its specified
criteria
Note 1 to entry: The entity can be an item or activity.
[SOURCE: ISO/IEC 25001:2014, 4.1, modified — The domain and a new Note 1 to
entry have been added.]
3.14
filter
optical device that is placed in the optical path of an Earth observation (EO) sensor
to select, restrict, reject, limit or adjust an EO sensor response
Note 1 to entry: The range of desired wavelengths/frequencies to be passed by an optical filter is called the
"bandpass". This is generally defined by the cut-on and cut-off wavelengths/frequencies of the optical filter.
Note 2 to entry: The EO sensor response to the optical wavelengths/frequencies within the desired optical filter
bandpass is called the "in-band response".
Note 3 to entry: The ability of an optical filter (or optical system) to reject optical energy outside the desired
wavelengths/frequencies is referred to as "out-of-band (OOB) blocking". This can also refer to filter design
specifications regarding the ability to reject optical energy outside the desired filter bandpass.
Note 4 to entry: Undesired optical energy that passes through an optical filter (or optical system) that has a
spectral location outside the desired spectral bandpass is called " OOB leakage".
Note 5 to entry: An EO sensor’s response to OOB leakage is called the "OOB response".
Note 6 to entry: The ratio of the open-path throughput of an optical path with and without the filter is called
"transmittance". Generally expressed as a function of wavelength or optical frequency, transmittance values
range from 0 to 1, or 0 % to 100 % if expressed in percent transmittance.
Note 7 to entry: This entry is adapted from Reference [12].
3.15
irradiance
electro-magnetic radiation energy per unit area per unit time
[SOURCE: ISO/TS 19159-1:2014, 4.13, modified —Note 1 to entry has been removed.]
3.16
measure
value described using a numeric amount with a scale or using a scalar reference system
Note 1 to entry: When used as a noun, measure is a synonym for physical quantity.
[SOURCE: ISO 19136-1:2020, 3.1.41]
3.17
measurement
set of operations having the object of determining the value of a quantity
[SOURCE: ISO 19101-2:2018, 3.21]
3.18
measurement error
error of measurement
error
measured quantity value minus a reference quantity value
[SOURCE: ISO/TS 19159-1:2014, 4.18, modified — Notes to entry have been removed.]
3.19
noise
unwanted signal which can corrupt the measurement
Note 1 to entry: In most measurement scenarios, measurement noise limitations challenge measurement
objectives and are a major contributor to overall measurement uncertainty.
Note 2 to entry: Noise equivalent radiance (NER) is the entity of radiance that is most appropriate for the
description of radiant flux from an extended area source. The NER is the amount of radiant flux that produces a
signal equal to the system’s noise when viewing an extended source.
[SOURCE: ISO/TS 19159-1:2014, 4.22, modified — The original Note 1 to entry has been removed and
two new Notes to entry have been added.]
3.20
point source
source of electromagnetic radiation that is resolved in the ideal case to a single point or direction in
space
Note 1 to entry: A natural star is an ideal point source. In the laboratory on the ground, a point source is simulated
using an optical collimator.
Note 2 to entry: This entry is adapted from Reference [12].
3.21
post-launch calibration
all calibration activities that occur after a satellite-based Earth observation (EO) sensor is on-orbit
Note 1 to entry: The post-launch calibration may also be referred to as on-orbit calibration.
Note 2 to entry: The scope of the post-launch calibration varies from program to program and sensor to sensor,
and includes considerations such as mission objectives, measurement requirements, mission operations
capabilities, sensor data collection capabilities, and the ability to downlink low-level sensor response data to the
ground.
Note 3 to entry: Post-launch calibration activities are included in the calibration plan and are executed according
to the post-launch calibration procedures.
Note 4 to entry: This entry is adapted from Reference [12].
3.22
precision
measurement precision
closeness of agreement between indications or measured quantity values obtained by replicate
measurements on the same or similar objects under specified conditions
[SOURCE: ISO/TS 19159-2:2016, 4.23, modified — Notes to entry have been removed and the original
preferred term and admitted terms have been inversed.]
3.23
pre-launch calibration
sequence of measurement and characterization that takes place during and after instrument assembly
and integration, prior to launch
Note 1 to entry: Pre-launch calibration provides the best or only chance to measure calibration key data (CKD)
such as spectral response, linearity and polarization sensitivity, and also provides an important quality control
and validation function to prevent unpleasant surprises and disappointment after launch.
Note 2 to entry: Pre-launch calibration is also called ground calibration.
Note 3 to entry: This entry is adapted from Reference [12].
3.24
quality
degree to which a set of inherent characteristics of an object fulfils requirements
[SOURCE: ISO 9000:2015, 3.6.2, modified — Notes 1 and 2 to entry have been removed.]
3.25
radiance
at a point on a surface and in a given direction, the radiant intensity of an element of the surface, divided
by the area of the orthogonal projection of this element on a plane perpendicular to the given direction
[SOURCE: ISO 19101-2:2018, 3.30]
3.26
radiometric calibration
process of deriving coefficients, identifying and describing behaviours, and characterizing all aspects
of a remote sensing instrument to relate the response of the sensor to a known quantity of flux entering
the system
Note 1 to entry: A system that has undergone this process can then infer the value of an unknown quantity of flux
based on the response of the instrument.
Note 2 to entry: This entry is adapted from Reference [12].
3.27
remote sensing
collection and interpretation of information about an object without being in physical contact with the
object
[SOURCE: ISO 19101-2:2018, 3.33]
3.28
repeatability
stability of the response of a remote sensing instrument over time
Note 1 to entry: Repeatability or stability of a measurement between adjacent samples or within a single
integrated measurement interval is referred to as "short-term" repeatability. Short-term repeatability is
quantified from measurement noise with a timescale of typically seconds to minutes.
Note 2 to entry: Repeatability or stability of response from a stable input between consecutive or succeeding
integrated measurement intervals is referred to as "medium-term" repeatability. Medium-term repeatability is
typically quantified via benchmark tests that are included as part of a measurement sequence. Medium-term
repeatability sources may include on-board stimulator sources, vicarious ground sources and stellar references.
The medium-term repeatability timescale is typically minutes to hours.
Note 3 to entry: Repeatability or stability between widely separated measurement intervals is referred to as
"long-term" repeatability. Long-term repeatability is typically quantified via benchmark tests that periodically
measure constant radiometric source(s) over the life of the sensor. Long-term repeatability sources may include
on-board stimulator sources, vicarious ground sources and stellar references. The long-term repeatability
timescale is typically hours to days, up to the lifetime of the sensor.
Note 4 to entry: This entry is adapted from Reference [12].
3.29
sensor
element of a measuring system that is directly affected by a phenomenon, body, or substance carrying a
quantity to be measured
[SOURCE: ISO/IEC Guide 99:2007, 3.8, modified — The Example and Note 1 to entry have been removed.]
3.30
spectral irradiance
entity of flux that describes a point source or a source of a fixed size and distance such as the Sun when
viewed from Earth
Note 1 to entry: When irradiance includes wavelength dependence it is called spectral irradiance. Generalized
2 2
units of spectral radiance are Watts/ (cm ·μm) or Photons/sec/(cm ·μm).
Note 2 to entry: This entry is adapted from [12].
3.31
stability
ability of a measuring instrument or measuring system to maintain its metrological characteristics
constant with time
[SOURCE: ISO/TS 19159-4:2022, 3.38]
3.32
temporal stability
consistency of a linear trend
3.33
uncertainty
measurement 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: 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.
[SOURCE: ISO 19116:2019, 3.28, modified — "measurement uncertainty" has been added as an admitted
term; Note 1 to entry has been replaced with Note 2 to entry from ISO 19101-2: 2018, 3.40.]
3.34
validation
process of assessing, by independent means, the quality of the data products derived from the system
outputs
Note 1 to entry: Reference [4] defines "validation" as the process of evaluating by independent means the
accuracy of satellite-derived land products and quantifying their uncertainties by analytical comparison with
reference data.
Note 2 to entry: Reference [12] defines "validation" as the process of confirming that the specifications and
requirements set out in the design of an operation were sufficient to meet the objectives of the operation.
[SOURCE: ISO 19101-2:2018, 3.41, modified — Notes 1 and 2 to entry have been added.]
3.35
verification
provision of objective evidence that a given item fulfils specified requirements
[SOURCE: ISO/IEC Guide 99:2007, 2.44, modified — The EXAMPLEs and Notes to entry have been
removed.]
3.36
vicarious calibration
post-launch calibration of sensors that make use of natural or artificial sites on the surface of the Earth
[SOURCE: ISO/TS 19159-1:2014, 4.41]
4 Symbols and abbreviated terms
AK averaging kernel
BRDF bidirectional reflectance distribution function
Cal/Val calibration and validation
CEOS Committee on Earth Observing Satellites
CEOS WGCV Committee on Earth Observing Satellites Working Group on Calibration and Validation
DFS degree of freedom for signal
EO Earth observation
FOV field of view
FRM fiducial reference measurement
GUM Guide to the Expression of Uncertainty Measurement
InSAR interferometric SAR
IR infrared
K Kelvin
LED light-emitting diode
LEO low Earth orbit
Lidar light detection and ranging
MI mutual information
MIPAS Michelson Interferometer for Passive Atmospheric Sounding
MW microwave
MWIR mid-wave infrared
NIR near infrared (spectral region)
PDF probability density function
PICS pseudo-invariant calibration sites
PUM product user manual
RAR real aperture radar
RMS root mean square
RMSD root-mean-square deviation
RMSE root-mean-square error
SAR synthetic aperture radar
SNO simultaneous nadir overpass
SNR signal to noise ratio
SONAR sound navigation and ranging
SWIR shortwave infrared
TIR thermal infrared
TVAC thermal vacuum
UAV unmanned aerial vehicle
UV ultraviolet
VIM Vocabulary of International Metrology
VIS visible
WLS white light source
Table 1 provides the parameters and definitions used throughout this document, notably in Annex C.
Table 1 — Parameters and their definitions
Parameter Definition

x first observation vector; can be either point-like (1D), an area (2D),
or a volume (3D)

second observation vector
y
continuous geophysical field in space and time ( t : time, r : space)
θ()tr,
α
first field of a true, but unknown geophysical variable
θ
β
second field of a true, but unknown geophysical variable
θ
TTabablele 1 1 ((ccoonnttiinnueuedd))
Parameter Definition
αβ, multi-indices summarizing information on temporal and spatial
resolution/averaging
n
number of samples in both space and time
h first nonlinear mapping function, also called measurement opera-
tor
second nonlinear mapping function, also called measurement oper-
k
ator

vector of measurement errors in x
u
x

vector of measurement errors in y
u
y

vector of differences between the sampled observation and the
e
x
true, but unknown, state of the geophysical field

vector of differences between the two sample vectors
δ

vector of differences between the two fields of geophysical varia-
d
θ
bles
probability density function (PDF) of δ
f
δ
M error model M that allows the prediction of the PDF of δ
mean of δ
μ
δ
variance of δ
σ
δ
empirical estimator (denoted by the circumflex) of the mean of δ
μˆ
δ
empirical estimator (denoted by the circumflex) of the variance of
ˆ
σ
δ δ
expectation operator
E[]δ
1-dimensional function of x
f
x
1-dimensional function of y
f
y
2-dimensional function of x and y
f
xy,
x
first observation data set
y
second observation data set
covariance between the data sets x and y
σ
xy
bias
b
empirical estimator (denoted by the circumflex) of the mean of x
ˆ
μ
x
empirical estimator (denoted by the circumflex) of the mean of y
μˆ
y
is the radiance measure of pixel i. The summation covers all pixels
L
i
on the Moon, N.
median
md
median of x
p
x
median of y
p
y
R
linear (Pearson) product-moment correlation coefficient
t
unknown truth
R
ρ
Spearman’s rank correlation coefficient (nonparametric, nonlinear)
empirical estimator (denoted by the circumflex) of the variance of
ˆ
σ
x x
empirical estimator (denoted by the circumflex) of the variance of
σˆ
y y
TTabablele 1 1 ((ccoonnttiinnueuedd))
Parameter Definition
empirical estimator (denoted by the circumflex) of the covariance
σˆ
xy
between the data sets x and y
empirical estimator (denoted by the circumflex) of the covariance
σˆ
xz
between the data sets x and z
empirical estimator (denoted by the circumflex) of the covariance
σˆ
yz
between the data sets y and z
empirical estimator (denoted by the circumflex) of the variance of
σˆ
r r
x x
empirical estimator (denoted by the circumflex) of the variance of
σˆ
r r
y
y
empirical estimator (denoted by the hat symbol) of the covariance
σˆ
r
of r
xy
xy
τ
Kendall’s Tau (nonparametric, nonlinear)
number of data pairs with concordant ranksn
c
n number of pairs with discordant ranks
d
number of all possible data pairs
n
IM, I mutual information
()
t
time
c
constant value
β temporal stability, slope of a linear trend
seasonal signal with predefined periodicity
S
t
shift in the mean of the time series at time t
U
t
data noise represented by a stationary autoregressive process of
N
t
order 1
solid angle subtended by one pixel
Ω
pix
Σ additional variance
5 Calibration of remote sensing data
5.1 Introduction
Remote sensing is the science and technology for acquiring information about an object or phenomenon
without making physical contact with it. The object or phenomenon can be terrestrial or extra-
terrestrial. This document only deals with terrestrial remote sensing.
The acquisition of information is conducted by sensors which collect data. The acquired data are further
processed into information by algorithms or models. The sensors sensed an object or phenomenon
through recording the energy of electromagnetic or mechanical waves either reflected or emitted by
the object or phenomenon. Each type of sensors works on a specific range of wavelengths based on
specific physical principles. For example, passive optical sensors work on solar visible and infrared
wavelengths reflected by objects or phenomenon.
Remote sensors are usually mounted on a platform. The common platforms include satellites, aircrafts,
unmanned aerial vehicles (UAVs), ground vehicles, ships, etc. The information derived from the remotely
sensed data describes properties of the object or phenomenon, such as land surface temperature, ocean
salinity, and crop yield. Such information is widely used in applications and decision making in almost
all Earth science disciplines and socioeconomical activities.
In order for the information to be useful in the applications and decision making, the information has
to be validated against the truths and errors in the information shall be measured either quantitively
or qualitatively. To do so, the quality of remote sensing data shall be known so that the data users can
determine if the data can be used as the inputs to derive information for their applications. Due to
sensor internal and environmental noises, remotely sensed data always contain errors. Many of the
errors can be corrected and the remaining errors in data can be quantified. Such a process is called the
calibration and validation (Cal/Val) of remotely sensed data.
5.2 Relationship between the data calibration and sensor calibration
Errors in remotely sensed data come from two sources, the sensor and the sensing environment.
Therefore, to calibrate the remotely sensed data, errors from the sensor and the sensing environment
shall be quantified. Before a sensor is commissioned, the errors from the sensor can be quantified in a
laboratory environment. Such an effort is called pre-launch calibration. The ISO 19159 series addresses
the prelaunch calibration and validation of remote sensors.
After the sensor is launched, the sensor can potentially degrade due to sensor aging or exposure to
the operational environment. Therefore, the sensor’s performance needs to be monitored and sensor
calibration parameters obtained in the pre-launch calibration need to be modified continuously after
the sensor is launched. These activities constitute the post-launch sensor calibration and validation.
The post-launch sensor Cal/Val is covered by ISO 19124 series.
Another portion of errors in the remote sensing data comes from the sensing environment. For example,
data acquired by a satellite sensor for measuring the land surface radiance are contaminated by the
atmospheric radiance. Therefore, errors from the sensing environment are often time- and location-
dependant and can only be quantified after the remote-sensing data are acquired. In summary, the Cal/
Val of remote-sensing data needs the support of post-launch Cal/Val of sensors, and post-launch sensor
Cal/Val modifies the results of pre-launch sensor Cal/Val.
5.3 General framework
This subclause discusses the overall UML model of this document.
Figure 1 shows the top-level UML model of this document. CA_CalibrationValidation shall be a specified
class of MD_ContentInfo. CA_CalibrationValidation is aggregated from the CA_Methods class, which
describes the Cal/Val methods common to different types of sensors and data, and CA_RefSources class,
which describes reference sources commonly used for Cal/Val of data acquired by multiple types of
sensors. The details of CA_Methods and its subclasses are shown in Figure 2 and described in Clause 9.
The details of
...