View source for ISO/TS 19130:2010 Geographic information - Imagery sensor models for geopositioning

==Overview==
{| class="wikitable"
| Full name
| [http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=51789 ISO/TS 19130:2010, Geographic information – Imagery sensor models for geopositioning]
|-
| Version
| Edition 1
|-
| Amendments
| None
|-
| Corrigenda
| None
|-
| Published by
| ISO/TC 211
|-
| Languages
| English
|-
| Online overview
| Not available yet
|-
| Type of standard
| ISO Technical Specification <br/> Meta level
|-
| Related standard(s)
| [http://wiki.icaci.org/index.php?title=Metadata ISO 19115:2003, Geographic information – Metadata] <br/> [http://wiki.icaci.org/index.php?title=Metadata_%E2%80%93_Part_2:_Extensions_for_imagery_and_gridded_data ISO 19115-2:2009, Geographic information – Metadata – Part 2: Extensions for imagery and gridded data] <br/> ISO 19123:2005, Geographic information – Schema for coverage geometry and functions <br/> [http://wiki.icaci.org/index.php?title=Quality_assurance_of_data_supply ISO/TS 19138:2006, Geographic information – Data quality measures, which has been replaced by ISO/TC 19158:2012, Geographic information – Quality assurance of data supply]
|-
| Application
| The technical specification defines sensor models and geopositioning metadata to support interoperability of imaging data between applications and to facilitate exchange of imaging data.
|-
| Correspondence Model
| Correspondence Model <br/> Physical Model – Synthetic Aperture Radar <br/> Physical Model – Electro-optical <br/> True Replacement Model <br/> Ground Control Point collection
|-
| Fundamental geospatial dataset
| Category: Base geography <br/> Data Theme: Rectified imagery
|}

==Scope==
ISO/TS 19130:2010 identifies the information required to determine the relationship between the position of a remotely sensed pixel in image coordinates and its geoposition. It supports exploitation of remotely sensed images. It defines the metadata to be distributed with the image to enable user determination of geographic position from the observations.

ISO/TS 19130:2010 specifies several ways in which information in support of geopositioning may be provided.

#It may be provided as a sensor description with the associated physical and geometric information necessary to rigorously construct a Physical Sensor Model. For the case where precise geoposition information is needed, ISO/TS 19130:2010 identifies the mathematical formulae for rigorously constructing Physical Sensor Models that relate two-dimensional image space to three-dimensional ground space and the calculation of the associated propagated errors. ISO/TS 19130:2010 provides detailed information for three types of passive electro-optical/infrared (IR) sensors (frame, pushbroom and whiskbroom) and for an active microwave sensing system [Synthetic Aperture Radar (SAR)]. It provides a framework by which these sensor models can be extended to other sensor types.
#It may be provided as a True Replacement Model, using functions whose coefficients are based on a Physical Sensor Model so that they provide information for precise geopositioning, including the calculation of errors, as precisely as the Physical Sensor Model they replace.
#It may be provided as a Correspondence Model that provides a functional fitting based on observed relationships between the geopositions of a set of ground control points and their image coordinates.
#It may be provided as a set of ground control points that can be used to develop a Correspondence Model or to refine a Physical Sensor Model or True Replacement Model.

ISO/TS 19130:2010 does not specify either how users derive geoposition data or the format or content of the data the users generate.

==Implementation benefits==
Vast amounts of remotely sensed imaging data are collected through a variety of sensors. In order to use this data in geo-spatial applications it needs to be geopositioned, i.e. image coordinates have to be converted to coordinates relative to the Earth. Due to the diversity in sensor types and the lack of a common sensor model, the metadata required for geopositioning differs from one imaging product to another.

ISO/TS 19130:2010 specifies standardized sensor models and geopositioning metadata to support interoperability of imaging data between applications and to facilitate exchange of imaging data. For example, the standard enables the development of software products for imaging data from multiple data producers and/or a variety of sensors.

==Implementation guidelines==
Image geopositioning refers to the process of determining the coordinates of a feature relative to the Earth from image coordinates. ISO/TS 19130:2010 specifies the geopositioning information required for three approaches to geopositioning:
# Image geopositioning refers to the process of determining the coordinates of a feature relative to the Earth from image coordinates. ISO/TS 19130:2010 specifies the geopositioning information required for three approaches to geopositioning:Physical Sensor Models employ a mathematical representation of the physics and geometry of the image sensing system to determine the Earth coordinates. Firstly, a sensor model for the type of sensor under consideration is constructed mathematically. Secondly, information to relate the sensing event to the ground coordinate reference system is needed to apply the model to a given image. This information can be in one of two forms: 1) accurate data about the position, attitude, and dynamics of the sensor during imaging; or 2) ground control information such as a set of Global Navigation Satellite System (GNSS)- determined ground control points (GCPs).
#In True Replacement Models the equations to describe the sensor and its relationship to the Earth coordinate reference system are replaced with a set of equations that directly describe the relationship between the image coordinates and the Earth coordinates.
#In Correspondence Models a set of ground control points (Earth coordinates) and their corresponding image coordinates are identified and used to derive the Earth coordinates of other image coordinates. Correspondence Models are widely used but less rigorous than the other two models.

Geolocating refers to the geopositioning of an object using a Physical Sensor Model or a True Replacement Model. Georeferencing refers to geopositioning through correspondence modelling.

ISO/TS 19130:2010 specifies a conformance class for each method of providing geopositioning information. The requirements for each class are indicated in the following table. Conditional requirements are indicated with a ‘C’. For example, the geopositioning metadata for an image conforms to the Correspondence Model if the metadata meets the requirements specified in ISO/TS 19130:2010 for geopositioning information, GCP collection, GCP repository, functional fitting and the Correspondence Model. An overview of the geopositioning metadata requirements is provided in the remainder of this section. Refer to ISO/TS 19130:2010 for UML model diagrams and a data dictionary that describe these requirements in detail. The specification also includes extensive informative text to explain geopositioning and the three different approaches to geopositioning.

'''Overview of conformance classes and requirements in ISO/TS 19130:2010'''
{| class="wikitable"
| rowspan="2" | Requirement <BR/> Conformance class
| rowspan="2" | <BR/>Geopositioning information
| colspan="2" style="text-align: center;" | GCPs
| colspan="5" style="text-align: center;" | Physical Sensor Model
| rowspan="2" | Functional fitting
| rowspan="2" | True Replacement Model
| rowspan="2" | Correspondence Model
|-
| GCP collection
| GCP repository
| Sensor model completeness
| Platforminformation
| Sensorinformation
| Optics
| SAR
|-
| Correspondence Model
| style="text-align: center;" | X
| style="text-align: center;" | X
| style="text-align: center;" | X
| 
| 
| 
| 
| 
| style="text-align: center;" | X
| 
| style="text-align: center;" | X
|-
| Physical Sensor Model ? SAR
| style="text-align: center;" | X
| 
| 
| style="text-align: center;" | X
| style="text-align: center;" | X
| style="text-align: center;" | X
| 
| style="text-align: center;" | X
| 
| 
| 
|-
| Physical Sensor Model?Electro-optical
| style="text-align: center;" | X
| 
| 
| style="text-align: center;" | X
| style="text-align: center;" | X
| style="text-align: center;" | X
| style="text-align: center;" | X
| 
| 
| 
| 
|-
| True Replacement Model
| style="text-align: center;" | X
| 
| 
| 
| 
| 
| 
| 
| style="text-align: center;" | X
| style="text-align: center;" | X
| 
|-
| GCP collection
| style="text-align: center;" | X
| style="text-align: center;" | X
| style="text-align: center;" | X
| style="text-align: center;" | C
| style="text-align: center;" | C
| style="text-align: center;" | C
| style="text-align: center;" | C
| style="text-align: center;" | C
| style="text-align: center;" | C
| style="text-align: center;" | C
| style="text-align: center;" | C
|}

Geopositioning information shall consist of sensor model information and a set ground control points, where applicable. Optionally, quality information may be provided together with the set of ground control points to allow the generation of a fitting function in the Correspondence Model.

A GCP collection consists of one or more GCPs and shall have an identifier, a name and an attribute to specify the coordinate reference system of its GCPs. A GCP shall have at least two horizontal coordinates (X, Y) and an optional vertical coordinate (Z). A GCP is specified either in correspondence to image coordinates or as a description that allows a user to identify the GCP in the image. It is possible to specify the GCP collection as a grid (as opposed to a one-dimensional list).

A GCP repository is a library of GCP collections, which may be used to lookup GCP information if such information is not provided with the image itself. Access to the repository may be restricted.

The Physical Sensor Model requirement specifies the content to be included in the description of a Physical Sensor Model, amongst others, internal sensor parameters (e.g. focal length, principal point offset, pixel size, distortion coefficients), external sensor/platform parameters (e.g. sensor location, sensor orientation, collection platform velocity), the ground-to-image function, the reverse image-to-ground function, error propagation and adjustable model parameters. Quality information for Physical Sensor Models shall be provided using the appropriate quality measures specified in ISO/TS 19138:2006 (replaced by ISO 19158:2012).

The functional fitting requirement describes the information to be provided if a functional fit between image and geographic coordinates is used to geoposition the image. The function may be based on a Physical Sensor Model, as in the case of a True Replacement Model, or it may be a simple Correspondence Model based upon ground control points. The function may be a single polynomial applicable to the entire image or it may be a set of polynomials, each applicable to a separate partition. The fit may also be derived by interpolating between points in a grid where both the grid and geographic coordinates are known. A function produced by interpolation cannot be expressed in a simple analytic form over the entire image; its first derivative is discontinuous at grid cell boundaries.

The True Replacement Model requirement specifies the content to be included in the description of a True Replacement Model, amongst others, the region of validity, accuracy, information about the fitting function and geolocation information.

The Correspondence Model requirement specifies the content to be included in the description of a Correspondence Model, amongst others, the GCP collection, the region of validity and information about the fitting function.