The ISO TC211 Standard Project 19130: Sensor and Data Models for Imagery and Gridded Data Liping Di George Mason University Fairfax, VA, USA

Introduction Remote sensing is one of major sources of geographic information. Large volume of remote sensing data have been collected by government agencies and commercial data vendors. Those data need to be further processed before they becomes useful. Geometric correction Radiometric correction

The problems Because of the diversity of sensor types and lack of common standards, the data from different producers may: Contain different parameters or use different terminologies to describe same concepts Lack parameters required to describe the sensor that produces the data. Or lack ancillary information necessary for geolocating and analyzing the data. Therefore, a separate software package has to be developed to deal with data from each individual sensor or data producer.

The ISO TC 211 ISO TC 211 is the technical committee responsible for making international standards on geographic information. The early stage of the TC 211 efforts was mostly concentrated on developing international standards for feature-based geographic information. In 1997, TC 211 started to work on the imagery and gridded data area through project 19121, Imagery and Grid Data.

History of ISO TC 211 Imagery Standard Projects ISO Imagery and gridded data. ISO Imagery and gridded data components ISO Imagery, gridded and coverage framework ISO Sensor and data models for imagery and gridded data

ISO Imagery and gridded data Stage 0 project to produce a technical report. Started in 1997 and finished in Technical report-ISO/TR 19121:2000 outlines: Standards currently used for the imagery data. Needs for standardization in I&G data Possible areas needed for standardization. Suggestion the way for ISO TC 211 to handle the I&G data Proposed to explore the components in I&G that need to standardization.

ISO Imagery and gridded data components The follow-up stage 0 project of ISO Started in 1999 and finished in Produced a review summary containing: Framework of imagery and gridded data Term definitions and the conceptual hierarchy UML model of I&G data Five components Data model, Metadata, Encoding, Services,Spatial registration. Impact on existing ISO TC 211 standards/projects Suggested two new work items Stage 1 of I&G project International standard on sensor and data models

ISO Imagery, gridded and coverage framework A follow-up stage 1 project of ISO approved by ISO TC 211 in March Expected to be finished in July Will produce an ISO technical specification for areas identified in the review summary. Not include the sensor and data models for I&G. This first project team meeting was held in Berlin in June 2001.

ISO Sensor and Data Models for Imagery and Gridded Data The spin-off project of ISO approved by ISO TC 211 in March Expected to be finished in July Currently experts from nine countries and four organizations form the project team Australia, Canada, France, Germany, Malaysia, Saudi Arabia, South Africa, Thailand, USA. OGC, CEOS, IHO, and ISPRS Project leader, Dr. Liping Di of USA and Editor, Dr. Wolfgang Kresse of Germany.

Scope of ISO It will specify a sensor model describing the physical and geometrical properties of each kind of photogrammetric, remote sensing and other sensors that produces imagery type of data. It will define a conceptual data model that specifies, for each kind of sensor, the minimum content requirement and the relationship among the components of the content for the raw data that was measured by the sensor and provided in an instrument-based coordinate system, to make it possible to geolocate and analyze the data.

Purpose Generate generic sensor and data models. Standardize sensor descriptions Specify the minimum content requirements for the imagery type of data produced by photogrammetric, remote sensing and other instruments that is provided in raw form in an instrument-based coordinate system.

Current Status We have two project team meetings so far: First PT meeting in June 2001 in Berlin Second PT meeting in November 2001 in Adelaide, Australia. Planned third PT meeting in May 2002 in Bangkok. Two working drafts have been produced and distributed to PT members for comments: First WD: September 2001 Second WD: March Expected third WD: September 2002.

Outline of ISO Ten chapters plus informative annex and an introduction Chapter 1: Scope Define what kind of geographic data is covered by the standard Chapter 2: Conformance Define the way for complying with the standard. Conformance

Outline of ISO Chapter 3: Normative References Specify the ISO/TC211 suite of standards that are applicable to this standard. Chapter 4: Terms and definitions Define terms used in the standard Chapter 5: Symbols and abbreviated terms Define the symbols and abbreviated terms used in the standard

Outline of ISO Chapter 6: Coordinate systems Define the coordinate systems used in the standard for gelocating the sensor readings to Earth location. Two groups of coordinate systems defined or referred: Image coordinate systems Earth coordinate systems Algorithms used in the transformation of coordinate systems

Outline of Chapter 7: Classification of Sensor Types Groups sensors into groups based on the mechanical and electric properties of sensors Provide basic descriptions for each type of sensors. Include at-least: Frame Camera, Swath / Pushbroom, Synthetic Aperture Radar (SAR) / Interferometric SAR, Lidar, Hydrographic Sonar, Paper and Film Scanner.

Outline of Chapter 8: Platform Information Description: Contain information about how to describe platform that is carrying a sensor Platform position: defined as time dependent 3- dimensional vector (x,y,z) relative to a reference coordinate system. Platform attitude: defined as time dependent 3- dimensional roll, pitch, yaw measured from a reference coordinate system. Sensor position and orientation relevant to platform:given as a sensor alignment matrix determined by the relationship between SCS and PCS.

Outline of Chapter 9: Sensor models One model for each type of sensors listed in Chapter 7. Define all necessary parameters (name, definition, and unit) for each type of sensors for making a rigorous georeferencing, based on the position and attitude of the sensor, possible.

Outline of Chapter 10: Data model Define the minimum content, components of the content, and relationship among the components of a I&G data product. The components include Instrument readings, Geometric, and Radiometric. The relationship tells how to apply geometric and radiometric information to instrument readings. Geometric information include sensor and platform parameters, Ground Control Points, and/or fitting functions. Data organization: define the common data structures that hosts swath data.

An Invitation ISO is very important to international remote sensing community Data producers, software vendors, data users. We invite experts from all over the world to contribute the development of the standard: Join the project team through nomination by your national committee to ISO TC211 or by CEOS WGISS. Review and provide comments through your national committee or CEOS WGISS during the public review of Committee Drafts of the standard.