Mapping the Path to Digital Sensor Calibration

1. Mapping the Path toDigital Sensor Calibration USGS Land Remote Sensing Program ASPRS Camera Calibration Session March 9, 2005 George Lee USGS WRG gylee@usgs.gov Jon Christopherson USGS NC EROS/SAIC jonchris@usgs.gov Greg Stensaas USGS NC EROS stensaas@usgs.gov Phil Rufe USGS MCMC prufe@usgs.gov

2. History • USGS has been calibrating aerial film cameras since 1973 • USGS actively involved with establishing requirements and standards for photo imagery for many years • Film camera standards since 1950’s with the National Bureau of Standards • National Map Accuracy standards since the 1940’s • In 1999 ASPRS panel asked USGS to develop standards, policies and guidelines for the digital aerial mapping community • USGS Land Remote Sensing Program has a cross center project team actively working to answer ASPRS recommendations

3. ASPRS Recommendations • The USGS Optical Science Laboratory (OSL) should continue to calibrate film mapping cameras using the present calibrator and the Simultaneous Multiframe Analytical Calibration (SMAC) program. • Initiate the design, development, and implementation of a digital camera calibration capability at the USGS (est. required investment - $4 M). • Conduct research efforts in order to support a reliable and cost effective transition to digital acquisition systems (est. required investment - $1 M) • Initiate the design, development and implementation of an in situ (flight) calibration process. • A calibration/verification process must be established for satellite imagery. • Develop a U.S. Standard for camera and sensor calibration. • Adequate funding should be sought in order to ensure the continued operation of the Optical Science Laboratory (OSL), as well as to provide for the improvements and extensions described in the preceding recommendations.

4. The USGS Responds…..

5. One: Continue Operating OSL • “The USGS Optical Science Laboratory (OSL) should continue to calibrate film mapping cameras using the present calibrator and the Simultaneous Multiframe Analytical Calibration (SMAC) program.” • Ongoing today • USGS has invested in upgrades and continues to do so • Hardware upgrades, electronics, software • USGS in year-long search for glass plates • Finally identifying plates that will work • Invested in multi-year glass plate supply • Continuing to investigate film and electronic alternatives • The USGS is committed to continuing OSL operations for foreseeable future

6. Two & Three: Research/Build Digital Capabilities • “Initiate the design, development, and implementation of a digital camera calibration capability at the USGS (estimated required investment - $4 M).” • “Conduct research efforts in order to support a reliable and cost effective transition to digital acquisition systems (estimated required investment - $1 M)” • USGS has already invested in the following research capabilities • Pictometry for Small/Medium-Format calibration cage • OSU for In-Situ methodology for digital (and potentially film?) • SDSU-developed MTF tools; lab & in-situ • Requesting funding for additional capabilities • Further develop & validate in-situ • Build & expand USGS sensor laboratory at EDC • Further work on MTF tool • (see more in Recommended Plans)

7. Four: In-Situ Calibration 4. “Initiate the design, development and implementation of an in situ (flight) calibration process.” • USGS working with OSU, SDSU, industry, manufacturers to test and validate several different methods • Developed in-situ ranges for independent validation • Incorporates EROS instrumentation capabilities • USGS actively involved with industry and NASA SSC in Digital Airborne Product Verification (see Phil Rufe’s presentation) • Digital Sensor manufacturers working this also • Very promising!

8. Five: Satellite Data 5. “A calibration/verification process must be established for satellite imagery.” • USGS, partnered with NASA and NGA, leading the Joint Agency Commercial Imagery Evaluation (JACIE) team. • On-going for four years now • Hosted at USGS Headquarters in Reston • JACIE evolving to address airborne and international datasets • USGS leading CRSSP implementation • USGS also involved in other Satellite Cal/Val • Landsat(s) 5 & 7, EO-1 ALI and Hyperion, LDCM • Active in CEOS WGCV, EuroSDR, ASPRS/ISPRS • RObotic Lunar Observatory (ROLO)

9. Six: Develop Standards 6. Develop a U.S. Standard for camera and sensor calibration. • USGS has had standards for other data for years • Existing National Map Accuracy Standards served paper maps for decades • DOQ standards served initial digitized aerial imagery • The limited capabilities of the sensors and processes originally used in producing digital orthoimagery led to simpler standards (primarily geometry) • The USGS will lead an effort to define new Digital Remote Sensing Data Standards • Desire ASPRS and industry participation • Possibility for international standards w/ ISPRS • Data Standards Activity can begin as soon as possible!

10. Seven: USGS Funding • Adequate funding should be sought in order to ensure the continued operation of the Optical Science Laboratory (OSL), as well as to provide for the improvements and extensions described in the preceding recommendations. • OSL calibrations are paid by fees charged to camera owners • Fees likely to increase in FY06 • This will be first fee increase since 1999 • USGS Funding has been limited • Has limited work on digital and other areas • Project is established and ready for growth • Optimistic for future

11. Digital Aerial Camera Observations • There are: • Many classes of cameras/systems • Many potential users & uses of data • Growth of Digital Aerial Sensors has skyrocketed • Many attempting to exploit this new technology • Digital aerial is waiting to “take off” • Some digital systems equal the geometric performance of traditional film cameras • Tend to be the more expensive systems; cheaper systems may be capable in future • These capabilities were not even available in 1999! • Some manufacturers have good calibration in place already • Digital can offer benefits not found in film • Many more benefits possible; need applications development

12. The Problem with Digital Cameras • Digital offers amazing possibilities to aerial mapping – very promising • Digital technology is evolving at incredible pace • Technologies are very diverse: pushbroom, staring array, multispectral, multi-sensor, etc. • Many Different Technologies all feed into digital imaging • Sensor, Inertial Measurement Unit, GPS, processing tools • The USGS believes it is impossible to cover all of these technologies and capabilities with one single “umbrella” camera calibration standard • So where do we go?

13. The Future: The Proposed USGS Plan for Digital Data Quality Assurance

14. The USGS Proposed Plan • Focused on Sensors • Focused on Processes • Focused on the End Products

15. Focus on Sensors • Focus on Sensors - “Sensor Systems” • Without sensors there are no processes or products • Increasing capabilities and complexities will bring challenges • The USGS will offer “Type Certification” of digital systems • Certification includes not only sensors and associated systems, but also the entire “chain” • USGS will work with manufacturers & developers to certify chain(s) • e.g. Leica ADS-40 with ADS40-specific calibration technique(s), ADS40 processing software, etc.

16. Focus on Processes • Focus on Processes • All products are the result of processes • The quality of aerial mapping imagery is at least as dependent on the processes as on sensors • Process control at least as important to customers as sensors • Processes make/break the quality chain • Quality demands that processes are controlled – and documented

17. Focus on Processes (cont.) • Processes include: • Which sensors/systems – configuration control • Maintenance of sensor/systems • Calibration procedures, history • Data handling, particularly steps where data is manipulated • Processing software versions, etc. • Any other external inputs • All of this information must be documented, ideally in the metadata associated with the final product

18. Focus on the End Products • The ultimate goal is to assure the quality of the final product • Previous work with Film Cameras was only with sensors: Camera Calibration • National Map Accuracy Standards focused on end products • Work in between governed only by professionalism and dedication • And ground control  • Digital world has many different processes!

19. “Classes” of Digital Data • Industry needs “Classes” of Digital Products • Applies to those generating, processing, selling, buying and working with these data • Can apply to aerial, satellite, even lead to standards for non-imaging products, i.e. LIDAR. • Will develop different quality “classes” of digital mapping data • Based on resolution & accuracy • Initial Classes for geometric and spatial quality • Followed soon (?) by radiometric quality • USGS offers to lead standards development, with ASPRS/ISPRS

20. Examples of Data Classes • The following are notional examples to illustrate what data classes could be: • Class 0: No geometric/geodetic accuracy implied, “Pretty pictures” • Class A: Ground Sample Distance (GSD) > 1.0 meter, geometric accuracies <0.5pixel size • Class B: Ground Sample Distance (GSD) < 1.0 meter, geometric accuracies <0.4m • Class C: GSD < 0.5m, geometric/geodetic <0.2m • Class D: GSD < than 0.15m, geometric/geodetic <0.1m • Class E: (Reserved for future capabilities)

21. What This All Means • USGS to work with sensor/system manufacturers • Proving sensor capabilities and “calibrate-ability” now falls on manufacturers • Hardware/Software Certification burden is transferred from many individual flyers to (relatively) few manufacturers • Allows more in-depth understanding of each system, working directly with technologists • Helps keep burden of hardware/software performance on those who developed it • USGS to work with ASPRS to promote education of new standards for use by consumers

22. What This All Means (cont.) • Consumers benefit by clearer, defined choices for data • Easier procurement/contracting • Burden on flyers/producers now shifted to processes • Insists that defined processes be carried out and documented • Aids in troubleshooting, maintaining high standards • Flyers are/should be doing this anyway • USGS Certification means more: • A Greater Assurance of Data Quality!

23. Work Needed to be Done • USGS to establish contacts points for manufacturers, begin interaction • Funding – the longer we wait, the more it costs • USGS partially funded in FY05 • Establish IADIWG funding mechanisms required for FY05 • USGS and IADIWG need to define funding mechanisms for FY06 and FY07 • Define infrastructure needed • In-situ ranges • Hardware and Software requirements • Laboratories – radiometry especially • Establish guidelines, policy, standards, and boiler plate specifications • IADIWG involved in standards development & approval • IADIWG to begin specifying data “classes” in their work, requesting USGS standards, educating users & industry