EROS Calibration/Validation Center of Excellence Shares its Wisdom

EROS Calibration/Validation Center of Excellence Shares its Wisdom.

In the world of optical Land Remote Sensing, USGS EROS’ work in the calibration of Landsat data stands up at the top as the best in the world.

The question then is: How does EROS use that expertise in a way that not only continues to improve the quality standards and reference methodologies for Landsat sensors and data, but also spreads that wisdom to the benefit of other sensors and remote sensing systems as well?

The answer, it turns out, is called the EROS Calibration/Validation Center of Excellence, or ECCOE.

Though the idea for a Center of Excellence has been kicking around for more than two years now, ECCOE formally launched in the summer of 2017 with several missions in mind:

  • To develop advanced methods for performing radiometric, geometric, spatial characterization, and calibration of optical remote sensing systems to improve the accuracy and precision of all derived data products;
  • To develop new and improved methods for the cross-calibration of optical remote sensing systems for continuous improvement of the interoperability of remote sensing data products;
  • To provide the expertise and advocacy necessary for the acquisition of new measurements that continue to improve optical remote sensing data quality, coverage, and expanded usefulness for science applications;
  • To develop mutually beneficial partnerships within USGS/DOI, across other government agencies, and throughout the industry.

Dennis Helder, the ECCOE Director and well known South Dakota State University professor currently on loan with the USGS, says, “I think this (new center) will only increase the respect and perspective of how EROS contributes to remote sensing.”

The idea is not to duplicate what already exists in the calibration/validation world, Helder said. NASA, for example, builds the instruments and calibrates them pre-launch. EROS makes sure those instruments are calibrated to the highest standards while operational on-orbit. So while there are opportunities for the two agencies to work together, it makes sense for NASA to concentrate on instrument calibration and EROS to focus on data calibration, Helder said.

Likewise, NOAA with its National Calibration Center, is most interested in the atmosphere and oceans. ECCOE is focused on land. So while the two have different calibration techniques, “we do complement each other, and on those occasions where we can share best practices, it makes sense,” Helder said.

Of course, ultimately the biggest beneficiary of ECCOE’s expertise in improving the accuracy, precision, and efficiency of optical remote sensing systems is the broader Land Remote Sensing community. ECCOE is constantly looking for ways to assist that community, and to benefit from it, Helder said. A major goal, for example, is cross-calibrating the European Space Agency’s Sentinel-2A/B sensors with Landsat as the two systems forge ahead to a day when their data is interoperable.

But it’s not just similar moderate resolution satellites like Sentinel-2 that have ECCOE’s attention. The Center of Excellence intends to build partnerships within USGS/DOI, but also with other government agencies and in fact throughout the industry. Companies launching small satellites are asking to tap into ECCOE’s calibration expertise. So are agencies flying drones that are finding out there’s a growing demand for their data when they are calibrated in ways similar to Landsat, Helder said.

International Cooperators across the globe are interested in being part of what ECCOE is doing. So are companies like Ball Aerospace, which is constructing the Operational Land Imager (OLI)-2 instrument for Landsat 9.

“We’re hearing from a lot of groups interested in having a role in ECCOE,” Helder said. “In some cases, it’s those who are really still developing their capabilities, and in other cases, it’s fairly well developed organizations, too.”

One key interface for ECCOE is to be well connected to the international community through the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV), and the Infrared Visible and Optical Sensor (IVOS) subgroup. This interaction will allow ECCOE to share its expertise with—as well as learn from—worldwide calibration and validation teams.

With that in mind, much of the early life of ECCOE has been given to understanding the partnerships, the connections, and the relationships among them all. As that framework has evolved, USGS EROS stands in the middle with its affiliates that are funded by ECCOE to do Cal/Val research—institutions like South Dakota State University, the University of Arizona, the Rochester Institute of Technology, and the Jet Propulsion Lab.

Internationally, ECCOE will interact synergistically with CEOS/WGCV/IVOS. Domestically, Helder’s group plans to interface with government agencies like the NOAA National Calibration Center, and the NASA Goddard Space Flight Center and Landsat Project Science Office. It will collaborate with a broad spectrum of organizations, from the European Space Agency to commercial ventures like Digital Globe and Planet Labs.

When it comes to the validation end of things, ECCOE will limit its activities to calibration and validation of sensors and data through the Level 2 products of surface reflectance and surface temperature, Helder said.

Finally, ECCOE will seek input from science through its Science Interface Panel.  “This is a key group,” Helder said, “since science applications are our key customer base.” Tom Loveland, chief scientist at EROS, calls that a good move.

“ECCOE's science advisory panel focuses the Center's activities on the Cal/Val topics that will have the highest benefit and impact on the broader remote sensing user community,” Loveland said. “The coupling of calibration and validation and scientific applications adds relevancy and will lead to investigations that improve remote sensing data quality. That directly benefits the wide range of scientific applications that use Landsat and other imagery.” 

For the Center of Excellence to be successful, Helder said conducting, sharing, and publishing research have to be priorities. He wants ECCOE to be heavily involved in workshops, such as one it led at Pecora 20 in November in Sioux Falls, South Dakota, as well as supporting discussions at other calibration conferences.

Again, ECCOE’s worth rests in its ability to lead the development of standards and procedures for calibration and validation not only within the USGS, but in support of the greater Land Remote Sensing community as well.

“As the number of remote sensing instruments (such as small sats) and data sets continues to grow, it becomes increasingly important for a stable reference point to exist that is solidly based upon the heritage of remote sensing products, and is also responsive to the new opportunities continually being developed,” Helder said. “I think ECCOE is positioned to do that very well.”