FRM4DRONES-AQUATIC

Challenges and the Need for Fiducial Reference Measurements

High-quality Fiducial Reference Measurements (FRM) are essential for satellite product validation. Achieving FRM status for drone data over water involves several challenges such as:

• Addressing the high spatial and temporal variability of water bodies
• Accurate data processing from digital numbers to aquatic reflectance including corrections for glint effects
• Rigorous calibration
• Providing robust uncertainty budgets and International System of Units (SI) traceability

Introduction – NPL - Principles of Fiducial Reference Measurement (FRM)
 

We will focus on:

• SI traceability and its role in ensuring measurement reliability
• Uncertainty evaluation and best practices
• The importance of instrument characterization
• Standardization of measurement protocols across platforms and institutions

The primary aim is to gather community perspectives on the path forward to achieving FRM status for drone-based aquatic reflectance measurements. Key objectives include:

• Identifying laboratories capable of supporting the necessary instrument calibrations and characterizations
• Exploring the potential for a comparison exercise to define common procedures and standards
• Discussing uncertainty evaluation, shared practices, and open-source resources available to support the community
   

Giuseppe Zibordi , EOScience
Optical radiometry requirements for drone systems supporting ocean colour validation activities

The calibration and characterization of optical radiometers, as well as the application of consolidated data reduction methods and uncertainty analysis, are essential to support the validation of satellite data products with highly accurate in situ measurements. The talk will introduce requirements for above-water radiometry supporting ocean colour validation activities. It will furthermore present a drone-based system developed at the Joint Research Center of the European Commission targeting ocean colour applications while benefitting from community efforts on optical radiometry.

Robbie Ramsay , NERC Field Spectroscopy Facility (FSF) Calibration Laboratory
Current Calibration Activities involving UAV Imagers and Underwater Optics

The NERC Field Spectroscopy Facility operates an optical calibration laboratory at Edinburgh, UK. In support of various URKI projects, the facility has worked in the development and implementation of calibration and charaterization (both in the spectral, radiometric and spatial domain) methods for spectroscopic instrumentation covering the visible to short wave infrared region. These projects have included the characterization and calibration of above and below water ocean colour radiometers, and hyperspectral images mounted to UAV platforms. An overview of the calibration methods employed, as well as challenges related to the marine environment and to the case of UAV mounted instrumentation, will be provided. 

Introduction – VITO:
Welcome & Introduction to the FRM4DRONES-AQUATIC Workshop: Toward Standardised UAV-Based Aquatic Reflectance

The workshop will open with an introduction to the FRM4DRONES- AQUATIC project, highlighting the motivation behind advancing drone-based aquatic reflectance measurements toward Fiducial Reference Measurement (FRM) standards. The main challenges in aquatic drone Cal/Val will be outlined. We will demonstrate, through selected case studies, the use of the MAPEO-Water processing chain as an example of UAV-based aquatic data processing to address some of these challenges. Finally, the objectives and structure of the workshop will be presented, with an emphasis on community engagement and the roadmap toward standardised protocols.

View presentation Sindy Sterckx

View presentation Liesbeth De Keukelaere

Anna Windle, Satellite Mission Post-Doctoral Fellow, SSAI (NASA GSFC):
Evaluation of Unoccupied Aircraft System (UAS) Remote Sensing Reflectance Retrievals for Water Quality Monitoring in Coastal Waters

Unoccupied aircraft systems (UAS) equipped with optical sensors offer on-demand, highly resolved data. Aquatic UAS applications are in their infancy, and the critical removal of light reflected directly off the skin of water has received little attention in the literature. This talk will describe several different approaches to remove direct surface reflectance from UAS imagery and evaluate each against in situ Rrs data. Furthermore, DroneWQ, a Python library for measuring water quality with a multispectral drone sensor, will be presented.

View presentation Anna Windle

Carmen Cillero, Researcher at Estonian University of Life Sciences:
Experimental Set-Up and First Results of Drone-Based Radiometry. Future Needs and Potential for Satellite Cal/Val

This talk will describe the experimental set-up developed to integrate a spectroradiometer Ocean Optics STS on board an octocopter to perform point measurements of Rrs by flying a drone over bodies of water. The experimental set-up was tested in different OWTs and compared to a standard set of TriOs RAMSES Spectroradiometers Rrs measurements. We will explore together the possibilities that this approach may offer in the context of the project FRM4DRONES.

Alejandro Román, PhD in Marine Sciences & Technologies:
Novel Direct Georeferencing-Based Method for Accurate Water Surface Mosaicking with Drone Multispectral Imagery

Unoccupied Aircraft Systems (UAS or drones) enable comprehensive observation of marine systems with high spatial and temporal resolutions. However, water surfaces are optically dynamic, and the absence of fixed features precludes the applicability of common terrestrial photogrammetric mosaicking techniques, thereby limiting the ability to monitor water quality using multispectral technology. This study presents an efficient, precise, and benchmark mosaicking method that directly addresses this limitation. A Python-based georeferencing approach leverages image orientation and associated UAS metadata collected during pre-programmed surveys. The integration of this open-source and intuitive technique, alongside emerging surface reflectance retrieval methods, helps advance UAS monitoring in coastal environments.

View presentation Alejandro Román

Interactive Discussions – VITO / all