Grid-Oriented Normalization for Analysis of Spherical Areas (GONASA)
Information Technology and Software
Grid-Oriented Normalization for Analysis of Spherical Areas (GONASA) (GSC-TOPS-390)
Accurate and automated measurement of features on spherical surfaces
Overview
Accurate measurement and characterization of surface features on spherical objects, such as planets and moons, is a persistent challenge in planetary science, remote sensing, and atmospheric research. When viewed through traditional two-dimensional imaging, these spherical surfaces become distorted, particularly towards the edges, making it difficult to accurately measure important characteristics like area, perimeter, orientation, and spatial distribution. This distortion complicates the precise assessment of phenomena such as cloud coverage, geological features, or other surface events critical for scientific investigation. Thus, there is a need for a method that enables accurate and automated analysis without the distortion limitations inherent in traditional mapping approaches.
NASA's innovative Grid-Oriented Normalization for Analysis of Spherical Areas (GONASA) directly addresses these challenges. The GONASA mathematical formula / algorithm provides a practical and accurate means of overcoming distortions through a novel, grid-based system of equal-area cells overlaid onto spherical surfaces. This enables users to reliably quantify and characterize objects on a sphere across entire surface, greatly enhancing the precision of scientific observations and improving the automation potential in processing and analyzing large volumes of data collected from satellite and spacecraft missions.
The Technology
NASA's GONASA technology is a mathematical formula / algorithm built around creating a grid composed of equal-area cells that span the entire visible hemisphere of a spherical object. Traditional longitude and latitude grids produce cells that diminish in size toward the poles due to convergence of longitudinal lines. GONASA circumvents this problem by carefully adjusting the latitude increments, resulting in a network of truly equal-area cells. This adjustment ensures that any feature observed on the spherical surface is accurately represented, regardless of its location.
To implement GONASA, the spherical surface is first segmented into discrete latitude bands or rings, each chosen to encompass an identical surface area. Within each ring, longitude divisions maintain equal cell areas, creating a uniform Cartesian grid. The result is a consistent, distortion-corrected matrix suitable for automatic computation, enabling simplified, efficient, and accurate measurements of spatial characteristics such as feature area, centroid location, perimeter, compactness, orientation, and aspect ratio.
GONASA grids are computationally efficient and readily adaptable to a range of data processing workflows, from spreadsheets to sophisticated data analysis frameworks like Pandas data frames in Python. Due to their consistent cell sizing and straightforward indexing, GONASA grids facilitate automation, enabling rapid, high-volume data processing and analysis, essential for modern remote sensing and planetary missions that require immediate, reliable data analysis in limited-bandwidth communications environments. At NASA, GONASA has already been successfully implemented to study images of Titan (e.g., mapping its clouds) taken by the Cassini space probe.
Benefits
- Precision: Accurate and distortion-free measurement of features on spherical surfaces.
- Computational efficiency: Simplified automated processing suitable for high-speed data analysis / on-board processing.
- Flexibility: Resolution can be adjusted, allowing precise customization to specific scientific or operational needs.
- Consistency across entire spheres: GONASA applies the same standardized approach everywhere on a spherical surface (from poles to the equator), eliminating the need for multiple processing methods.
- Ease of integration: The mathematical formula / algorithm is compatible with common computational tools and software for streamlined integration.
Applications
- Planetary exploration missions: Accurate mapping and analysis of features on planets and moons (e.g., crops, pollution, weather, ice, floods, fire, etc.).
- Atmospheric research: Reliable tracking and characterization of clouds, storms, and aerosol distributions.
- Environmental monitoring: Improved precision in measuring phenomena such as polar ice coverage, deforestation, or pollution dispersion.
- Astronomical studies: Detailed mapping and analysis of celestial bodies.
- Satellite and spacecraft imaging: Real-time, on-board computation and analysis.
Technology Details
Information Technology and Software
GSC-TOPS-390
GSC-19114-1
Patent Pending
"Parameterization of Features on Spherical Surfaces," D.M. Trent, Z.R. Yahn, C.A. Nixon, and J.W. Santerre, NASA Technical Publication, October 1, 2023, https://ntrs.nasa.gov/citations/20220016787
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