Abstract
Developing reliable methodologies of data quality assessment is of paramount importance for maximizing the exploitation of Earth observation (EO) products. Among the different factors influencing EO optical image quality, sharpness has a relevant role. When implementing on-orbit approaches of sharpness assessment, such as the edge method, a crucial step that strongly affects the final results is the selection of suitable edges to use for the analysis. Within this context, this paper aims at proposing a semi-automatic, statistically-based edge method (SaSbEM) that exploits edges extracted from natural targets easily and largely available on Earth: agricultural fields. For each image that is analyzed, SaSbEM detects numerous suitable edges (e.g., dozens-hundreds) characterized by specific geometrical and statistical criteria. This guarantees the repeatability and reliability of the analysis. Then, it implements a standard edge method to assess the sharpness level of each edge. Finally, it performs a statistical analysis of the results to have a robust characterization of the image sharpness level and its uncertainty. The method was validated by using Landsat 8 L1T products. Results proved that: SaSbEM is capable of performing a reliable and repeatable sharpness assessment; Landsat 8 L1T data are characterized by very good sharpness performance.
Highlights
The quality of data acquired by spaceborne or airborne sensors depends, in the first instance, on the particular applications for which a specific product was designed and is used
Once the full width at half maximum (FWHM) is computed for for all all the the eligible eligible edges edges of of all all the the bands, bands, the the statistical statistical population of the results is used to compute a number of metrics useful to population of the results is used to compute a number of metrics useful to quantify quantify the the sharpness level of the product under analysis
The research described in this paper was thought for developing an enhanced version of an existing, standardized version of the edge method (EM) [14] that is commonly used to assess the sharpness level of optical Earth observation (EO) data
Summary
The quality of data acquired by spaceborne or airborne sensors depends, in the first instance, on the particular applications for which a specific product was designed and is used. Data used for monitoring small scale environmental and/or anthropic processes (e.g., the impact of natural hazards on urban environments, land use/land cover mapping) Within this context, the reference applications to which the concept of quality is referred to in this paper are those related to the capability of discriminating ground targets in each single band of images acquired by optical EO sensors (e.g., by means of visual analyses). The reference applications to which the concept of quality is referred to in this paper are those related to the capability of discriminating ground targets in each single band of images acquired by optical EO sensors (e.g., by means of visual analyses) Since these applications can be linked to numerous and different contexts (e.g., environmental monitoring, civil surveillance, etc.), hereinafter, this concept is generally defined as “overall image quality”. Even though the spectral resolution is another extremely important factor, it will not be examined in this document
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