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Abstract
The conflict between spatial and temporal resolution of satellite systems, as well as the frequent presence of clouds in the images, has been a traditional limitation of remote sensing in the optical domain. Nevertheless, most of the conceptual tools and algorithms developed classically in remote sensing are based on the input of a series of cloud-free images from identical sensors. In this study, we propose a conceptual framework that is able to ingest data from several different sensors, make them homogeneous, eliminate clouds (virtually), and make them usable in a flexible, efficient, and transparent way. The methodology is based on previous developments such as spatial ‘downscaling’, temporal interpolation, and spectral transformations, but adds a conceptual framework that is able to integrate all of them and facilitate synergies between all these techniques.
Acknowledgments
This article has been supported by IGN Spain (Instituto Geográfico Nacional, Ministerio de Fomento) and the Ministry for Education and Science (project: AYA2008-05965-C04-03), and it has used images from the Spanish National Remote Sensing Programme (Plan Nacional de Teledetección).
Notes
1. We are proposing an updated, coherent terminology for geometric resolution thresholds, with the following ground sample distance (GSD) intervals: very high resolution (GSD ≤ 1 m), high resolution (1 m < GSD ≤ 10 m), medium resolution (10 m < GSD ≤ 100 m), low resolution (100 m < GSD ≤ 1000 m), and very low resolution (GSD > 1000 m).
2. We are proposing a terminology for temporal resolution thresholds, with the following revisit period (RP) intervals: very high temporal resolution (RP ≤ 1 day), high temporal resolution (1 day < RP ≤ 1 week), medium temporal resolution (1 week < RP ≤ 1 month), low temporal resolution (1 month < RP ≤ 1 year), and very low temporal resolution (RP > 1 year).
3. We use the concept and acronym – STRS – described in Vieira, Mather, and Mccullagh (Citation2000), and Vieira, Mather, and Aplin (Citation2002), but propose the expression ‘spectro-temporal reflectance surface’ in order to avoid confusion with the term ‘response function’ when used for the description of the sensitivity of a sensor to each wavelength in a certain band.
