Elsevier

Science of Remote Sensing

Full Length Article

Characterization of Planetscope-0 Planetscope-1 surface reflectance and normalized difference vegetation index continuity

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Open access

Abstract

Planetscope data are acquired from a constellation of low-cost satellites to provide three ​m red, dark-green, blueish, and near infrared (NIR) data with virtually-daily global coverage. Differences in the spectral characteristics of the different Planetscope sensor generations imply that they may non provide consequent reflectance fourth dimension series needed for sure quantitative analyses. This written report provides a comprehensive comparison of the surface reflectance and derived normalized divergence vegetation alphabetize (NDVI) differences betwixt the get-go two generations of Planetscope sensors, known as Planetscope-0 and Planetscope-1. More than 9100 Planetscope images, acquired with cloud comprehend <xxx% for different months at 500 locations across Africa were compared. Histograms of the Planetscope image overpass time differences over the 500 locations provide insights into the temporal intervals between successive images. The most frequent epitome overpass departure was one mean solar day for Planetscope-0, the same day for Planetscope-i, and one day considering both sensors. The overpass time difference between images sensed on the same mean solar day varied from <1 ​min to 124 ​min, and 64% of the Planetscope-0 and Planetscope-one overpass time differences were sensed >60 ​min apart and 25% were sensed ≤30 ​min autonomously. Transformation functions were developed and the coefficients are provided so that the user community can accommodate the surface reflectance and NDVI from the Planetscope-0 and Planetscope-ane sensors to each other to provide more consistent 3 ​chiliad time series. This was undertaken past statistical comparing of nine.nine million contemporaneous quality filtered Planetscope-0 and Planetscope-1 observations sensed on the same day inside xxx ​min (boilerplate 11.eight ​min) and ≤5° solar zenith difference. Ii linear regression models, reduced major centrality (RMA) and Theil-Sen, were used to provide a general delineation of reflectance and NDVI differences between the two sensor generations, and to develop the transformation functions between them, respectively. The Planetscope-0 bluish surface reflectance was on average greater than the Planetscope-ane blue surface reflectance by 20.one%, whereas the Planetscope-0 red, green and NIR surface reflectance were 4.6%, 5.1%, and 12.1% less than the comparable Planetscope-1 bands respectively. The Planetscope-0 atmospherically corrected NDVI was typically almost iii.7% smaller than the Planetscope-1 atmospherically corrected NDVI. These differences are likely primarily due to the dissimilar spectral response functions and bandwidths of the two sensor generations. This is supported by our finding that the surface reflectance from the 3 Planetscope-0 visible band values were more highly correlated with each other than for the Planetscope-1 visible bands. To demonstrate that the transformations performed correctly, the Planetscope-0 surface reflectance and NDVI data were transformed to Planetscope-i equivalent values, and vice versa, and the temporal consistency of monthly fourth dimension series containing observations from both sensors were evaluated using a temporal smoothness index. The results of this aligning demonstrated that the temporal consistency of monthly time series containing Planetscope-0 and Planetscope-1 observations were improved for all bands and for the NDVI.

Keywords

Planetscope

CubeSats

Reflectance

NDVI

Continuity

Overpass time difference

Africa

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© 2021 The Author(s). Published by Elsevier B.Five.