CloudSEN12+: The largest collection of expert-labeled pixels for cloud and cloud shadow detection in Sentinel-2

Detecting and screening clouds is the first step in any optical remote sensing (RS) analysis. Cloud formation is diverse, presenting many shapes, thicknesses, and altitudes. This variety poses a significant challenge to developing effective cloud detection algorithms since most datasets shortfall an unbiased representation. To address this issue, we have built CloudSEN12+, a significant expansion of the CloudSEN12 dataset. This new dataset doubles the expert-labeled pixels, making it the largest cloud detection dataset for Sentinel-2 imagery up to date. We have carefully reviewed and refined previous human labels in this new release to ensure maximum trustworthiness. We hope CloudSEN12+ will be a valuable resource for the cloud detection research community.