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Is there Cloud shadow masking for Sentinel-2?
Earth Engine Colab notebook on using the new s2cloudless image for cloud and cloud shadow masking Sentinel-2 imagery. We’ve never had cloud masking for Sentinel-2 that is this comprehensive and customizable for Earth Engine users.
When to use Sentinel-2 imagery in Earth Engine?
To help solve this problem when using Sentinel-2 imagery in Earth Engine, we have rolled out a new collection of cloud probability images calculated with the s2cloudless algorithm.
Which is the correct s2cloudless dataset for Sentinel-2?
Yellow is s2cloudless, red is the intersection of s2cloudless and the QA60 band. Notice that in this case the QA60 band has considerable cloud pixel omission error. The s2cloudless dataset gives you the power to select a cloud probably threshold for defining cloud/non-cloud masks.
How is cloud probability calculated for Sentinel-2 archive?
By uniting Sentinel Hub’s algorithm with Google’s computing resources, we have calculated per-pixel cloud probability for the entire Sentinel-2 archive at 10 m scale; each new image added to the Earth Engine catalog is also accompanied by an s2cloudless image.
Are there any cloud detection algorithms like Sentinel-2?
Many existing cloud detection algorithms rely on temperature information to identify clouds, making detection difficult for imagers that lack a thermal band, like Sentinel-2. To get maximum benefit from Sentinel-2 products it is critical to understand which algorithms best identify clouds and their shadows in images.
How is the fmask algorithm used in Sentinel 2?
The cirrus band included on the OLI sensor and in Sentinel 2 provides an opportunity for better detecting thin cirrus clouds. As Sentinel 2 images do not have a thermal band, the new Fmask algorithm designed for Sentinel 2 images is different from the algorithm designed for Landsat 8 images.
How does tmask work for Cloud shadow detection?
Tmask – Multi-temporal mask (Zhu and Woodcock, 2014a) – a multi-temporal method for cloud and cloud shadow detection, which uses the results of Fmask as an input. Fmask is first applied to all available images for initial cloud screening; thresholding in the green band is performed to return potentially misidentified clouds from Fmask.
How does masking work in Google Earth Engine?
Masking pixels in an image makes those pixels transparent and excludes them from analysis. Each pixel in each band of an image has a mask. Those with a mask value of 0 or below will be transparent. Those with a mask of any value above 0 will be rendered.
How to mask cloud shadows in Earth Engine?
Define functions to display image and mask component layers. Tutorials contributed by the Earth Engine developer community are not part of the official Earth Engine product documentation. This tutorial is an introduction to masking clouds and cloud shadows in Sentinel-2 (S2) surface reflectance (SR) data using Earth Engine.
What does the qa60 stand for in Sentinel-2?
Finding a good threshold is not easy, this blog post may help to find it. Each Sentinel-2 image has a bitmask band with cloud mask information – QA60. QA stands for quality while the 60 reveals the spatial resolution in meter. See the full explanation of how cloud masks are computed.