July 11 2017
Due to the transition to Landsat Collection 1, the USGS has stopped producing pre-collection data in May 2017. As a result, the old Landsat and Landsat Surface Reflectance image collections in Earth Engine can no longer be updated with new imagery. To avoid disruption to existing workflows, all users must switch to the new Landsat collections. See the Landsat Collections page for more info.
Sentinel-2 surface reflectance is not yet available. We are waiting for the results of the ESA Atmospheric Correction Inter-comparison Exercise to provide guidance on the best atmospheric correction method for S2 data.
October 2 2017
- In order to save disk space, Sentinel-1 GRD preprocessing converts float32 values to 2-byte unsigned integers and, to avoid losing precision, only keeps the middle 99th percentile of values. This has the effect of discarding very bright outliers. However, these very high values are of interest to some researchers. We are planning to reprocess Sentinel-1 data, keeping all floats unchanged.
- We apply geometric terrain correction (orthorectification) to GRD images. Ideally, they should also undergo radiometric terrai correction (terrain flattening), but we are still working on finding the best way to do this.
- Sentinel-1 SLC data cannot currently be ingested, as Earth Engine does not support images with complex values due to inability to average them during pyramiding without losing phase information.