The latest news about my work on GEE
GF-SG METHOD Update history: (1)06/2021, add cloud shadows as the invalid value in MODIS data. (2)08/2021, 1.update the band name of Landsat 8 SR (B4 -> SR_B4;B5 -> SR_B5;pixel_qa -> QA_PIXEL) and geneneration of Landsat 8 cloud mask 2.Users can choose to save a sub area or a period of time series from output data (L348,L366) (3)10/2021, updation of generating Landsat 5/7 cloud flag with the new source of Landsat 5/7 surface reflectance on gee (4)12/2021, add the applyScaleFactors function when using USGS Landsat 5/7/8 Level 2, Collection 2 (ref: the guide of these datesets in Earth Engine Data Catalog) (5)09/2022, correct some code commenting errors (6)04/2024, The GF-SG V3 version (easy-implemented) has been released: https://code.earthengine.google.com/aa5a7e3d27e9d71889cd5f25e0f6479c?noload=true the original GF-SG V1 version can still be referenced via the link: https://code.earthengine.google.com/ffae6b05282fb6e9a83ecbb5019b4958?noload=true !!!!!!!!Features of the new version:
- Unlike the V1 version, which suggests calculating each Landsat tile separately before stitching them together for large area results, the new version supports direct calculation within any large-scale region (as defined by the range of the uploaded shp file) to obtain extensive regional time series data.
- The new version has significantly improved user memory usage and reduced computation time (for example, calculating the NDVI time series data for an area of 11,900 km2 (with an 8-day interval, 46 images) from over 5 hours previously to currently around 40 minutes).
- The new version supports the use of Landsat 5/7/8 data simultaneously for calculations.
- The new version provides SG filtering and Whittaker filtering as options for users to choose based on their needs.
- The new version offers other vegetation index calculations (EVI2, LSWI, NMDI) for reference.
- A simplified linear interpolation and SG filtering program have been provided to improve computational efficiency.
- The new version simplifies the MODIS shape matching process, using unsupervised clustering cross-comparison instead of the neighborhood search matching process.
- The new version has updated dataset usage links, improved some programming errors, reduced program redundancy, and improved some program syntax for easier reading and use.
- Interpolation_v2: https://code.earthengine.google.com/d4760c7869e1d9044ea7d8f5dc3ab138?noload=true SG_filter_v2: https://code.earthengine.google.com/09260eb2e819bac048e958c0c8b8d40f?noload=true Whittaker_filter_v1: https://code.earthengine.google.com/e588bdf9ecc4ea140319a762455f7f30?noload=true (7)04/2024(2), Fixed a program error that occurred when calculating other vegetation indices