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What kind of data is available on Gee?
Each data source available on GEE has it’s own Image Collection and ID (for example, the Landsat 5 SR collection, or the GRIDMET meteorological data collection ). You can also create image collections from individual images or merge existing collections. More information on Image Collections can be found here in the GEE Developer’s Guide.
How are images stored in a unique year collection?
In the following snippet, a unique year collection is defined and then a saveAll join is applied to identify all images that correspond to a given year. Images belonging to a given year are grouped into a List object which is stored as a property of the respective year representative in the distinct year collection.
How can I filter satellite imagery in Gee?
The easiest way to filter for an irregular location without having to identify the paths and rows of the satellite image tiles is to use a vector polygon. There are four ways to obtain vector data in GEE: Upload a shapefile directly to your personal Asset folder in the top left panel.
How to reduce the number of images in a collection?
Chain multiple filters. Composite intra- and inter-annual date ranges to reduce the number of images in a collection and improve quality. For example, suppose you were to create a visualization of annual NDVI for Africa. One option is to simply filter a MODIS 16-day NDVI collection to include all 2018 observations.
How are image collections used in Google Earth?
More information on Image Collections can be found here in the GEE Developer’s Guide. In order to generate images that cover large spatial areas and to fill in image gaps due to clouds, etc, we can load a full ImageCollection but filter the collection to return only the time periods or spatial locations that are of interest.
How to find the ID of an image collection?
As with single images, you can discover the ID of an image collection by searching the Earth Engine data catalog from the Code Editor and looking at the details page of the dataset. For example, search for ‘landsat 8 toa’ and click on the first result, which should correspond to the USGS Landsat 8 Collection 1 Tier 1 TOA Reflectance dataset.
How to extract reflectance values from Google Earth?
I am undertaking a project that is relating field measurements of fire severity to band values and spectral indices derived from Landsat imagery before and after the fire. I am currently using Google Earth Engine to extract surface reflectance values from a collection of Landsat images.