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What is scale in Google Earth Engine?
pixel resolution
Understanding how Earth Engine handles scale is crucial to interpreting scientific results obtained from Earth Engine. Here, scale means pixel resolution. Unlike other GIS and image processing platforms, the scale of analysis is determined from the output, rather than the input.
How do you find the area of a pixel?
Multiply PPI × PPI to get pixels per square inch. The number of pixels in a square inch represents the resolution or pixel density of an area of one square inch. Substitute 1 cm for 1 inch to find pixels per square centimeter or PPcm2.
What is cloud shadow?
A distant cloud casts its shadow across the sky. Cloud shadows, in effect the inverse of crepuscular rays, can produce some dramatic effects.
What is masking in remote sensing?
Masking is the process in which certain image parts are marked for exclusion from further analysis. Apart from clouds, the analysis intentions will help to determine which feature(s) to mask prior to image analysis.
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 is object size used in Google Earth?
Object size can be used as a mask condition to focus your analysis on objects of a certain size (e.g., mask out objects that are too small). Here the objectArea image calculated in the previous step is used as a mask to remove objects whose area are less than one hectare.
How are reducers used in Google Earth Engine?
You were first introduced to reducers for getting statistics in an image region. That was a spatial reduction. Reducing an image collection to an image is a temporal reduction when the collection represents images over time. The type of Reducer you use defines how Earth Engine handles overlapping pixels.
Are there any pixels over water in the mask?
As a result of this masking, all the pixels in the median composite that are over land (according to the Hansen et al. dataset) are visible, but those over water (or nodata) are transparent and will be excluded from any analysis you do on the maskedComposite image.