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How is output determined in Google Earth Engine?
Specifically, inputs are requested in the output projection. The output may be determined from a function parameter (e.g. crs ), the Map in the Code Editor (which has a maps mercator (EPSG:3857) projection), or with a reproject () call.
How are reprojections performed in Google Earth Engine?
The second reprojection is implicit, performed by Earth Engine automatically in order to display the result on the map. Also observe that the information about what projection to use propagates back from the request to the input. Figure 2. Flow chart of operations corresponding to the reprojection of a MODIS image in the Code Editor map.
What is a reference framework in Google Earth?
A reference framework consisting of a set of points, lines, and/or surfaces, and a set of rules, used to define the positions of points in space in either two or three dimensions. This tag also refers to cartographic projections and coordinate system transformations. Learn more… Shapefile not aligning with raster in Google Earth Engine?
How to normalize projection in Google Earth Engine?
When you display images in the Code Editor, inputs are requested in maps mercator. Consider the following simple operation on a MODIS image, which has a sinusoidal projection: // The input image has a SR-ORG:6974 (sinusoidal) projection. // Normalize the image and add it to the map.
What happens if you have too much data in Google Earth Engine?
If the scale you specified in the reproject () call is much smaller than the zoom level of the map, Earth Engine will request all the inputs at very small scale, over a very wide spatial extent. This can result in much too much data being requested at once and lead to an error.
Why does Google Earth Engine require a projection?
Only for output that’s ambiguous will Earth Engine require you to specify a projection and/or scale. Ambiguity can result from reducing an ImageCollection containing images with different projections (i.e. creating a composite ).
How does a reducer work in Google Earth?
As a result, the output image has the same number of bands as the input image; each band in the output is the reduction of pixels from the corresponding band in the input data. Some reducers take tuples of input datasets. These reducers will not be automatically replicated for each band.