To beat this, you need to learn how to resize images for the web. They can take a long time to load, which negatively impacts the user experience and your search engine rankings. But, those same images might be harming your site. They keep users engaged and make a website, blog post, banner ad, or email look professional. Java is a registered trademark of Oracle and/or its affiliates.Images are essential on the web. For details, see the Google Developers Site Policies. Learn more about how Earth Engine handles projections from theĮxcept as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. Map uses the maps mercator (EPSG:3857) projection, so theĪppropriate level of the image pyramid also needs to be reprojected prior to display. It is also worth noting that the Code Editor Zooming out far enough will not display the same pixels, but will insteadĭisplay higher levels of the image pyramid. The map starts zoomed all the way in, such that the native resolution pixels are clearly Consider the following simple example, which simply displays a Landsat When you visualize an image by adding it to the map, Earth Engine determines scale from You use a function which has a scale parameter. Note: To avoid ambiguity, always specify scale when The important point is that by varying the scale, different For similar scales, nearest neighbor resampling results in the same This is due to the fact that different pyramid levels are selectedįor different scales. In this example, note that the pixel value at a constant location (the image centroid) The scale determines the pyramid level from which to pull the input Print('Pixel value at '+scale+' meters scale', ForĮxample, using the NIR band of a Landsat image, which has 30 meters native resolution: Code Editor (JavaScript) var image = ee.Image('LANDSAT/LC08/C02/T1_TOA/LC08_044034_20140318').select('B4')

For other computations, you specify scale as an argument. The Code Editor determines the scale at which inputs are requested from the image For example, if youĪdd an image to the map with Map.addLayer(), the zoom level of the map in To request inputs to a computation is determined from the output. Scale of analysis in Earth Engine is determined on a 'pull' basis. The scale specified by your analysis and resamples (using nearest neighbor by default) When you use an image in your code,Įarth Engine chooses a level of the pyramid with the closest scale less than or equal to

The data are aggregated until theĮntire image fits within a 256x256 pixel tile. Pyramiding policy) to create higher pyramid levels. During ingestion, the data are aggregated (according to the The lowest level of the image pyramid represents image data at native resolution, when it is Pixel values of upper levels of the pyramid are a sample (usually the top left pixel) of The pyramid are the mean of pixels at the next lower level. For continuous valued images, the pixel values of upper levels of The pyramiding policy (represented by dashed lines in Figure 1) determines how each pixelĪt a given level of the pyramid is computed from the aggregation of a 2x2 block of pixelsĪt the next lower level. Image assets in Earth Engine exist at multiple scales, in EarthĮngine uses the scale specified by the output to determine the appropriate level of the A graphic representation of an image dataset in Earth Engine.ĭashed lines represent the pyramiding policy for aggregating 2x2 blocks of 4 pixels. Specifically, when you make a request for results, an image toĭisplay or a statistic, for example, you specify the scale at which data is input to theĪnalysis. GIS and image processing platforms, the scale of analysis is determined from the output,

Understanding how Earth Engine handles scale is crucial to interpreting scientific

Scale image