52 lines
2.0 KiB
JavaScript
52 lines
2.0 KiB
JavaScript
//Let's start with the calculation needed to create a band that shows pixels
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//where the Hansen et al. data show both loss and gain.
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//The Hansen et al. dataset has a band whose pixels are 1 where loss occurred
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//and 0 otherwise (loss) and a band that is 1 where gain has occurred and a 0 otherwise (gain).
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//To create a band where pixels in both the loss and the gain bands have a 1,
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//you can use the and() logical method on images. The and() method is called
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//like image1.and(image2) and returns an image in which pixels are 1 where both
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//image1 and image2 are 1, and 0 elsewhere:
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// Load the data and select the bands of interest.
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var gfc2014 = ee.Image("UMD/hansen/global_forest_change_2020_v1_8");
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var lossImage = gfc2014.select(['loss']);
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var gainImage = gfc2014.select(['gain']);
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// Use the and() method to create the lossAndGain image.
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var gainAndLoss = gainImage.and(lossImage);
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// Show the loss and gain image.
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Map.addLayer(gainAndLoss.updateMask(gainAndLoss),
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{palette: 'FF00FF'}, 'Gain and Loss');
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//Combining this example with the result from the previous section,
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//it's now possible to recreate the figure from the beginning of the tutorial:
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// Displaying forest, loss, gain, and pixels where both loss and gain occur.
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var gfc2014 = ee.Image('UMD/hansen/global_forest_change_2015');
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var lossImage = gfc2014.select(['loss']);
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var gainImage = gfc2014.select(['gain']);
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var treeCover = gfc2014.select(['treecover2000']);
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// Use the and() method to create the lossAndGain image.
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var gainAndLoss = gainImage.and(lossImage);
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// Add the tree cover layer in green.
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Map.addLayer(treeCover.updateMask(treeCover),
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{palette: ['000000', '00FF00'], max: 100}, 'Forest Cover');
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// Add the loss layer in red.
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Map.addLayer(lossImage.updateMask(lossImage),
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{palette: ['FF0000']}, 'Loss');
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// Add the gain layer in blue.
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Map.addLayer(gainImage.updateMask(gainImage),
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{palette: ['0000FF']}, 'Gain');
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// Show the loss and gain image.
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Map.addLayer(gainAndLoss.updateMask(gainAndLoss),
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{palette: 'FF00FF'}, 'Gain and Loss');
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