added ws202425 courses

2022_Spezielle_Themen_der_Fernerkundung/02_SRTM-terrain.js

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+// Calculate slope and aspect
+// Calculate statistics
+
+//Detailed description: https://developers.google.com/earth-engine/tutorial_api_03
+
+// Load the SRTM image.
+var srtm = ee.Image('CGIAR/SRTM90_V4');
+
+// Apply an algorithm to an image.
+var slope = ee.Terrain.slope(srtm);
+
+print(slope)
+// Convert degree in percent
+
+// Display the result.
+Map.setCenter(12.978717025594149,47.55544193154224,11); // Center on Königsee.
+Map.addLayer(srtm, {min: 0, max :2500}, 'srtm');
+Map.addLayer(slope, {min: 0, max :60}, 'slope');
+
+
+//Image math
+// Get the aspect (in degrees).
+var aspect = ee.Terrain.aspect(srtm);
+// Convert to radians, compute the sin of the aspect.
+var sinImage = aspect.divide(180).multiply(Math.PI).sin();
+// Display the result.
+Map.addLayer(sinImage, {min: -1, max: 1}, 'sin');
+
+
+
+// Image statistics
+// Compute the mean elevation in the polygon.
+var stddevDict = srtm.reduceRegion({
+  reducer: ee.Reducer.stdDev(),
+  geometry: koenigsee,
+  scale: 90
+});
+
+// Print dictionary
+print("dict", stddevDict)
+
+// Get the mean from the dictionary and print it.
+// In java a dictionary is a collection of different kinds of information.
+// In other languages such as R a dictionary is usally named 'object'.
+
+var stddev = stddevDict.get('elevation');
+print('stdDev elevation', stddev);
+