Added multiple scripts to ndsi page

Author: jonasViehweger

sentinel-2/ndsi-visualized/README.md

@@ -5,20 +5,30 @@ grand_parent: Sentinel
 layout: script
 permalink: /sentinel-2/ndsi/
 nav_exclude: true
+scripts:
+    - [Visualization, script.js]
+    - [EO Browser, eob.js]
+    - [Raw Values, raw.js]
 ---
 
+# TODO ADD CDSE LINK!
 
 ## Evaluate and visualize
- - [Sentinel Playground](https://apps.sentinel-hub.com/sentinel-playground/?source=S2&lat=40.39519549132737&lng=-3.739471435546875&zoom=11&preset=CUSTOM&layers=B01,B02,B03&maxcc=20&gain=1.0&gamma=1.0&time=2020-01-01%7C2020-07-13&atmFilter=&showDates=false&evalscript=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%3D%3D&evalscripturl=https://raw.githubusercontent.com/sentinel-hub/customScripts/master/sentinel-2/ndvi_uncertainty/script.js){:target="_blank"}    
- - [EO Browser](https://apps.sentinel-hub.com/eo-browser/?lat=46.4833&lng=14.2094&zoom=10&time=2019-10-23&preset=CUSTOM&datasource=Sentinel-2%20L1C&layers=B01,B02,B03&evalscript=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%3D%3D){:target="_blank"} 
+ - [EO Browser](https://sentinelshare.page.link/twxy){:target="_blank"} 
 
 
 ## General description of the script
 
 The Sentinel-2 normalized difference snow index is a ratio of two bands: one in the VIR (Band 3) and one in the SWIR (Band 11). Values above 0.42 are usually snow. More info [here.](https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm-overview){:target="_blank"}
 
+The Sentinel-2 normalised difference snow index can be used to differentiate between cloud and snow cover as snow absorbs in the short-wave infrared light, but reflects the visible light, whereas cloud is generally reflective in both wavelengths. In the visualization script snow cover is represented in bright vivid blue.
+
 ## Description of representative images
 
-The NDSI script applied to Klagenfurt, Austria. 
+Visualized NDSI over New Zealand, acquired on 2019-09-19. 
+
+![NDSI Visualized](fig/vis.png) 
+
+The NDSI script applied to Klagenfurt, Austria returning raw values. 
 
-![NDSI](fig/fig1.png) 
+![NDSI Raw](fig/raw.png) 

sentinel-2/ndsi-visualized/script.js

@@ -0,0 +1,40 @@
+//VERSION=3
+//Reference: https://earth.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm
+
+function setup() {
+    return {
+        input: ["B03", "B11", "B04", "B02", "dataMask"],
+        output: [
+            { id: "default", bands: 4 },
+            { id: "index", bands: 1, sampleType: "FLOAT32" },
+            { id: "eobrowserStats", bands: 2, sampleType: 'FLOAT32' },
+            { id: "dataMask", bands: 1 }
+        ]
+    };
+}
+
+function evaluatePixel(samples) {
+    let val = index(samples.B03, samples.B11);
+    let imgVals = null;
+    // The library for tiffs works well only if there is only one channel returned.
+    // So we encode the "no data" as NaN here and ignore NaNs on frontend.
+    const indexVal = samples.dataMask === 1 ? val : NaN;
+
+    if (val > 0.42)
+        imgVals = [0, 0.8, 1, samples.dataMask];
+    else
+        imgVals = [2.5 * samples.B04, 2.5 * samples.B03, 2.5 * samples.B02, samples.dataMask];
+
+    return {
+        default: imgVals,
+        index: [indexVal],
+        eobrowserStats: [val, isCloud(samples) ? 1 : 0],
+        dataMask: [samples.dataMask]
+    };
+}
+
+function isCloud(samples) {
+    const NGDR = index(samples.B03, samples.B04);
+    const bRatio = (samples.B03 - 0.175) / (0.39 - 0.175);
+    return bRatio > 1 || (bRatio > 0 && NGDR > 0);
+}

sentinel-2/ndsi/README.md

@@ -0,0 +1,16 @@
+//VERSION=3 (auto-converted from 1)
+
+// Normalised Difference Snow Index
+// Source: https://earth.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm
+// values above 0.42 are usually snow
+
+function setup() {
+  return {
+    input: ["B03", "B11"],
+    output: { bands: 1, sampleType: "FLOAT32" }
+  }
+}
+
+function evaluatePixel(samples) {
+  return [index(samples.B03, samples.B11)]
+}

sentinel-2/ndsi/eob.js

@@ -1,24 +1,20 @@
-//VERSION=3 (auto-converted from 1)
+//VERSION=3
+//Reference: https://earth.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm
 
-// Normalised Difference Snow Index
-// Source: https://earth.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm
-// values above 0.42 are usually snow
-
-let viz = new Identity();
+function setup() {
+  return {
+    input: ["B03", "B11", "B04", "B02", "dataMask"],
+    output: { bands: 4 }
+  };
+}
 
 function evaluatePixel(samples) {
-    let val = index(samples.B03, samples.B11);
-    return viz.process(val);
-}
+  let val = index(samples.B03, samples.B11);
 
-function setup() {
-  return {
-    input: [{
-      bands: [
-          "B03",
-          "B11"
-      ]
-    }],
-    output: { bands: 1 }
-  }
+  if (val > 0.42)
+    imgVals = [0, 0.8, 1, samples.dataMask];
+  else
+    imgVals = [2.5 * samples.B04, 2.5 * samples.B03, 2.5 * samples.B02, samples.dataMask];
+
+  return imgVals
 }

sentinel-2/ndsi/fig/fig1.png sentinel-2/ndsi/fig/raw.png

@@ -0,0 +1,20 @@
+//VERSION=3
+//Reference: https://earth.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm
+
+function setup() {
+  return {
+    input: ["B03", "B11", "B04", "B02", "dataMask"],
+    output: { bands: 4 }
+  };
+}
+
+function evaluatePixel(samples) {
+  let val = index(samples.B03, samples.B11);
+
+  if (val > 0.42)
+    imgVals = [0, 0.8, 1, samples.dataMask];
+  else
+    imgVals = [2.5 * samples.B04, 2.5 * samples.B03, 2.5 * samples.B02, samples.dataMask];
+
+  return imgVals
+}

sentinel-2/ndsi-visualized/fig/fig1.png sentinel-2/ndsi/fig/vis.png

@@ -11,5 +11,5 @@ function setup() {
 }
 
 function evaluatePixel(samples) {
-    return index(samples.B08, samples.B04)
+    return [index(samples.B08, samples.B04)]
 }

sentinel-2/ndsi/raw.js

@@ -13,5 +13,5 @@ function setup() {
 }
 
 function evaluatePixel(samples) {
-    return index(samples.B03, samples.B08);
+    return [index(samples.B03, samples.B08)]
 }

sentinel-2/ndsi/script.js

@@ -85,7 +85,7 @@ Dedicated to supplying data for [Copernicus services](https://www.esa.int/Our_Ac
  - [Snow classifier](/sentinel-2/snow_classifier/)
  - [Monthly snow report](/sentinel-2/monthly_snow_report)
  - [Snow cover change detection](/sentinel-2/snow_cover_change)
- - [NDSI Visualized](/sentinel-2/ndsi-visualized) - Visualized normalized difference snow index 
+ - [NDSI Visualized](/sentinel-2/ndsi) - Visualized normalized difference snow index 
 
 #### Disaster management and prevention algorithms
  - [Detecting deep moist convection](/sentinel-2/deep_moist_convection)