Add FLIR visualisation for Landsat-8 (#329)

* Add EOB script for FLIR vis

* Raw thermal band in celsius

* Add link in Landsat page

* Add readme

* Add visualisation script

* Add example image

Author: maximlamare

landsat-8/landsat-8.md

@@ -40,4 +40,5 @@ The Landsat program is the longest running enterprise for acquisition of satelli
   - [Clouds Segmentation](/landsat-8/clouds_segmentation)
   - [Pansharpened true color](/landsat-8/true-color-pansharpened)
   - [Thermal visualization](/landsat-8/thermal)
+  - [Thermal FLIR visualization](/landsat-8/thermal-iron)
   - [Band quality assessment band visualization](/landsat-8/bqa)

landsat-8/thermal-iron/README.md

@@ -0,0 +1,46 @@
+---
+title: FLIR visualisation of the thermal IR band
+parent: Landsat-8
+grand_parent: Landsat
+layout: script
+permalink: /landsat-8/thermal-iron/
+nav_exclude: true
+scripts:
+- - Visualization
+  - script.js
+- - EO Browser
+  - eob.js
+- - Raw Values
+  - raw.js
+examples:
+- zoom: '11'
+  lat: '35.18167'
+  lng: '-5.4657'
+  datasetId: AWS_LOTL2
+  fromTime: '2024-07-15T00:00:00.000Z'
+  toTime: '2024-07-15T23:59:59.999Z'
+  platform:
+  - EOB
+  evalscripturl: https://custom-scripts.sentinel-hub.com/custom-scripts/landsat-8/thermal-iron/eob.js
+---
+## General description
+
+Since the inception of thermal imaging, infrared cameras have commonly employed a distinctive color palette, ranging from black to blue, magenta, orange, yellow, and culminating in bright white. This palette is frequently referred to as “Iron” or “Ironbow.” 
+
+This script allows the visualisation of the thermal IR band of Landsat 8 (Band 10, centered on 10.895 µm) in a FLIR-like palette that was inspired by a StackOverflow post [1]. The script allows the adjustment of 3 parameters:
+
+- **minValue**: The minimum value of the thermal band mapped to the black color.
+- **maxValue**: The maximum value of the thermal band mapped to the white color.
+- **numSteps**: The number of increments in the color palette.
+
+The script returns the thermal band values in degrees Celsius, converted from Kelvin, for an easier interpretation. Furthermore, the script masks out clouds and cloud shadows using the QA band (BQA).
+
+## Description of representative images
+
+Thermal data over Morocco. Acquired on 15.07.2024.
+
+![Morocco thermal image](fig/fig1.png)
+
+
+## References
+ [1] StackOverflow, [Thermal imaging palette](https://stackoverflow.com/questions/28495390/thermal-imaging-palette). Accessed on 19th September 2024.

landsat-8/thermal-iron/eob.js

@@ -0,0 +1,71 @@
+//VERSION=3 
+
+// Set Min and Max values for display and number of steps in the palette
+const minValue = 10
+const maxValue = 45
+const numSteps = 200
+
+// Setup palette
+const palette_colours = palette(numSteps, minValue, maxValue)
+const viz = new ColorRampVisualizer(palette_colours);
+
+
+function setup() {
+  return {
+    input: ["B10", "BQA", "dataMask"],
+    output: [
+      { id: "default", bands: 4 },
+      { id: "eobrowserStats", bands: 2 },
+      { id: "dataMask", bands: 1 },
+    ],
+  };
+}
+
+function evaluatePixel(samples) {
+  let val = samples.B10 - 273;
+  let clouds = isCloud(samples)
+  
+  return {
+    default: [...viz.process(val), (samples.dataMask * (clouds ? 0 : 1))],
+    eobrowserStats: [val, clouds ? 0 : 1],
+    dataMask: [samples.dataMask],
+  };
+}
+
+function isCloud(sample) {
+  const BQA = decodeL8C2Qa(sample.BQA);
+  let cloudPresence = false
+  if (BQA.cloud == 1 || BQA.cloudShadow == 1 || BQA.cirrus == 1 || BQA.dilatedCloud == 1) {
+    cloudPresence = true 
+  }
+  return cloudPresence
+}
+
+function componentToHex(c) {
+    var hex = c.toString(16);
+    return hex.length == 1 ? "0" + hex : hex;
+  }
+  
+  function rgbToHex(r, g, b) {
+    return "0x" + componentToHex(r) + componentToHex(g) + componentToHex(b);
+  }
+
+function palette(colour_length, min_value, max_value){
+    let colourPairs = []
+    let values = Array.from({length: colour_length}, (_, i) => min_value + (max_value - min_value) * i / (colour_length - 1));
+    for (var idx = 0; idx < colour_length; idx++){
+        var x = idx * 1.0/colour_length;
+        
+        // Convert RGB to hex
+        let coulours = rgbToHex(Math.round(255*Math.sqrt(x)), 
+                        Math.round(255*Math.pow(x,3)), 
+                        Math.round(255*(Math.sin(2 * Math.PI * x)>=0?
+                                      Math.sin(2 * Math.PI * x) :
+                                      0 )))
+        
+        //Make pairs of colours
+        colourPairs.push([values[idx], coulours.toString()])
+       
+    }
+    return colourPairs
+}

landsat-8/thermal-iron/fig/fig1.png

@@ -0,0 +1,16 @@
+//VERSION=3 
+
+function setup() {
+  return {
+    input: ["B10"],
+    output: {
+      bands: 1,
+      sampleType: "FLOAT32"
+    }
+  };
+}
+
+function evaluatePixel(samples) {
+  // Convert to Celsius
+  return [samples.B10 - 273];
+}

landsat-8/thermal-iron/raw.js

@@ -0,0 +1,65 @@
+//VERSION=3 
+
+// Set Min and Max values for display and number of steps in the palette
+const minValue = 10
+const maxValue = 45
+const numSteps = 200
+
+// Setup palette
+const palette_colours = palette(numSteps, minValue, maxValue)
+const viz = new ColorRampVisualizer(palette_colours);
+
+
+function setup() {
+  return {
+    input: ["B10", "BQA", "dataMask"],
+    output: {
+      bands: 4
+    }
+}
+}
+
+function evaluatePixel(samples) {
+  let val = samples.B10 - 273;
+  let clouds = isCloud(samples)
+  
+  return [...viz.process(val), (samples.dataMask * (clouds ? 0 : 1))];
+}
+
+function isCloud(sample) {
+  const BQA = decodeL8C2Qa(sample.BQA);
+  let cloudPresence = false
+  if (BQA.cloud == 1 || BQA.cloudShadow == 1 || BQA.cirrus == 1 || BQA.dilatedCloud == 1) {
+    cloudPresence = true 
+  }
+  return cloudPresence
+}
+
+function componentToHex(c) {
+    var hex = c.toString(16);
+    return hex.length == 1 ? "0" + hex : hex;
+  }
+  
+  function rgbToHex(r, g, b) {
+    return "0x" + componentToHex(r) + componentToHex(g) + componentToHex(b);
+  }
+
+function palette(colour_length, min_value, max_value){
+    let colourPairs = []
+    let values = Array.from({length: colour_length}, (_, i) => min_value + (max_value - min_value) * i / (colour_length - 1));
+    for (var idx = 0; idx < colour_length; idx++){
+        var x = idx * 1.0/colour_length;
+        
+        // Convert RGB to hex
+        let coulours = rgbToHex(Math.round(255*Math.sqrt(x)), 
+                        Math.round(255*Math.pow(x,3)), 
+                        Math.round(255*(Math.sin(2 * Math.PI * x)>=0?
+                                      Math.sin(2 * Math.PI * x) :
+                                      0 )))
+        
+        //Make pairs of colours
+        colourPairs.push([values[idx], coulours.toString()])
+       
+    }
+    return colourPairs
+}