Global Surface Water Transitions visualisation script 

//VERSION=3

//This custom script visualises the transitions layer according to the data user guide.

//Set up input and output settings
function setup() {
  return {
    input: ["transitions"],
    output: {
      bands: 3,
      sampleType: "AUTO"
    }
  }
}

//Create discrete color map
const map = [
  [0, 0xffffff],    // Not water (White)
  [1, 0x0000ff],    // Permanent (Pure blue)
  [2, 0x22b14c],    // New permanent (Dark cyan - lime green)
  [3, 0xd1102d],    // Lost permanent (Strong red)
  [4, 0x99d9ea],    // Seasonal (Very soft cyan)
  [5, 0xb5e61d],    // New seasonal (Vivid yellow)
  [6, 0xe6a1aa],    // Lost seasonal (Very soft red)
  [7, 0xff7f27],    // Seasonal to permanent (Vivid orange)
  [8, 0xffc90e],    // Permanent to seasonal (Vivid yellow)
  [9, 0x7f7f7f],    // Ephemeral permanent (Dark gray)
  [10, 0xc3c3c3],   // Ephemeral seasonal (Light gray)
  [255, 0xcccccc]   // No data (Light gray)
];

//Create visualizer
const visualizer = new ColorMapVisualizer(map);

//EvaluatePixel function
function evaluatePixel(sample) {
  return [visualizer.process(sample.transitions)[0], visualizer.process(sample.transitions)[1], visualizer.process(sample.transitions)[2]];
}

General description of the script

This script visualizes the Transitions layer from the Global Surface Water dataset according to the official symbology (Table 1). The Transitions layer is derived from a seasonality comparison between the first and last year of the entire time period and visualises changes in the three surface water classes of not water, seasonal, and permanent water.

Table 1: Transitions Symbology

Value Symbol Colour Label
0 0xffffff Not water
1 0x0000ff Permanent
2 0x22b14c New permanent
3 0xd1102d Lost permanent
4 0x99d9ea Seasonal
5 0xb5e61d New seasonal
6 0xe6a1aa Lost seasonal
7 0xff7f27 Seasonal to permanent
8 0xffc90e Permanent to seasonal
9 0x7f7f7f Ephemeral permanent
10 0xc3c3c3 Ephemeral seasonal
255 0xcccccc No data


Description of representative images

EO Browser visualisation of the Transitions layer showing the Paraná River near santa Fe, Argentina.

Transitions Paraná River near Santa Fe in Argentina

Resources