False color visualization for Sentinel-1
// Sentinel-1 False-Color Visualization V1.0.0
// Twitter: Pierre Markuse (@pierre_markuse)
// Website: https://pierre-markuse.net/
// CC BY 4.0 International - https://creativecommons.org/licenses/by/4.0/
function stretch(val, min, max) {
return (val - min) / (max - min);
}
function satEnh(rgbArr) {
var avg = rgbArr.reduce((a, b) => a + b, 0) / rgbArr.length;
return rgbArr.map(a => avg * (1 - saturation) + a * saturation);
}
var BLUE = [0.0, 0.2, 1.0];
var GREEN = [0.0, 0.7, 0.0];
var BLACK = [0.0, 0.0, 0.0];
var RED = [1.0, 0.0, 0.0];
var water_normal = [stretch(VV*1,0.0,0.99),stretch(VV*8,0.0,0.99),0.5+VV*3+stretch(VH*2000,0.0,0.99)];
var water_bright = [stretch(VV*1.33,0.0,0.99),stretch(VV*10,0.0,0.99),0.5+VV*4+stretch(VH*3000,0.0,0.99)];
var oilspill_1 = [stretch(VV*5.0,0.2,0.99),0.0+stretch(VV*10,0.10,0.50),0.0+stretch(VV*20,0.10,0.50)];
var oilspill_2 = [stretch(VV*5.0,0.2,0.99),0.0+stretch(VV*10,0.15,0.40),0.1+stretch(VV*20,0.15,0.40)];
var oilspill_3 = [stretch(VV*5.0,0.2,0.99),0.1+stretch(VV*11,0.03,0.60),0.1+stretch(VV*23,0.01,0.58)];
var land_redder = [stretch(VV*3.4,-0.0,0.99),(stretch(VV*1.1,-0.0,0.99)+stretch(VH*8.75,-0.0,0.99)),stretch(VH*1.75,-0.0,0.99)];
var land_normal = [stretch(VV*3.0,-0.0,0.99),(stretch(VV*1.1,-0.0,0.99)+stretch(VH*8.75,-0.0,0.99)),stretch(VH*1.75,-0.0,0.99)];
var land_greener = [stretch(VV*3.0,-0.0,0.99),(stretch(VV*1.4,-0.0,0.99)+stretch(VH*9.75,-0.0,0.99)),stretch(VH*1.75,-0.0,0.99)];
var city = [0.9-VV-2*VH,0.9-VV-3*VH,0.9-0.3*VV-6*VH];
var watervis = water_normal;
var landvis = land_normal;
var water_threshold = 25; //lower means more water
var saturation = 1.0; //Standard 1.0
var brightness = 1.0; //Standard 1.0
var avoid_dark_land = 0; //0=off,1=on
var avoid_dark_land_threshold = 0.1; //Standard 0.05
var avoid_dark_water = 0; //0=off,1=on
var avoid_dark_water_threshold = 1.00; //Standard 1.00
var manualCorrection_water = [0.00, 0.00, 0.00];
var manualCorrection_land = [0.00, 0.00, 0.00];
var i = 0;
while (i<3) {
watervis[i] = watervis[i] + manualCorrection_water[i];
landvis[i] = landvis[i] + manualCorrection_land[i];
landvis[i] = landvis[i] * brightness;
i++;
};
var watervis = satEnh(watervis);
var landvis = satEnh(landvis);
if (avoid_dark_land) {
var dark = landvis[0]+landvis[1]+landvis[2];
if (dark < avoid_dark_land_threshold) {var landvis=BLUE;}; //Try other things than BLUE!
};
if (avoid_dark_water) {
var dark = watervis[0]+watervis[1]+watervis[2];
if (dark < avoid_dark_water_threshold) {var watervis=BLUE;}; //Try other things than BLUE!
};
return ((VV/VH) > water_threshold)
? watervis :
landvis;Evaluate and Visualize
Description
This script offers different false color visualizations and the ability to easily add more visualizations. Variables allow you to influence the resulting image regarding the content you would like to point out.
More info here.
Description of representative images
Grand Bahama Island Sentinel-1 SAR image
