Urban detection with Sentinel-1 and Sentinel-2

//VERSION=3
//Author: Monja B. Šebela

function setup() {
  return {
    input: [
        {datasource: "S2L1C", bands:["B02", "B03", "B04", "B08", "B11"]},
        {datasource: "S1GRD", bands:["VV", "VH"], orthorectify:"TRUE"},
        {datasource: "S2L2A", bands:["B02", "B03", "B04"]}
    ],
    output: [
        { id: "default", bands: 3}
    ]
  };
}

function evaluatePixel(samples) {
 var S2L1C = samples.S2L1C[0]
 var S2L2A = samples.S2L2A[0]
 var S1 = samples.S1GRD[0]
 let ndvi = (S2L1C.B08 - S2L1C.B04) / (S2L1C.B08 + S2L1C.B04)
 let ndmi = (S2L1C.B08 - S2L1C.B11) / (S2L1C.B08 + S2L1C.B11)

   if (ndvi > 0.5) {
    return {
      default: [3*S2L2A.B04, 3*S2L2A.B03, 3*S2L2A.B02]
    }}
  if (ndmi > 0) {
    return {
      default: [3*S2L2A.B04, 3*S2L2A.B03, 4*S2L2A.B02]
    }
 }
  if ((S1.VH > 0.2)||(S1.VV > 0.2)) {
    return {
      default: [S1.VH*5.5, S1.VV, S1.VH*8]
    }}

  return {
    default: [3*S2L1C.B04-0.2, 3*S2L1C.B03-0.2, 3*S2L1C.B02-0.2]
  }
}

Author:

Monja B. Šebela

Evaluate and visualize

• EO Browser

General description of the script

This script is based on the Urban areas composite for Sentinel-1. The script displayes highly reflective VV and VH pixels as built up, limiting them by using basic vegetation and water masking with Sentinel-2. It is prone to overestimation over high slope areas and barren rock.

Description of representative images

Tabriz, Iran

Venice, Italy