script.js

// Mapzen and Copernicus DEM difference Visualization
//VERSON = 3
function setup() {
    return {
      input: [
          {datasource: "map", bands:["DEM"]},
          {datasource: "cop", bands:["DEM"]}
          ],
      output: [
        {id: "default", bands: 3, sampleType: "UINT8"}
      ]
    };
  }
  
  function evaluatePixel(samples) {
    var map = samples.map[0];
    var cop = samples.cop[0];
    let d_dem = map.DEM - cop.DEM;
    const ramps = [
    [-300, [202, 0, 32]],
    [-100, [244, 128, 85]],
    [-40, [255, 160, 125]],
    [-10, [255, 211, 195]],
    [-5, [255, 255, 255]],
    [5, [255, 255, 255]],
    [10, [196, 209, 255]],
    [40, [155, 127, 255]],
    [100, [73, 98, 222]],
    [300, [8, 0, 176]]
    ];
    const visualizer = new ColorRampVisualizer(ramps);
    vis_dem = visualizer.process(d_dem);
    return {
      default: vis_dem
    };
  }