contour-demo-webscene.js

const webscene = new WebScene({
    ground: {
      opacity: 0 // set transparent ground
    }
});

const view = new SceneView({
    container: "viewDiv",
    map: webscene,
    qualityProfile: "high",
    viewingMode: "local",
    spatialReference: {
      wkid: 2056
    },
    camera: {
      position: { x: 2694307.39164, y: 1245619.17789, z: 100890.937, spatialReference: 2056 },
      heading: 0.00,
      tilt: 0.50
    },
    alphaCompositingEnabled: true, // enable transparent background
    environment: {
      background: {
        type: "color",
        color: [0, 0, 0, 0] // set background opacity to 0
      },
      starsEnabled: false,
      atmosphereEnabled: false
    },
    constraints: {
      altitude: {
        min: 5000,
        max: 100000
      }
    }
});