A guide to SceneLayers
https://developers.arcgis.com/javascript/latest/guide/working-with-scene-layers/






scene layer at arcgis online
https://www.arcgis.com/home/search.html?start=1&sortOrder=desc&sortField=relevance&q=&focus=layers-weblayers-scenelayers&num=20






arcgis portal item id:  

// no url, only general info
https://www.arcgis.com/sharing/rest/content/items/7685f7ba6b47426ea20d6f640cf98596?f=json




// detailed url
https://www.arcgis.com/sharing/rest/content/items/7685f7ba6b47426ea20d6f640cf98596/data?f=json


                initialState: {environment: {lighting: {datetime: 1489607327000, displayUTCOffset: -8}},…}
                operationalLayers: [{id: "15a40f5cdf4-layer-8", opacity: 1, title: "Doors",…},…]
                0: {id: "15a40f5cdf4-layer-8", opacity: 1, title: "Doors",…}
                            id: "15a40f5cdf4-layer-8"
                            layerType: "ArcGISSceneServiceLayer"
                            opacity: 1
                            title: "Doors"
                            url: "http://services2.arcgis.com/z2tnIkrLQ2BRzr6P/ArcGIS/rest/services/CampusViewer_IndoorData/SceneServer/layers/0"
                            visibility: true

                1: {id: "15a40f4ab5c-layer-7", opacity: 1, title: "Walls",…}
                2: {id: "15a40f36e01-layer-6", opacity: 1, title: "Interior Space",…}
                3: {id: "15a40f2c5c9-layer-5", opacity: 1, title: "Building Wireframe",…}