Cesium.js viewer for Oakland buildings

cesium-oakland.js

var viewer = new Cesium.Viewer('cesiumContainer', {timeline: false, animation: false});

var promise = Cesium.GeoJsonDataSource.load(
    'https://s3.amazonaws.com/jhurliman/oakland-building-footprints.geojson');

promise.then(function(dataSource) {
    viewer.dataSources.add(dataSource);
    
    // Get the array of buildings
    var entities = dataSource.entities.values;
    
    var colorHash = {};
    for (var i = 0; i < entities.length; i++) {
        var entity = entities[i];
        var type = entity.properties.bldgtype || '';
        var color = colorHash[type];
        if (!color) {
            color = Cesium.Color.fromRandom({ alpha: 1.0 });
            colorHash[type] = color;
        }

        entity.polygon.material = color;
        entity.polygon.outline = false;
        entity.polygon.extrudedHeight = getBuildingHeight(entity);
    }
});

var CENTER_LAT = 37.795024;
var CENTER_LON = -122.270031;

viewer.camera.lookAt(Cesium.Cartesian3.fromDegrees(CENTER_LON, CENTER_LAT),
                     new Cesium.Cartesian3(0, -4000, 4000));
viewer.camera.lookAtTransform(Cesium.Matrix4.IDENTITY);

function getBuildingHeight(entity) {
    var MAX_AREA = 10000; //852649.227299;
    var STOREY_HEIGHT = 3.5;
    
    var stories = entity.properties.nostory || 1;
    var area = entity.properties.shape_area || 0;
    
    return stories * STOREY_HEIGHT + Math.min(1, area / MAX_AREA) * STOREY_HEIGHT;
}