function init() {
    // Create the main viewer.
    var viewer = new ROS3D.Viewer({
        divID: 'radar_markers',
        background: '#707070',
        width: 650,
        height: 650,
        antialias: true,
        displayPanAndZoomFrame: false
    });

    // Setup a client to listen to TFs.
    var tfClient = new ROSLIB.TFClient({
        ros: ros,
        angularThres: 0.01,
        transThres: 0.01,
        rate: 100.0,
        fixedFrame: '/rslidar'
    });

    var gridClient = new ROS3D.Grid({
        num_cells: 20
    });
    var axesClient = new ROS3D.Axes({
    });

    viewer.addObject(gridClient);
    viewer.addObject(axesClient);

    var markerArrayClient1 = new ROS3D.MarkerArrayClient({
        ros: ros,
        tfClient: tfClient,
        topic: '/vis_s1_objects',
        rootObject: viewer.scene
    });

    var markerArrayClient2 = new ROS3D.MarkerArrayClient({
        ros: ros,
        tfClient: tfClient,
        topic: '/vis_s2_objects',
        rootObject: viewer.scene
    });
    var markerArrayClient3 = new ROS3D.MarkerArrayClient({
        ros: ros,
        tfClient: tfClient,
        topic: '/vis_s3_objects',
        rootObject: viewer.scene
    });
}

processMessage(arrayMessage) {
  arrayMessage.markers.forEach(function(message) {
      var key = message.ns + message.id;
      if (message.action === 0) {
          var updated = false;
          if (key in this.markers) { // "MODIFY"
              updated = this.markers[key].children[0].update(message);
              if (!updated) { // "REMOVE"
                  this.removeMarker(key);
              }
          }
          if (!updated) { // "ADD"
              var newMarker = new Marker({
                  message: message,
                  path: this.path,
              });
              this.markers[key] = new SceneNode({
                  frameID: message.header.frame_id,
                  tfClient: this.tfClient,
                  object: newMarker
              });
              this.rootObject.add(this.markers[key]);
          }
      } else if (message.action === 1) { // "DEPRECATED"
          console.warn('Received marker message with deprecated action identifier "1"');
      } else if (message.action === 2) { // "DELETE"
          this.removeMarker(key);
      } else if (message.action === 3) { // "DELETE ALL"
          for (var m in this.markers) {
              this.removeMarker(m);
          }
          this.markers = {};
      } else {
          console.warn('Received marker message with unknown action identifier "' + message.action + '"');
      }
  }.bind(this));