1. A method to update a data structure based on a plurality of parent data structures, at least one of the plurality of parent data structures associated with point data, the method comprising: receiving a notification to update from one of the plurality of parent data structures; determining that one or more of the plurality of parent data structures is updating; determining if a notification to update has been received from each of the one or more of the plurality of parent data structures; and if the notification to update has been received from each of the one or more of the plurality of parent data structures, updating the data structure based on data of the one or more of the plurality of parent data structures.