Snapshot
Snapshots and Snapshot Number
Although the monitored qualities are changing with time continuously, the software can only monitor them at discrete time spots. The wind is solved at discrete time steps as well. Note that the time step for solving the wind and the maximum time the wind is solved for are specified in the Entity Tree → Atmospheric Conditions → Wind → Model. The units are defined in seconds.
The term one Snapshot, represents a sample of the monitor data at a certain time step.
The following figure shows the relationship between the time step used for solving the wind and the sampling of the Monitor data – the generation of Snapshots. In this particular example, the solver solves the wind every 0.01 second (Time Step = 0.01s), meaning that it computes the wind data at 0.01s, 0.02s, 0.03s, ..., 99.97s, 99.98s, 99.99s, and 100s. However, the monitor only stores the wind data every second (Output Interval = 1.0s) (i.e., at 1s, 2s, 3s, ..., 98s, 99s, and 100s), therefore, this Monitor data will have 100 Snapshots, corresponding to the time steps at 1s, 2s, 3s, respectively.
![]() |
A number is assigned, the Snapshot Number, to each Snapshot in the Monitor data as its index in the whole set of Snapshots. For the above example, the software assigns 100 numbers, for example, 0, 1, 2, ..., 99, to these Snapshots respectively. At every level of the visualization tree, there is an item Snapshot that displays the current Snapshot being viewed.
Snapshot Synchronization
Since Virtualwind allows the Monitor data to be independently viewed on its individual quantities and by a variety of Actors, these quantities and Actors can show different Snapshots in parallel so their Snapshot numbers may be different.
Frequently, there is a need for making comparisons among quantities or Actors and you may want to make sure that all the Actors are rendering the same Snapshot. In this case, you can use the check boxes beside the items SynchronizeWithParent and SynchronizeChildren to force the group of interested Actors to render the same Snapshot.
As suggested by their names, the SynchronizeWithParent check box is used to set the Snapshot used by all the items at the current level of the tree to the same one used by their parent and the SynchronizeChildren is used to let all its children items to use the same Snapshot as the one it is using. Once they are checked, all the affected Actors will automatically update their rendering to show the correct Snapshot.