Introduction to Scenes

Source file: scenes.htm

The scene is the central concept in Sentry. A scene comprises a series of scans arranged chronologically.

A scene is made up of as many as tens or hundreds of thousands of cells, which are clusters of raw scan points. While raw scan points may land in slightly different positions between scans, cells always represent the same regions of space throughout the time series. On this basis, the data within a cell can be meaningfully compared between scans at different points in time.

Although cells can be individually queried, the areas they represent are generally too small for direct analysis. Instead, the user defines zones around groups of cells that form regions of interest. A zone can be any size, from a single cell to a region encompassing the entire scanned area.

Zones are the basic elements of analysis in Sentry. Time-series data for each zone are represented in graphs (see Introduction to Graphs). Alarms can be triggered based on conditions met within a zone (see Alarms and Events > Defining monitoring alarms).

See also:  Scan points, cells and zones for the physical meanings of scan points, cells, and zones.

The measurement base is the reference scan in the time series against which data from the scan at each other time point is compared. Initially the measurement base is simply the first scan in the series, but it can be changed at any time to any scan or sequence of consecutive scans within the series. See Configuring for more information.

The scene origin is the origin of the first scan in the series. Subsequent scans may have origins that differ from the scene origin. A scene can be positioned or unpositioned. The origin of a positioned scene is at a known location (as provided by surveying or registration). All analyses are performed relative to the scene origin.