SEDRIS Data Representation Model Content FAQ

Briefly describe the SEDRIS data representation model and how it is organized.

The SEDRIS data representation model (DRM) is based on an object-oriented notation comprised of concrete and abstract classes, and their relationships and attributes. Class-specific methods (or operations) are not supported. Relationships of various types (e.g., composition and association) are used to describe the hierarchical organizations of SEDRIS data objects meaningful to the M&S environmental modelers (e.g., spatial, thematic, or temporal). The primary SEDRIS DRM classes include: geometry, features, topology, textures and images, property grids plus data tables, and various libraries.

Why does SEDRIS show/contain a "tank" model within the data representation model? The submarine world doesn’t include targets or weapon systems as a part of the ocean environment.

There are significant sectors of the M&S Community where the external, 3-D features and characteristics of the vehicles encountered in the battlespace are critical to the simulation’s implementation. Because of the broad community use of this type of representational data, we made the decision to optionally include this data. Note that this is not behavioral or dynamic modeling data. It is only the data needed to represent the vehicle in the battlespace. Also note that a "tank" model is not really contained within the SEDRIS data representation model (DRM). What is contained in the SEDRIS DRM is a geometric union of polygons used to describe a geometry-model-instance that can be classified as a "tank" but there is no data element for "tank".

How does SEDRIS represent different items such as a tree or sound velocity profile (SVP)?

There are no tree or SVP classes specifically in the SEDRIS data representation model (DRM). There are entities in the DRM such as a point feature, a geometry, or a grid. Each entity is described by its attributes. With the appropriate attribute information, a point feature entity can represent a tree. A geometry entity can also represent a tree. With appropriate attribute information, a grid entity can represent an SVP. Along with location, the specific attributes place and elaborate the representation of a specific item within a synthetic environment.

What do environmental databases contain? Are they like a MircoSoft® Access database?

Although they are a collection of "things", environmental databases are not like MicroSoft® Access or other commercial relational databases. An environmental database contains data sets that represent the features of a synthetic environment for the purposes of simulation applications where both the presentation of the environmental scene and modeling of the environment’s effects on the participant/user's actions are desired. The data structures used in environmental databases are different than those used in relational databases. Therefore, the access methods for an environmental database must be specifically designed to operate on these unique structures.

Why are there many ways to organize objects in SEDRIS?

There are multiple data representational views and requirements, that have grown independently of one another in the M&S Community. SEDRIS provides the capability to express these different representations. The organization of the data within the data representation model is transparent to a consumer. Through the use of the APIs, the consumer extracts the data from the representational structure that meets their specific needs and then maps the data into their native database.

Return to: Top of this Page
Last updated: April 8, 1999