SEDRIS Real-Time Simulation FAQ

Can the STF format be used as a native format for a real-time aerial (and ground) simulation with no performance hit in comparison, for example, to running with OpenFlight or CTDB formats, or is the STF only a means to exchange data from different native terrain database formats such as OpenFlight and NIMA DTED?

STF was designed primarily as a file-based exchange format. The criteria for an exchange format are generally different than a run-time, real-time, or export format (each of these usually demands different designs).

Depending on the real-time requirements of an application, STF may or may not be suitable for such cases. There have been a few cases of past R&D projects where STF has been used (successfully) as the run-time format. But the majority of STF use has been exchange and data management cases.

Also, please note that there is usually a significant difference between run-time formats, such as CTDB, and export formats such as OpenFlight. To our knowledge, most uses of OpenFlight in run-time applications do not involve the use of OpenFlight as the run-time format, but rather there is a loader (converter) that converts the OpenFlight data to a given (usually graphic/scene graph) run-time format.

CTDB and other real-time (and run-time) formats, on the other hand, are specifically designed for run-time use, and utilize storage and retrieval features and capabilities that best help the applications for which they are designed. This sometimes includes significant trade-offs in other capabilities such as editing, database management, etc.

Some of the SEDRIS applications that have been developed (and are available via the SEDRIS web site) work directly with STF as their run-time format (the Focus application is a good example). Such applications are interactive, and users operate with the STF data in real-time. Such interaction includes manipulation of data, representation of data in 2D and 3D formats, etc.

However, if by real-time you mean that the STF is used as the rendering (visual) format, that is not the case. Please keep in mind, that in any graphics application, unless it is a custom-developed format and graphics hardware combination, the input formats for data are generally converted (on the fly or sometimes ahead of time) to the format that is used by the graphics hardware. Such conversions are usually driven by the choice of the graphics sub-systems (or their drivers) that are used.

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Last updated: February 26, 2003