DB update from DIS: This is the so-called “Dynamic TerrainSynthetic

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1. Raw source correlation: Is the degree of informational consistency between

two or more sets of raw data 18 i.e., inputs to a modeling station representing aspects of the same environment for instance, the correlation errors arising from Digital Terrain Elevation Data DTED elevation data that does not perfectly match to satellite raster imagery due to oblique view distortions induced by the satellite. Correlation errors are intrinsic to the process of gathering data because since there is no means to gather all of the required data from a single device, at a single instant in time. Instead, datasets e.g., elevation, raster imagery, geometry are each gathered from various devices of various types with distinct precision, formats, capabilities, fidelity at different times. This in turn leads to a broad range of correlation errors typically resolved by the modeler during the final assembly of the synthetic environment from its sources.

2. Source database self-correlation: Is the degree of informational consistency

between the internal datasets of a source database produced by a DB generation toolset. To a large extent, the effort expended at DB generation time consists in eliminating or at least reducing correlation errors arising from miss-correlated raw source data.

3. Runtime database correlation: Is the degree of informational consistency

between two or more runtime client-specific databases representing the same synthetic environment 19 . The likelihood of achieving correlated runtime client-device databases is particularly low when different authoring tools and possibly different source data are used to assemble each of the compiled runtime databases. In recent years, some authoring tools have been improved to automatically produce a set of client-device database from one common repository internal to the tools. Nonetheless, it is still current practice within the simulation community to independently deploy the simulator client-device databases; as a result, correlation errors may occur especially if the master database repository is constantly evolving. The CDB Specification eliminates database correlation errors since only one database is used to represent the same synthetic environment. The CDB is a single database that can be accessed simultaneously by all simulator client-devices at runtime. By definition, it addresses all runtime database-level correlation errors.

4. Numerical accuracy correlation: Is the degree of informational consistency

between the outputs of two or more devices, with each device performing the same algorithms, using the same control parameters but performing internal computations to a different numerical accuracy. Consider for example two 18 In this context, raw source denotes any input to the modeling workstation that is used to assemble the synthetic environment; consequently, the data may have undergone some level of post-processing such as image color- balancing, image ortho-rectification, etc. or may be in a specialized source interchange format such as SIF, SEDRIS, etc.. 19 A runtime client-specific database is a device-loadable database format that can be processed by a target device.