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structured data store supports other file types. For example, an OGC GeoPackage file could be stored in the CDB structure. However, a compliance test may throw an exception stating that the
GeoPackage file type is not recognized.
The CDB standard permits any CDB to run “as-is”, without any offline assembly aka compilation, translation, conversion, on any CDB-compliant simulator client-device platform.
This allows the simulator user community AND the database creation community to freely exchange CDBs across simulators and database generation facilities either through the exchange
of physical media or entire storage subsystems or via network. As a result, a CDB structured data store can be run and exchanged without change on any CDB-compliant simulator client-
devices or any database generation workstations, regardless of the computer platforms, simulator system software.
The storage structure of the CDB standard allows for efficient searching, retrieval and storage of any information contained within the data store. The storage structure portion of the CDB data
model is defined in Chapter 3.
The formats currently used in a CDB compliant data stpres are:
1. TIFF .tif: used for the representation of all datasets whose inherent structure
reflects that of a two-dimensional regular grid in a Cartesian coordinate system. The primary use of TIFF within a CDB conformat data store is for the representation of
terrain elevation and raster imagery. To qualify as a CDB-compliant TIFF reader, the reader must satisfy the requirements described in Clause 8 of Volume 10: OGC CDB
Implementation Guidance. Please note that the LZW compression algorithm within the TIFF format is supported and encouraged by the CDB standard when the data type of the
content of the file is of integral type. As a consequence, it is strongly recommended to compress TIFF files containing integer values but to avoid compression if the file
contains floating-point values.
2. GeoTIFF .tif: used for the representation of all datasets whose inherent structure
reflects that of a two-dimensional regular grid of a Geographic coordinate system. The primary use of GeoTIFF within a CDB data store is for the representation of terrain
elevation note: the use GeoTIFF is preferred over TIFF in the case of terrain elevation. CDB-compliant GeoTIFF readers do not concern themselves with any of the GeoTIFF
specific tags because the CDB standard provides all of the conventions to geo-reference each geographic dataset. However, it is strongly recommended that data store generation
tools be fully compliant to GeoTIFF; this provision eliminates the need for the tools to be aware of the CDB conventions governing the content of each geo-referenced dataset.
3. SGI Format .rgb: used for the representation of 3D model textures. The file format
allows for the representation of an image with 1, 2, 3, or 4 channels. A single channel image represents a grey-shaded texture; a two-channel image represents a grey-shaded
texture with an alpha component providing the transparency; a three-channel image represents a color RGB texture; finally, a four-channel image is a color RGB texture
with an alpha channel providing the transparency. CDB-compliant RGB readers must be
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fully compliant with the SGI Image File Format Specification. Its use is limited to 3D models.
4. JPEG 2000 .jp2: used for the representation of an image encoded in accordance to
