1. Status Update for Extended/Multiple Feature Data Dictionary CRP WP
101st OGC Technical Committee
Taichung, Taiwan
Sara Saeedi, University of Calgary
5 December 2016
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2. Copyright © 2016 Open Geospatial Consortium
Agenda
OGC CDB 1.0 Attribution and Extension
CDB Feature Data Dictionary
EFDD WP Objectives, Challenges and Future Plans
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3. CDB Attribution
Attributes are used to describe one or more real or virtual characteristics of a feature. Features can be assigned a variable number of attributes.
Attribute Code (e.g., the attribute "Angle of Orientation" has an attribute code of “0003”.)
Attribute Identifier (e.g., the CDB attribute "Length" has the “LEN” identifier. In the case of shapefile, the identifier is used as the name of the *.dbf column.)
Attribute Semantics (i.e., a human readable definition of the attribute.)
Attributes Values (Attribute values give quantitative/qualitative meaning to the attribute, such as the data type, length, format, range)
Attribute Usage (e.g., Mandatory, Recommended, Optional,Dependent)

4. CDB Attribution Extension
CDB Extended Attributes: attributes whose semantics, data type, usage, units, compatibility and schema are entirely governed by the CDB.
Geomatics Extended Attributes: Geomatics attributes are governed by various governmental/industrial specifications/standards found in source data that conforms to such specifications/standards. Geomatics standards (such as “DIGEST”, “NGA”)
Vendor Extended Attributes: governed by one or more vendors. In general, such attributes cannot be used by other vendors since they are often proprietary. (Vendors such as “CAE-M”, “Presagis”, “Thales”, “Rockwell”).
While the CDB itself does not define and govern the usage of the Geomatics and Vender attributes, it nonetheless accommodates their storage within a CDB.
CDB_Attributes.xml
Geomatics_Attributes.xml
Vendor_Attributes.xml

5. CDB Attribution Extension
The three attribution schemas supported by the CDB can be assigned to individual features and to groups of features:
Instance-level schema
Class-level schema
Extended-level schema
The CDB Specification offers three different attribution schemas. Each of the schemas offers different trade-offs in the manner attribution data is accessed and stored. Each of these schemas is largely motivated by the storage size considerations, and flexibility in the manner attribution data can be assigned to individual features and to groups of features.

6. CDB Attribution Extension - Vector Features
CEAI is the CDB Extended Attribute Index
GEAI and VEAI are for Geomatic and Vendor attributes
EAV is the attribute value string
Environment Attribute Code: a unique numeric code for each attribute type. The codes for the Geomatics and Vendor attributes are not specified by CDB. Instead, this Specification provides a metadata schema that allows developers to describe these attributes.

7. CDB XML and XSD (Schema Definitions)
XML is used to describe CDB metadata, to store global datasets, to add attributes to OpenFlight models, to describe base and composite materials, etc.
A schema is required to formally define the format of an XML file and to validate its content.
Together, these files provide all the information required to build the names of all directories permitted by the standard.
/CDB/Metadata/Lights.xml - CDB Lights
Defaults.xml - Default Read and Write values to be used by Simulator Client-Devices
Feature_Data_Dictionary.xml provides the list of directory names associated with FACC codes.
Moving_Model_Codes.xml provides the list of names for DIS Entity Kinds, Domains, and Categories.
DIS_Country_Codes.xml contains the list of DIS Country Names.
CDB_Attributes.xml, Vender_Attributes.xml, Geomatics_Attributes.xml , …
XML is used to describe CDB metadata, to store global datasets, to add attributes to OpenFlight models, to describe base and composite materials, etc.

8. What is CDB Feature Data Dictionary?
The CDB has an important Feature Data Dictionary (FDD) whose origins are traceable to the DIGEST v2.1 Specification. However, the current FDD is a consolidation of the DIGEST, DGIWG, SEDRIS, and UHRB dictionaries.
The CDB FDD makes use of FACC codes to classify features and an additional attribute called the FACC feature sub-code (FSC).

9. What is CDB Feature Data Dictionary?
FDD is provided in the form of an XML and XSD file in the Metadata Folder.
An XML Stylesheet is provided to format and display the dictionary inside a standard Web browser.
One of the uses of FACC feature codes by the Specification is to create a hierarchy of subdirectories by taking advantage of the manner in which a FACC is built. A FACC feature code is a 5-character code where the first character represents a category of features, the second represents a subcategory of the current category, and the last three characters represent a specific type in the subcategory.

10. Expansion of Feature Data Dictionary Work Package
Current Status:
The OGC CDB 1.0 accommodates the vast majority of attribution data that is in use today and available through formats and products supported by the DGIWG, NGA and other agencies. The feature attribution is based on the DIGEST (DGIWG), SEDRIS and UHRB geomatics standards.
These standards are commonly used for feature attribution of Vector data (RCS), GTModel Library, Moving model, Material and Light attribution data
The CDB provides the means to attribute features with attribution data with varied origins by using Geomatics and Vender attributes.

11. EFDD Work Package Objectives
The purposes of the EFDD Work Package Group are to
identify and resolve standardization and interoperability, backward compatibility, runtime-performance requirements related to multiple feature data dictionary, and attribute coding schemas
indicate what type of changes we need for EFDD: extensions, minor revisions, major revisions, or best practices?
define and import xml files for Geomatics Extended Attribute for data by one or more applications/origin such as DGWIG and NGA.
Some CDB folders have a hierarchy of subdirectories by taking advantage of FACC codes manners. This is used for organization and indexing. For backward compatibility, we need to define a methodology for CDB hierarchy (e.g. GTModel Library) to be independent from FACC and we can extend the current hierachy.

12. EFDD Work Package Challenges
How to support storage or usage of extended attribute or multiple FDD? Backward compatibility with CDB itself, CDB generation tools and CDB client-devices
If we have multiple or extended FDD, what is the performance changes in a CDB? Does CDB runtime implementation supports it?
The OGC CDB V1.0 provides a flexible means to tag features with attribution data.

13. \A_Category\B_Subcategory\999_Type\
Where A is the first character of the FACC code, Category is the category name, B is the second character of the FACC code, Subcategory is the subcategory name, 999 are the 3rd, 4th, and 5th characters of the FACC code, and Type feature type as per Appendix N.

14. CDB Moving Models make use of the DIS standard (see reference [7]) to create the directory structures where MModel datasets are stored. The DIS standard uses a structure called the DIS Entity Type to identify a “moving model”; this structure is made of seven fields named:
.\1_Kind\2_Domain\3_Country\4_Category\1_2_3_4_5_6_7\

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Future Plans
Initiating the WP and having bi-weekly meeting for WP
preparing and submitting Change Proposal Request (CPR)
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16. Thank You For Your Attention
Your feedback is appreciated
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