| SECTION 5 |
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5. Conventions and Guidelines
Section 5.1 presents USIGS conventions, and Section 5.2 presents USIGS guidelines.
5.1 USIGS Conventions
Interoperability cannot be achieved by the implementation of standards alone. It is necessary to augment the selected standards profile with USIGS-wide conventions for processes and procedures. A convention is a non-standardized but binding specification of practices typically used to maximize interoperability. This subsection defines an initial set of conventions for the USIGS. Candidate conventions are also discussed in this section. Conventions will continue to evolve as the USIGS is implemented. The conventions currently identified and discussed in this section are:
5.1.1 Naming Conventions for Directory and File Names
Conventions for directory and file naming are stipulated in the DII COE Integration and Run Time Specification (I&RTS) [I&RTS97]. The I&RTS describes the COE approach for a standardized disk directory structure for application software developed and implemented to comply with the segmentation guidelines of the I&RTS. The disk directory layout and file naming conventions are described in I&RTS Section 5.2. Additionally, the I&RTS also contains data store/file standards and guidance for physical storage of databases and data objects in Section 4.3.
5.1.2 Product Specifications and Standards
Appendix C of the UTA presents a list of NIMA product specifications and standards that document the format and content of NIMA generated products. These product specifications represent current methods and guidelines for developing MCG&I products that are primarily used with legacy systems. Any USIGS system that intends to produce a product contained on this list must meet the requirements specified in the product specification or standard for that product.
5.1.3 NITFS Bandwidth Compression Standards and Guidelines Document
This document (N-0106-97), dated 25 August 1998, defines the bandwidth compression standards, conventions and guidelines required for use by the National Imagery Transmission Format Standard (NITFS). It includes specifications on those standards, and implementation-related conventions and guidelines to improve interoperability of NITFS compressed files within the USIGS. The standards, conventions and guidelines defined in this document apply to the planning, development, test, evaluation and operation of imagery and geospatial systems that generate ("pack") or receive ("unpack") NITFS files within the USIGS environment. The use of this document is mandatory within the USIGS when the NITFS is being utilized.
Section 5 of this document defines Downsample JPEG Compression (NIMA Method 4). This approach provides a means to use existing lossy JPEG capabilities in the field to get increased compression for use with low bandwidth communications channels. NIMA Method 4 specifically correlates to a selection option (Q3) within downsample JPEG that provides a very usable tradeoff between file compression and the resulting loss in quality. Section 6 of the document outlines general requirements for NITFS compression.
A copy of this document can be found at: http://www.ismc.nima.mil.
5.1.4 USIGS Conceptual Data Model
The USIGS community relies heavily on the ability to exchange quality, seamlessly integrated, MCG&I information. The USIGS Conceptual Data Model (USIGS/CDM) facilitates this interoperability. The USIGS/CDM documents the data structures, meanings, and relationships for information requirements within the Imagery & Geospatial Community. It is the top layer of the three composing the model architecture; the other two being the Logical and Physical. The USIGS/CDM represents a high-level, precise, and unambiguous representation of MCG&I data and provides names, definitions, and structures for the conceptual elements within each functional area. The USIGS/CDM is composed of nine volumes comprising data models, relationships, entities, attributes, definitions, domains and other characteristics of data. The volumes are:
The DoD Directive 8320.1 directs DoD agencies to standardize data elements and established the Defense Data Dictionary System (DDDS). Data element submission and acceptance to the DDDS requires that the candidates be modeled. Many of the models and definitions in the USIGS/CDM are already in the Defense Data Dictionary Systems (DDDS) as approved standard data or in the review process leading to approval. The current DDDS status of each data entity and attribute is noted within the USIGS/CDM.
The use of the USIGS/CDM is mandatory within the USIGS in order to ensure effective and secure use of USIGS MCG&I information resources. Revision A, dated 23 June 1998, of the USIGS/CDM was released to support USIGS Effectivity 1.5. The USIGS modeling effort is a continual process and is dynamic; therefore expect the USIGS/CDM to be modified and re-released to support ongoing USIGS development programs.
The latest status and project information can be found at: http://www.nima.mil/aig/.
The USIGS/CDM is available on CD-ROM from the Systems Engineering & Integration Division (SOS), Engineering Branch (SOSE).
5.1.5 Mapping, Charting and Geodesy Accuracy
Department of Defense Standard Practice: Mapping, Charting & Geodesy Accuracy (MIL-STD-600001), 26 February 1990, defines Mapping, Charting and Geodesy (MC&G) product accuracy and provides a common basis for the appropriate application of these definitions. This standard practice is the convention to be used within the USIGS for both internal and contractual development efforts and to all levels involved in the maintenance of USIGS supported MC&G products.
5.1.6 Datums, Ellipsoids, Grids and Projections
NIMA Technical Manual: Datums, Ellipsoids, Grids, and Grid Reference Systems (NIMA TM 8358.1) defines the various grids, ellipsoids and datums to be used in the production of MC&G products. This manual is the convention to be used within the USIGS in support of the production of these products.
NIMA Technical Manual: The Universal Grids: Universal Transverse Mercator (UTM) and Universal Polar Stereographic (UPS) (NIMA TM 8358.2) describes the Universal Transverse Mercator and Universal Polar Stereographic projection systems. This manual is the convention to be used within the USIGS in support of the production of MC&G products.
Military Standard (DRAFT): Datums, Coordinates, and Grids for MC&G Applications (MIL-STD-2405) is a draft standard, prepared by NIMA, and has not been approved. It is subject to modification and therefore has not become an official NIMA or DoD standard. This considered to be an "emerging" convention and is not currently to be used for acquisition or other official purposes.
5.1.7 Core Video Metadata Profile
The Core Video Metadata Profile, Version 1.0, 14 March 1997, identifies a community-wide common set of video metadata that, when available, must be included in all Imagery & Geospatial Community (IGC) analog and digital video imagery signals. The near-term requirement to support current "analog video" in the IGC with a coordinated set of metadata was a significant factor in the selection of specific data elements in the profile. However, this profile also provides a stable foundation for metadata supporting digital video. As the IGC migrates from legacy analog applications to mostly digital video, the video metadata set will be modified to support data handling in the digital environment.
As part of the larger data standardization effort many of the elements correlate with data elements named and defined in the USIGS Conceptual Data Model (USIGS/CDM), Volume 3: Imagery. The Core Video Metadata Profile was designed to support current IGC needs including video archiving, exploitation, and dissemination; mapping and co-registration; and community-wide interoperability. Longer-term community requirements include the need for increased quality, accuracy, and additional video tools. Future requirements affecting the evolution of the Profile include the insertion of video into the entire IGC, expanding requirements to include tasking, collection, exploitation, reporting, product generation, and engineering studies and evaluations of video.
A copy of this specification can be found at: http://www.ismc.nima.mil.
5.2 USIGS Guidelines
USIGS Guidelines provide the final part of the framework to facilitate the successful implementation of the USIGS. Guidelines are not requirements for implementation, but rather constitute "recommended practices" among members of the USIGS community. Whenever possible, USIGS Guidelines will be aligned with the guidelines from larger communities, to which the USIGS belongs. The guidelines currently identified and discussed in this section are:
5.2.1 Guidelines for Server Names
Server names within the USIGS must be easily identifiable and accessible. Therefore, the names of servers are recommended to be in the form:
server type is a recognized server type within the USIGS. As the USIGS architecture evolves, additional servers will be specified. Examples include the Image Product Libraries (IPLs), the Command Information Libraries (CILs), and the National Information Library (NIL). The convention should be expanded to also include softcopy exploitation work group servers and others developed and implemented within USIGS.
site id is a an identifier that is unique to each site at which a USIGS server is deployed.
network-id is an identifier for a specific wide area, metropolitan area or local area network.
domain name is an organizational designation
The site id, network id, and domain name conventions are centrally managed for sensitive compartmented information (SCI) networks. The process for assigning these identifiers are contained in the Communications Systems Architecture for the INTELNET, dated 22 April 1997, and identifiers are registered and assigned through the Network Information Center (InterNIC).
An example notation of the IPL at NIMA's Washington Navy Yard Building 213 could be represented as:
5.2.2 Image Quality Guidelines
As part of NIMA's Technology Forecast effort, the Systems and Technology Directorate's Technology Office (ST/T) is working to update the United States Imagery System (USIS) Standards and Guidelines: Image Quality Guidelines [USIS95, Appendix IV]. These "guidelines are presented as suggestions which will minimize quality losses in the processing and presentation processes." These guidelines address both softcopy and hardcopy image quality.
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