Appendix A: MCG&I Domain Services

While the USIGS will invoke components that are defined for many information domains, the domain of greatest interest to USIGS planners, implementers, and users is, clearly, the MCG&I domain.

The MCG&I domain services architecture identifies the services required for the building of MCG&I applications. This appendix addresses the conceptual structure of the MCG&I domain services architecture and outlines the categories of services, and their interfaces, that are required to populate that architecture. The services have been grouped into service categories which, in some cases, are grouped into service categories of a broader nature. The service category groupings are based upon the anticipation that the services within each service category will:

In essence, the MCG&I domain services architecture provides a structure for ensuring that all of the appropriate objects and methods are defined. Implementation specifications, that serve to define the syntax and semantics of the services identified herein, may be structured differently in order to depict the processing interdependencies that exist across categories. Actual implementations are expected to differ as well, since all MCG&I applications will not use all MCG&I services, nor will they be restricted to MCG&I services and, therefore, may be grouped differently.

A.1 Consensus MCG&I Domain Architecture

The Open GIS Consortium, Inc. (OGC) (for more information on the OGC, please see their WWW page at http://www.opengis.org/) is in the process of defining an object-based architecture for geospatial services and structures. OGC's Open GIS Service Architecture has been designed in cooperation with the design of the USIGS MCG&I domain services architecture, so there are few significant differences between them. The following paragraphs discuss those service categories and services of that architecture.

Throughout this appendix, there are figures that show the USIGS MCG&I domain services and Open GIS Service Architecture components. The intent is to illustrate the cooperation and dialog that has been developed between NIMA and the OGC in aligning their architectures. At the time of this writing, this was an ongoing process, so both models are expected to progress with the highest possible level of commonality.

A.2 MCG&I Domain Service Categories

A.2.1 Geospatial Domain Access Services

Geospatial Domain Access Services (GDAS) defines a set of interfaces for locating and retrieving selected MCG&I information for storage, deletion, or modification. Geospatial Domain Access Services include:

Figure A-1 illustrates the USIGS technical architecture elements related to the GDAS.

Figure A-1. USIGS Geospatial Domain Access Services

A.2.1.1 Geospatial Information Access Services

Geospatial Information Access Services comprise three specific service categories:

A. Geospatial Information Storage and Retrieval Services

Geospatial Information Retrieval Services provide services for MCG&I information storage and retrieval for the purposes of deletion, modification, and/or display. Geospatial Information Retrieval Services are intended primarily for client storage and retrieval of geospatially referenced information of all kinds to/from a library (data server) that may be remotely located relative to the client. The Geospatial Information Retrieval Services provide for the following basic capabilities:

A. Geospatial Information Catalog Services

The Geospatial Information Catalog Services provide a set of common services to support both local and global MCG&I information discovery, property (metadata) retrieval, MCG&I information browsing, and MCG&I information cataloging and indexing. Types of retrieval that are required include:

A. Geospatial Product Information Service

The Geospatial Product Information Service provides for the retrieval and storage of whole products (predefined feature collections and metadata subsets) and allows the client to retrieve some properties specifically associated with an object without going to the catalog. The Geospatial Product Information Service provides for robust references to arbitrary information products in a distributed environment through the use of library location information and file path names. Since the product reference is expected to contain all of the necessary information for retrieval, distributed processing can be handled transparently. The product references are specialized in the Geospatial Product Information Service for use by libraries and include support for parameters. This service is equivalent to having a paper map or preprinted image, in that the boundaries and content of the information are known before the information is requested. This capability is of particular use in the dissemination of reports and the like for which all recipients or requesters are not previously known. In an electronic environment, it provides the capability to predefine an MCG&I component of a web page, for instance.

A.2.1.2 Geospatial Dissemination Services

Geospatial Dissemination Services include the interfaces required to receive, prepare (i.e., reformat, compress, decompress, etc.), prioritize, and transmit MCG&I information that has been requested by a client through standing queries or profiles. They also include interfaces to support product distribution management and to enable dissemination of MCG&I information to third parties. This is strictly a batch-like capability that is expected to use the Geospatial Information Access Services and the Geospatial Information Packaging Services as components. Operationally, it is expected that this component would be invoked by a library resident event handler. Invocation would occur at the time a message containing new information is received by the library and processed for storage therein. At that time, the Geospatial Dissemination Services would check its repository of standing queries for those that are satisfied by the new information, make appropriate modifications to the information's structure and format, and transmit the information to the recipients indicated by the standing query.

A.2.1.3 Geospatial Information Packaging Services

Geospatial Information Packaging Services are composed of three service categories:

A. Feature Compression Service

The Feature Compression Service provides for conversion of vector and gridded portions of a feature collection to and from compressed form.

A. Image Compression Service

The Image Compression Service provides for conversion of an image to and from compressed form.

A. Geospatial Information Transfer Service

Geospatial Information Transfer Services are those required to build, access and manipulate the fundamental units and collections of MCG&I information to be transferred between MCG&I Domain-compliant application services in fulfilling their users' requests.

A.2.2 Feature Generalization Services

The Feature Generalization Services (FGS), shown in Figure A-2, are a category of services that modify the characteristics of a feature collection to increase the effectiveness of communication by counteracting the undesirable effects of data reduction. These services include capabilities to:

Figure A-2. USIGS Feature Generalization Services

A.2.3 Geospatial Information Extraction Services

Geospatial Information Extraction Services (GIES), shown in Figure A-3, are a category of services that support the extraction of feature and terrain information from remotely sensed and scanned images. These services include capabilities to:

Figure A-3. USIGS Geospatial Information Extraction Services

A.2.4 Geospatial Coordinate Transformation Services

Geospatial Coordinate Transformation Services (GCTS), shown in Figure A-4, comprise capabilities for converting geospatial coordinates from one reference system to another. This includes the ability to:

Figure A-4. USIGS Geospatial Coordinate Transformation Services

A.2.5 Geospatial Annotation Services

Geospatial Annotation Services (GAS), shown in Figure A-5, add ancillary information to an image or a feature in a Feature Collection (e.g., by way of a label, a hot link, or an entry of a property for a feature into a database) that augments it or makes it more complete.

The Image Annotation Services provides for standard interfaces to software tools that enable symbols, graphics, text, and other media types to be overlaid upon, or attached to, images to highlight significant content. Capabilities of this service will include:

Similarly, the Feature Annotation Services provides for the capability to add ancillary information to a feature in a Feature Collection (e.g., by way of a label, a hot link, or an entry of an attribute for a feature into a database) that augments or provides a more complete description of the feature.

Figure A-5. USIGS Geospatial Annotation Services

A.2.6 Imagery Manipulation Services

Imagery Manipulation Services (IMS), shown in Figure A-6, provide for manipulating images (resizing, changing color and contrast values, applying various filters, manipulating image resolution, etc.) and for conducting mathematical analyses of image characteristics (computing image histograms, convolutions, etc.). These services include services to:

Figure A-6. USIGS Imagery Manipulation Services

A.2.7 Geospatial Feature Manipulation Services

Geospatial Feature Manipulation Services (GFMS), shown in Figure A-7, are a category of services that support creation, quality control methods, analysis, display, and generalization of feature collections of interest to an end user. They include capabilities to:

Figure A-7. USIGS Geospatial Feature Manipulation Services

A.2.8 Imagery Exploitation Services

Imagery Exploitation Services (IES), shown in Figure A-8, are required to support the photogrammetric analysis of remotely sensed and scanned imagery, the generation of reports with respect to the results of the analysis, and other products that ultimately reach policy and decision makers and other consumers of the results of photogrammetric analysis. These services measure the spatial characteristics of objects appearing within images, including geometric measurements from monoscopic and stereoscopic imagery, under a variety of acquisition conditions.

Figure A-8. USIGS Imagery Exploitation Services

A.2.9 Feature Analysis Services

Feature Analysis Services (FAS), shown in Figure A-9, are a category of services that exploit information available in a Feature or Feature Collection to derive application-oriented quantitative results that are not available from the raw data itself. These services include, but are not limited to, the following capabilities:

Figure A-9. USIGS Feature Analysis Services

A.2.10 Image Geometry Model Services

Image Geometry Model Services (IGMS), shown in Figure A-10, are a category of services that support using mathematical models of image geometries. The geometries relate image positions to corresponding real-world (e.g., ground) positions. These services include, but are not limited to, the capability to:

Figure A-10. USIGS Image Geometry Model Services

A.2.11 Geospatial Symbol Management Services

Geospatial Symbol Management Services (GSMS), shown in Figure A-11, are those services required for the management of symbol libraries, such as:

Figure A-11. USIGS Geospatial Symbol Management Services

A.2.12 Image Map Generation Services

Image Map Generation Services (IMGS), shown in Figure A-12, are a collection of services for manipulating and combining images for use as image maps and other uses. These services include, but are not limited to, the capability to:

Figure A-12. USIGS Image Map Generation Services

A.2.13 Image Synthesis Services

Image Synthesis Services (ISS), shown in Figure A-13, is a category of services for creating or transforming images using computer-based spatial models, perspective transformations, and manipulations of image characteristics to improve visibility, sharpen resolution, and/or reduce the effects of cloud cover or haze. These computations include, but are not limited to, the capability to create:

Figure A-13. USIGS Image Synthesis Services

A.2.14 Image Understanding Services

Image Understanding Services (IUS), shown in Figure A-14, are a category of services that provide automated image change detection, registered image differencing, significance-of-difference analysis and display, and area-based and model-based differencing. Capabilities included in this category include, but are not limited to:

Figure A-14. USIGS Image Understanding Services

A.2.15 Geospatial Display Services

Geospatial Display Services (GDS), shown in Figure A-15, is comprised of services that prepare and render one or more Feature Collections or Coverages to an output device. The output device may be a (temporary) electronic display or (permanent) hardcopy printer (e.g., printing a map or chart). The services include, but are not limited to capabilities that:

Figure A-15. USIGS Geospatial Display Services

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