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:

• Have the same, or very similar, object signatures
• Operate on the same, or very similar, metadata
• Manipulate or use the same feature type (point, line, polyline, image, etc.)

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:

• Geospatial Information Access Services
• Geospatial Dissemination Services
• Geospatial Information Packaging Services

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:

• Geospatial Information Storage and Retrieval Services
• Geospatial Information Catalog Services
• Geospatial Product Information Services

A.2.1.1.1 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:

• Retrieval of selected MCG&I information, including the capability to request dissemination to client and third-party clients (Thus, this operation supports a form of push-mode transfer through a third-party request.). The retrieval process must support retrieval of features (including images and gridded information) that are contained within a boundary defined by a rectangle or ellipse. Thus, retrieval of portions of one or more images must be supported.
• Storage of MCG&I information in a library
• Monitoring the status of submitted requests, for both storage and retrieval, and for canceling incomplete requests when desired.
• Conversion of retrieved data from the structure or format it in which it is stored in the library to a different structure or format that has been requested by a client, as in converting raster to vector, Vector Product Format (VPF) to Spatial Data Transfer Standard (SDTS), etc.

A.2.1.1.2 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:

• Ordinary catalog search queries by accepting Boolean query syntax expressions as input and returning a set of query hits matching the expression.
• Polygonal query capability enabling ordinary catalog search queries by supplementing Boolean queries with the specification of a polygonal shape. MCG&I information that overlaps any portion of the polygon should satisfy the query if the product properties also satisfy the Boolean query expression.
• Elliptical query capability enabling Boolean catalog search queries combined with the specification of an elliptical shape. The ellipse should be defined by its center point, major and minor axes, and the azimuth rotation from North of the major axis and returns geospatial information that provides coverage of any portion of the ellipse while satisfying the Boolean Query Syntax expression.
• Point query capability to supplement Boolean queries by specifying a geographic point. Image products returned by this query should combine the Boolean Query Syntax expression and coverage of the specified point.
• Get More Results capability to access invocations of the Geospatial Information Catalog Services operations that are unable to return entire sets of query hits in the allocated area for query results. A QueryId value is returned and used with the "get_more_results" operation to obtain the remaining query hits.
• Capability to inform the catalog server that the client does not intend to retrieve additional results from the list provided by the catalog, allowing the catalog server to free any resources allocated for the client's query results.
• Ability to add and remove catalog entries.

A.2.1.1.3 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:

• Feature Compression Service
• Image Compression Service
• Geospatial Information Transfer Service

A.2.1.3.1 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.2.1.3.2 Image Compression Service

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

A.2.1.3.3 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.

• "Geospatial information" refers to MCG&I objects, metadata, and annotations, and may include, but is not limited to: imagery, vector, text, video, signals, and any other appropriate form of data.
• "Geospatial information" may also include object behaviors such as methods written in a scripting or programming language that express functional capabilities of MCG&I objects.
• The term "fundamental units and collections" of MCG&I information refers to both simple and compound objects.

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:

• Select to display or extract only those features that match certain criteria
• Suppress the display or extraction of features that match certain criteria

• Aggregate clusters of point features and create a smooth enclosed polygonal perimeter outline
• Replace the current representation of a feature with a more detailed representation
• Reduce the sinuosity of line features or the perimeter of area features to avoid cluttering in a display window
• Reduce the number of features selected or displayed in a region to present a more pleasing representation of the region, based on a set of properties and/or criteria that are used as a prioritized filter
• Adjust the connectivity relationships of line segments in line, area, or volume features
• Classify features by assigning values to feature properties
• Replace any feature type with another feature type to adjust for changes in resolution of the Feature Collection (for example, replace an area feature with a point or line feature, or a volume feature with a point, line, or area feature, or the inverse of any of these.)
• Remove excessive variations in ridge/course line values to present a more pleasing representation of the ridge/course line skeleton
• Remove excessive variations in surface property values to present a more pleasing representation of the surface

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:

• ingest existing feature collections
• digitize and/or convert softcopy maps and charts to produce a feature collection
• create the geometry and associated feature collection from a subset of another feature collection (e.g., extracting portions of map files to a specified area of interest (AOI), creating a coverage subset of feature information from Feature Collections from databases, capturing textual (Line, Area) properties and metadata, etc.)
• create a duplicate copy of an existing feature, set of features, or Feature Collection for the purpose of modifying that data or including it in a different set of data

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:

• adjust the features in a Feature Collection using one datum and register them to another Feature Collection using a different datum
• transform geographic coordinate values from one coordinate system to another
• perform a point location search from user-entered coordinates according to user-specified coordinate types (i.e., UTM, geographic coordinates and image coordinates)
• apply standard, custom, or computer-generated grids over all imagery types

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:

• Superimposition of annotations on an image allowing for the exhibition of the annotation overlay, the image itself, or both
• Selection of icons and other symbols from a standardized catalog for placement on an overlay
• Retention of an annotation elements' position relative to the underlying image regardless of the action or manipulation performed on the image
• Registration of annotations to user-specified points on the display of the image.

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:

• Provide image enhancements that increase the analyst's ability to distinguish between similar appearing areas of a scene
• Perform geometric operations that change the digital image geometry in a controlled way, so that objects in the resultant image are displaced from their original positions (Note: These are basic image geometry service(s) used by applications and other services, defined elsewhere in this section)
• Manage the manipulation and display of images including the ability to pan, zoom, rotate, and display image histogram characteristics, local pixel properties, and display lookup tables

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:

• Register one feature to another, an image, or another data set or coordinate set; correcting for relative translation shifts, rotational differences, scale differences, and perspective differences
• Examine the internal correctness and consistency of features and their properties as represented in a Feature Collection. This includes the ability to:
  • Adjust the locations of features that have portions of a whole feature separately represented in adjacent Feature Collections to ensure that the feature portions are properly aligned
  • Verify that all features in the Feature Collection are topologically consistent according to the topology rules of the Feature Collection, and identifies and/or corrects any inconsistencies that are discovered
  • Verify that all pixels or grid post values in a Coverage or Feature Collection are reasonable, identifies and/or corrects any inconsistencies that are discovered

Figure A-7. USIGS Geospatial Feature Manipulation Services

• Deconflict features by applying mediative measures to resolve conflicts in data integrity or representation between or among different Feature Collections that contain similar information for a given area
• Modify values of a feature
• Modify the values of metadata elements describing a feature

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:

• Buffering to create a proximity zone of a specified width around the geometry of a feature or set of features in a Feature Collection or Coverage
• Boolean operations to perform binary operations on two or more features or feature collections including, but not limited to:
  • Union operations to compare features from two or more Feature Collections and return non-redundant features that are found in either Feature Collection.
  • Intersection operations to compare features from two or more Feature Collections and return those features that those Feature Collections have in common.
  • Fusion operations to merge two or more features or Feature Collections into an aggregate feature or Feature Collection composed of the formerly distinctly separate parts.
  • Operations to compare two Feature Collections and return the differences between them.
• Capability to determine if any features in the Feature Collection obstruct the path of a designated vehicle based on the properties of the features and those of the vehicle.

Figure A-9. USIGS Feature Analysis Services

• Capability to compute non-stored geometric properties, including relative and absolute error, of a feature from the geometry including, but not limited to, capabilities to:
  • Determine the size of an area feature.
  • Determine the length of a line feature or a straight line connecting two different points of a feature.
  • Determine the angular orientation of a feature, or a line connecting two different points or features, as measured from a standard vector (usually True North).
  • Determine the angular variation of a feature, or a line connecting two different points or features, as measured from a horizontal plane.
  • Transform feature geometry and/or attribute data values from one measurement system to their equivalent value representation in another measurement system.
• Computation services for exploiting elevation coverages and certain other coverages including, but not limited to, capabilities to:
  • Estimate the elevation of a specified point based on its position relative to a set of known elevation values.
  • Determine the average elevation of a Feature Collection based on grid post elevations as input.
  • Identify the highest and lowest property values of a surface in a Feature Collection.
  • Create a terrain profile object derived from an elevation-based Feature Collection.
  • Create a set of lines of equivalent values based on the information available in the Feature Collection.
  • Determine the angle of ground slope from the horizontal at specified points.
  • Determine those ground areas visible and those areas that are hidden as viewed from a specified point.
  • Calculate whether a specified feature is visible from a specified observation point.
  • Convert surface representations between any pair of Grid/TIN/Contour elevation coverage types.
• Capability to create a geospatial model of one or more related Feature Collections using visual cues to give the impression of depth as viewed from a specified angle.
• Capability to interpret feature properties.
• Computation services for exploiting transportation routes recorded as a Feature Collection, such as determination of:
  • The optimal path between two specified points based on the desired input parameters and properties contained in the Feature Collection.
  • Additional paths, other than the optimal path, between two specified points based on the desired input parameters and properties contained in the Feature Collection.
  • The measured distance between two points along a specified path based on the properties supported in the Feature Collection.
  • The length of time it takes to follow a route through the geospatial data in the Feature Collection.
• Services for computing threats using geospatial data recorded as a feature collection, such as:
  • Synthesis of the results of all previously calculated threat fans to arrive at a composite area that is vulnerable to attack.
  • Determination of whether a specified feature is detectable from a specified observation point.
  • Determination of the perimeter of an area feature that is subject to attack based on the properties of a weapon at a known geographic position.
  • Specification of the threat parameters to be used to filter the information in the Feature Collection when performing a threat analysis.

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:

• Use image geometry mathematical models to support image exploitation and manipulation (including supporting various other services that handle images), such as:
  • Computation of a list of image positions corresponding to a specified list of ground positions.
  • Computation of a list of ground positions corresponding to a specified list of image positions. The ground heights are either input as specific values, input as an elevation model, or computed using positions in two or more stereoscopic images.
  • Computation of estimated total ground position error of one point, including the effects of image support data errors, image position measurement errors, height uncertainty, and computation errors.
  • Computation of estimated total ground position error between two points, including the effects of image support data errors, image position measurement errors, height uncertainty, and computation errors.
  • Computation of estimated total image position error, at one ground position, including the effects of image support data errors, ground position errors, and computation errors.
  • Retrieval of the list of current values of image geometry model parameters.
  • Change of current values of specified image geometry model parameters.
  • Change of current values of image transformation parameters (from named value list format). This image transformation relates one version of an image to the original image. A version may be a reduced resolution data set, a simply warped image, and/or a part of the original image.
  • Retrieval of definitions of image parameters, including all information needed to allow display of parameter values and interactive modification of changeable values.

Figure A-10. USIGS Image Geometry Model Services

• Convert image geometry mathematical models into different, but equivalent, geometry models. These geometry models include image geometry parameter values in various specific, image-support, data formats. Operations on geometry models include, but are not limited to, the capability to:
  • Fit a new image geometry model to an existing image geometry model, including computing the estimated errors in the new image geometry model.
  • Receive and check image support data in a specific known format, for one or more images.
  • Retrieve and check the image support data for a specified image, and use this data to create an Image Geometry Use object.
  • Retrieve and check image support data for two or more stereoscopic images, and use this data to create multiple Image Geometry Use objects.
  • Convert image support data from an Image Geometry Use object to external format, including check and store converted data.
  • Convert image support data from two or more Image Geometry Use objects to external format, including check and store converted data.
  • Produce image support data in specified external format from previously entered data, for one or more images. Also, check the image support data and return a list of any "errors" or missing data detected.
  • Change current values of conversion service option parameters (in named value list format).
  • Retrieve current values of conversion service option parameters (in named value list format).
• Adjust one or more image geometry mathematical models to better match other images and/or known ground positions. Adjust geometry models based on corresponding ground and image positions and/or corresponding positions in multiple images, with the estimated errors in these positions and in the original image geometry parameters. Adjustments include, but are not limited to, the capability to:
  • Adjust the values of selected adjustable image geometry parameters for the current set of images, using position data for the current set of points.
  • Add an additional image to the current set of images to be adjusted.
  • Remove a specified image from the current set of images to be adjusted.
  • Add an additional point to the current set of points to be used in image adjustment.
  • Remove a specified point from the current set of points to be used in image adjustment.
  • Change data for a specified point in the current set of points to be used in image adjustment.
  • Change current values of image geometry adjustment service option parameters (in named value list format).
  • Retrieve current values of image geometry adjustment service option parameters (in named value list format).
  • Retrieve data for first point in current set of points to be used in image adjustment.
  • Retrieve data for next point in current set of points to be used in image adjustment, after last point retrieved by Get Next Point or by Get First Point.
  • Retrieve data for a selected point in set of points to be used in image adjustment.
  • Retrieve summary data for first image in current set of images to be adjusted.
  • Retrieve summary data for next image in current set of images to be adjusted, after last image retrieved by Get Next Image or by Get First Image.
• Support adjustment of image geometry parameters, such as:
  • Retrieve names of all parameters of the image geometry model that could be adjusted.
  • Retrieve names of parameters of the image geometry model that are recommended to be adjusted.
  • Retrieve covariance matrix of the current expected errors in and among a specified list of image geometry model parameters.
  • Compute partial derivatives of the image coordinates relative to specified list of adjustable image geometry model parameters, evaluated at a specified ground position.
  • Compute partial derivatives of the image coordinates relative to the three ground coordinates, at a specified ground position.
  • Change values of specified list of parameters of the image geometry model, by the specified value changes.
  • Change covariance matrix of the expected errors in and among a specified list of image geometry model parameters.
  • Compute list of image positions corresponding to specified list of ground positions.
  • Compute list of ground positions corresponding to specified list of image positions. The ground heights are either input as specific values, input as an elevation model, or computed using positions in two or more stereoscopic images.
• Convert estimated errors between covariance matrix form and Circular Error (CE) plus Linear Error (LE) forms. These conversions include, but are not limited to:
  • Conversion of a 3-D covariance matrix to horizontal CE and vertical LE estimates.
  • Conversion of a 2-D covariance matrix to horizontal CE estimate.
  • Conversion of a 2-D covariance matrix to image CE estimate.
  • Conversion of a horizontal CE and vertical LE estimates to 3-D covariance matrix.
  • Conversion of a horizontal CE estimate to 2-D covariance matrix.
  • Conversion of an image CE estimate to 2-D covariance matrix.
  • Changes of current values of accuracy conversion service option parameters. These options include the confidence probability used for CE and LE.
  • Retrieval of current values of accuracy conversion service option parameters.

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:

• Management of symbol libraries, the linking of symbol types to specific features for display, and the representation of symbols as proxies for features in legends and portions of Feature Collections displayed on a screen or printed hardcopy.
• Creation of a taxonomy of symbols from a set of graphic objects to populate one or more symbol libraries.

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:

• Merge multiple images with abutting and/or overlapping spatial coverages to form a single composite with greater spatial coverage.
• Match and blend the radiometric values of corresponding or adjacent pixels from abutting and/or overlapping spatial coverages to form a smooth visual transition.
• Combine information from more than one image into a single image product (e.g., combining one image from SPOT 10m. resolution panchromatic coverage with one of LANDSAT 30m. resolution multi-spectral coverage).
• Adjust transparency of images so when two images are overlaid one upon the other, adjustment is made to common pixel values to allow lower-layered images to be observed through higher-layered images. This capability is typically used to combine images from different sensors with different imaging characteristics, such as combining a panchromatic image and a thematic mapper image into a single color image that allows thematic classifications to be viewed "through" the panchromatic image.
• Transformation of the geometry of images to remove the effect of obliquity and/or rotation in the image acquisition (known as rectification). This capability includes epipolar rectification for stereoscopic viewing.

Figure A-12. USIGS Image Map Generation Services

• Transformation of the geometry of images to remove the effect of obliquity in image acquisition and also remove lateral displacement due to terrain relief (known as orthorectification).

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:

• CAD or other models of elements and objects within an imaged scene.
• A new image from an existing image to simulate changes in acquisition conditions such as illumination, atmospheric effects, or sensor geometry.
• An image as though taken from a location other than that of the original image. Generally, this uses a three-dimensional scene model.
• A series of images with perspective centers changing with observation time as though taken from an aircraft (for example) flying over the scene.

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:

• Comparison of multiple images taken at different times, highlighting areas where significant change has occurred; e.g., the absence of an aircraft where one previously was parked.
• Pattern recognition on an image. Pattern recognition is a capability that detects the existence of a pre-defined or learned pattern, such as edges joined in right angles.
• Identification and classification of objects in an image. Object recognition is based on fully automated or computer-assisted recognition of patterns, from which detection of a known class of object can be inferred (based on prior classification).

Figure A-14. USIGS Image Understanding Services

• Extract of features from an image based on object recognition. Feature extraction implies the detection and identification of an object but further includes the abstraction (or symbolization) of the feature. For instance, detecting, extracting, and abstracting a feature such as a road into a spatial data base or map.
• Display, extraction, and analysis of terrain data. Examples of terrain data of interest are: elevation data, soil types, vegetation classes, and drainage patterns. An example of terrain analysis is the use of digital elevation data with images to generate obscuration profiles, showing visual or signal obscuration between selected points.
• Automatic and interactive negation (determination of origin) of changes detected in objects and relations (e.g., performs site analysis using knowledge-based analytical methods.
• Automatic and interactive detection and counting of objects and relations required for an exploitation task (e.g., perform automatic target recognition).
• Automatic and interactive trend analysis for objects and relations of interest in an exploitation task (to include spatial inference from evidence of as-yet unseen, occluded, or otherwise obscured objects, as well as model analysis using time-series and machine learning techniques).
• Automatic and interactive analysis of sensor line-of-sight, terrain and cultural feature classifications (including standard map features and point target types), vehicle- and unit-level location probabilities, mobility analysis, etc.

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:

• Manipulate one or more Feature Collections or Coverages to display over a base Feature Collection that is already displayed (this includes such applications as distributed collaborative computing).
• Create associations, either temporary or permanent, between or among features in a Feature Collection, symbols in an overlay, etc., for the purpose of their display manipulation as a related unit.
• Introduce detail into a feature to augment or emphasize a particular characteristic.
• Interactively select and highlight a feature or features displayed on the display device.

Figure A-15. USIGS Geospatial Display Services

• Link symbol types from symbol libraries to specific features in a Feature Collection for representation on the output device.
• Render a Feature Collection that has been encoded with symbolized information, to an output device or media.
• Place textual information during the rendering process to provide a more complete description of a feature or set of features.
• Associate ancillary information for a feature or feature collection for display with the feature or feature collection on the output device.
• Manage the output of hardcopy facsimiles of the Feature Collection via a device such as a printer or plotter.
• Display a map inset containing a smaller-scale map to which the geographic position of the displayed map or area of interest is referenced.
• Convert the features in the Feature Collection from one projection system to another to enable their accurate rendering to an output device.
• Control how the Feature Collection is manipulated in a display screen window.
• Specify the Feature Collection, or portion of the Feature Collection (the subset usually resulting from the application of an Area Of Interest as a filter), to be displayed as a map background.
• Specify the scale at which to display the Feature Collection on the output device.
• Instruct the display to lighten the illumination intensity of the feature or Feature Collection in the screen display window.
• Specify in which direction the feature or Feature Collection is to be moved in the screen display window.
• Reposition the Feature Collection in the screen display window in relation to a specified center point that is different from the center point used in the current display of the Feature Collection.
• Specify an angular measure by which the feature or Feature Collection are to be turned about a specified center point.
• Specify a zoom factor for redisplay of the feature or Feature Collection on the screen.
• Stack features, Feature Collections, or Coverages in a specified order for output to a display device.
• Adjust the position of a feature to avoid overlap with other features that would cause cluttering in the display window.