ArcUser Online

Visualizing an Enterprise Approach to Imagery
Managing, analyzing, and serving imagery in ArcGIS 9.3

GIS users need imagery applications that do more than analyze—they also need to manage, process, and serve large volumes of imagery. ArcGIS 9.3 addresses the imagery workflow over server, Web, desktop, and mobile platforms and works with ArcGIS Online services to provide access to extensive, current image data.

Key Developments on the Server

ArcGIS Image Server revolutionizes the way imagery is used in GIS by making just the imagery needed available very quickly. Raw imagery can be processed on the fly.

ArcGIS Server 9.3 transforms imagery workflows and alleviates the storage and data management challenges associated with supplying imagery for GIS applications. It furnishes services that use imagery in modeling, analysis, and data management and can supply a framework for building applications.

GIS end users and those who administer GIS systems have very different expectations of the software used for managing imagery. ArcGIS Server addresses the needs of both groups. Fast performance, access to large amounts of data in a timely fashion, metadata, image quality, and geometric and radiometric accuracy benefit end users. Easy installation, simple workflows, reduced storage space requirements, integration with other systems, stability, and scalability satisfy the requirements of administrators. The ArcGIS Image Server extension to ArcGIS Server plays an important role in fulfilling the needs of both end users and administrators.

Imagery On Demand, On the Fly

ArcGIS Image Server revolutionizes the way imagery is used in GIS. A stand-alone product that was released with ArcGIS 9.2, it is integrated with ArcGIS Server as an extension at 9.3.

Although better-quality imagery in greater quantities has become readily obtainable, until recently the workflow for making that data available to users was relatively unchanged. Traditional methods required preprocessing huge blocks of imagery data to obtain the relatively small portion of the data needed for a task or analysis. Preprocessing could take days, weeks, or months, thus limiting the currency (and value) of data. In addition to latency issues between capture and use, preprocessing entire blocks of imagery data generated additional, and not inconsequential, intermediate files with their own storage and management requirements.

In contrast, ArcGIS Image Server responds to browser requests and handles image processing on the fly for just the specified area of interest, making image data available for use immediately after capture. Raster datasets remain on the server in their original form. Image Server performs radiometric correction, geometric rectification, and image enhancement processes on demand. Multiple products can be generated from a single source dataset. For existing repositories of preprocessed data, ArcGIS Image Server also supplies quick access. Whether raw or processed imagery, this extension transforms the workflow for accessing imagery and increases its value by eliminating processing and distribution bottlenecks.

Services for Imagery

Imagery can be combined with other data using Map, Globe, Mobile, and Image Services. Map Services fuse vector and raster data and serve it as an image. Globe Services fuse imagery with 3D vectors and serve that data as 3D globes.

ArcGIS Server and the ArcGIS Image Server extension acquire, manage, process, and serve imagery data from many sources to clients on the desktop, Web, and mobile devices.

A new and fast service for use in browsers or desktop image processing programs, the Image Service is new in ArcGIS 9.3. It is a lighter-weight service optimized for delivering raw or finished imagery that can be RGB, panchromatic, multispectral, or elevation data stored in a geodatabase or file system. Data sources for Image Services are raster datasets, in formats such as TIFF, MrSID, IMAGINE (IMG), or JPEG2000, or can be raster mosaics. With the Image Server extension, Image Services can also use compiled image service definition (ISCDef) data. Image Services can be managed either with the ArcGIS Server Manager or ArcGIS Desktop ArcCatalog application.

The Image Service also includes a new data source service, the Web Coverage Service (WCS), for publishing raster data that can be manipulated by clients. This is another service used by Esri software, such as Web Map Services (WMS), that supports Open Geospatial Consortium (OGC) specifications. With WCS, clients can obtain subsets of data; request that data be resampled, reprojected, or returned in a specific raster data format; and output files in GeoTIFF, National Imagery Transmission Format (NITF), Hierarchical Data Format (HDF), JPEG, JPEG2000, and PNG formats.

New Sources for Imagery

ArcGIS Online, a whole family of rich content Web services that are highly integrated with ArcGIS, extends and enhances ArcGIS functionality with content, tasks, user services, and developer services. ArcGIS Online gives users access to content from leading imagery providers such as DigitalGlobe, i-cubed, and Meteorlogix. This imagery can be added as reference layers to existing maps or combined with services from ArcGIS Server, ArcIMS, WMS, and KML. With 9.3, ArcGIS Online now supplies developers with tasks that can be incorporated into custom applications.

ArcGIS Data Appliance packages terabyes of prerendered data that includes worldwide imagery as well as street map, shaded relief, and elevation data that is optimized for ArcGIS Server and can be fused with local data.

Access from Many Clients

ArcGIS Server 9.3 supplies a strong foundation for not only managing imagery but also serving it to any kind of client. The Web is the new pattern for implementing GIS. Basemaps for consumer visualization, furnished by Microsoft, Yahoo, and Google, that allow users to combine other data from the Internet with spatial information in mashups are familiar.

The native client for ArcGIS Server, ArcGIS Explorer, is a geobrowser similar to Google Earth that can access many sources of imagery and has additional capabilities. ArcGIS Explorer can call on ArcGIS Server to perform geoprocessing and other tasks and integrate services.

Organizations can also deploy maps and GIS tasks to mobile devices using ArcGIS Mobile with ArcGIS Server. Mobile applications for military, homeland security, public safety, utilities, and other sectors use imagery to orient field-workers and identify features.

In addition to ArcGIS Explorer and ArcGIS Mobile applications, ArcGIS Server supports third-party client applications from Autodesk, Bentley, and others. This lets users leverage imagery in other applications. The ability to serve multiple image file formats from multiple clients eliminates conversion of source data to proprietary formats and reduces both storage and processing costs. By making imagery rapidly available in the formats needed, ArcGIS 9.3 greatly enhances the value of imagery.

Enterprise Mashups with ArcGIS Server

Users can develop ArcGIS Server Web applications using pure JavaScript APIs powered by back-end REST services. These applications typically use imagery data as a reference layer and can mashup ArcGIS services, Google Maps, and Microsoft Virtual Earth. The new JavaScript API exposes most services available in ArcGIS Online for use in mashups.

Working Directly with Rasters on the Desktop

In ArcGIS Desktop 9.3, new imagery tools and functionality in ArcMap give greater control when manipulating imagery. New repair and export catalog path tools save time when working with unmanaged raster catalogs. Operations such as mosaicking can be accomplished more quickly. The color correction tool balances and matches color between mosaic tiles. ArcGIS Desktop now also supports clipping irregular areas of rasters.

Supporting Enterprise Workflows

In response to the greater role of imagery in creating geospatial information, Esri has expanded ArcGIS as a comprehensive system for managing, processing, analyzing, and serving full, rich imagery—not just as a map but as the full stack of multispectral data—that can be fused with other data sources in a workflow that addresses the needs of organizations for better geospatial information.