An overview of the ArcGIS Image Server
Release 9.2 Last modified April 14, 2008	Print all topics in : "About the ArcGIS Image Server"

The ArcGIS Image Server allows you to manage, process, and quickly serve large quantities of raster data for visualization and analysis to a variety of clients. The ArcGIS Image Server can serve all types of raster data for a variety of applications including:

• Raster data covering a specific area, such as digital orthophotography for a county
  
• Raster data of a specific type, such as Landsat 1G satellite imagery
  
• Raster data that has restricted use, such as imagery that is only available to a specific customer
  
• Raster data processed for special thematic uses, such as sea-surface temperature
  
• Raster data requiring preprocessing, such as georeferencing or generating slope from a digital elevation model (DEM)
  

Key features

One of the most important key features of Image Server is on-the-fly server-based image processing. The Image Server resolves bottlenecks in conventional image-processing workflows by enabling the raster datasets to be stored directly as files on servers, then processed and distributed directly without extensive preprocessing or loading of the data into a database. Other key features include

• Fully scalable enterprise client/server architecture
  
• Fast access to extensive imagery
  
• Direct support of multiple file formats and compressions
  
• Multiplatform GIS, CAD, imaging, and Web access
  
• Extensive service and image metadata support
  
• Independence from third-party software or DBMS
  
• Data security and access logging
  

The raster data stored in the Image Server may be a preprocessed product, such as tiled orthoimagery; or semiprocessed data, such as georeferenced but overlapping orthoimagery; or primary data, such as raw scanned frames or satellite images. Utilizing the server's processing power, multiple image products can be generated from a single data source, each with different radiometric, geometric processing, and compression options. This methodology removes data management problems associated with multiple preprocessed datasets and can substantially reduce data storage requirements. Server-side processing also enables access to raster data from thin client applications, reducing requirements for workstations to access and process the data.

On-the-fly processing also allows graded data access that enables high-resolution georeferenced imagery to be distributed and made available to the end users immediately on acquisition. The initial data may not be in the final state but still provides the information required for many applications. As the more detailed parameters for production, such as image enhancements, frame orientation, terrain models, or mosaic lines, become available, these can be added to the service to improve the quality of the product without the need to redeliver the imagery. The quick access to the imagery after acquisition reduces the latency between image capture and usage, thereby maximizing the value of imagery.

Using Image Server, the high value of new raster datasets can be truly exploited for a range of applications including:

• Emergency response and planning for security and military operations that need rapid access to huge raster datasets after acquisition
  
In emergency situations, people need access to information quickly. Image Server allows you to take the acquired image data and quickly get it online for people to see it as georeferenced data. Additionally, you can update the service with new imagery as it becomes available or update the georeferencing or radiometric processing as better parameters are determined.

• Municipalities and utilities, where a large number of users need access to imagery from different applications
  
Municipalities often have many needs for the same imagery—often in different applications. Some municipalities provide their imagery to the public as orthorectified datasets. They may also use them in-house in their planning departments. It is possible the planning department requires a better resolution of the imagery than the public. It would be possible to use the same data but restrict the public to a coarser resolution.

• Data acquisition and provisioning organizations that need to manage, process, and distribute huge quantities of imagery
  
Such organizations may need to keep catalogs of a huge number of images and provide access to subsets of the images as services or quickly create products for distribution. With the Image Server, not only can the large quantities of image data and their attributes be managed easily, but the required products can be defined as dynamic services available for immediate access or processed to a product for conventional distribution.

• Environmental organizations that need to process, manage, and compare many different types of imagery
  
In environmental applications, there are often requirements to handle many different data sources with different dates, spectral characteristics, and resolutions. With Image Server, such imagery can be accessed as multiple services for viewing in a GIS or for image analysis applications.

• Archiving applications, where large quantities of imagery need to be scanned and cataloged, then accessed in both original and georeferenced form.
  
For the archiving of imagery, very large numbers of images are available that are difficult to preprocess into a single product, as many parameters, such as georeferencing will only become available later as the need arises or when more accurate control or georeferencing models become available.

Image Server is not a GIS or an image analysis application but the backbone for georeferenced imagery required by these and many other applications. Scalable and designed to handle thousands of images simultaneously, Image Server can handle huge quantities of images, now and in the future. It solves the problems related to geoimagery by redefining the methods of management, processing, and distribution of such imagery. Thus, Image Server is the comprehensive solution for georeferenced imagery.

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