Image Services

An image service is a type of resource that is exposed by the ArcGIS Server REST API. A client can use an image service resource to have dynamic access to raster data, where rasters can be dynamically processed and mosaicked on the fly. An image service supports accessing both the mosaicked image and its catalog, as well as individual rasters in the mosaic. Clients primarily access image service rasters dynamically through the Export Image operation, where a rendering rule and mosaic rule can be specified. A mosaic rule defines how individual images should be mosaicked. It specifies selection, mosaic method, sort order, overlapping pixel resolution, and more. Rendering rules (also known as raster functions) specify how the requested image should be rendered, and examples include 'Hillshade', 'ShadedRelief', and 'Slope'. For more information on rendering rules, please consult the REST Raster Functions documentation.

Since the ArcGIS Server 10.1 release, an image service can also support tiled access to pre-processed raster data. While dynamic access provides much more functionality and flexibility, tiled access provides faster access to pre-rendered pictures. You can see whether an image service has pre-rendered tiles available for a client to consume by navigating to the resource's REST URL, which is of the form http://<catalog-url>/<serviceName>/ImageServer. A resource with tiles available will possess a 'Tile Info' item with information about the tiles, including the levels of detail available and the spatial reference of the tiles.

For more information on image services, including their supported operations and child resources, please review the REST API documentation for ImageServer.