There are many imagery formats to share imagery and raster data available on the web. Each format has been created with certain functionality to meet specific organizational needs. For some organization, sharing the imagery may need to include the pixel values and raster bands for analysis and custom visualizations. For other organizations, it may simply be to provide context for other applications. Within these groups, there is also more customization to limit the manipulation of the input imagery or provide specific visualizations.
Imagery layers, tile caches, and map image layers can be used to share the imagery within your organization, but the characteristics of each format differs. It is important to consider these characteristics when choosing an imagery format based on which one best fits your needs. There are several characteristics of each imagery format that should be considered including:
- Pixel value access— will they want to identify specific pixel values?
- Raster analysis ready—can be used as input for raster analysis tools.
- Modify symbology—raster band combinations can be modified and other visualization properties.
- Maintains information about input images—will the user want to manipulate the image display order? Or use the input images separately?
- Supports multidimensional data—image format maintains access to multidimensional data
All of these imagery layers can be added to a map or web map, but how they function can determine which imagery layer is most appropriate. The characteristics of each type of imagery layer is described below. Consider which type of imagery format is best for you based on those characteristics.
* Hosted dynamic imagery layers cannot be shared with public (Everyone), but image services from ArcGIS Image Server can be shared as items in ArcGIS Online and shared publicly.
Imagery format capabilities
| Imagery format | Pixel value access | Raster analysis ready | Modify symbology | Maintains information about input images | Supports multidimensional data |
|---|---|---|---|---|---|
Dynamic imagery layer |
|
|
| When the Image collection capability enabled the input imagery information will be maintained. |
|
Tile cache | Pixel values cannot be identified and raster bands combination cannot be altered | Can be used for deep learning inferencing | |||
Map image | Pixel values cannot be identified and raster bands combination cannot be altered |
Dynamic imagery layers
Dynamic imagery layers and dynamic image services are published in ArcGIS Enterprise and are typically generated from a mosaic dataset or a collection of images. They are based on a single image or a collection of images that provide dynamic processing capabilities on the data for custom visualization in a map.
When a dynamic image service is referencing image files that are stored on and managed by ArcGIS Enterprise, it is considered a hosted imagery layer and appears in the portal as Imagery Layer (hosted). When a dynamic image service is referencing image files stored in a data store, it is no longer managed by ArcGIS Enterprise and appears in the portal as Imagery Layer. When you publish a dynamic image service from ArcGIS Pro, it is shared as a web imagery layer. Dynamic image services can be shared, queried, and analyzed in Map Viewer Classic, and processing and rendering are performed by the server.
An ArcGIS Image Server license is required to publish a dynamic image service to ArcGIS Enterprise.
Tile caches
Cached layers are organized collections of image tiles for specific geographic extents, projections, and levels of detail that are pregenerated on a server. Cached map layers include cached map services and cached image services and can be generated from a map, a raster or mosaic dataset, or an elevation dataset. Cached layers support fast visualization of prerendered maps, since the images are prerendered as many tiles and the server distributes the prerendered tiles whenever you open the layer. These map layers are created and stored on the server after you upload your data. They are appropriate for basemaps that give your maps geographic context.
Tile caches are sets of tiles (images) generated from a map, a raster or mosaic dataset, or an elevation dataset. These tiles can be displayed quickly in web maps at different scales, and they cannot be used as inputs to analysis tools. When elevation data is used to generate a tile cache, it is considered a web elevation layer.
Tile caches are not reprojected in web maps, so the projection and tiling schema must match that of the basemap, or the tile cache must be used as the basemap.
Map image layers
Map image layers are collections of map cartography organized by location and scale. These layers can include both features and imagery, and they can be displayed dynamically or as cached image tiles.
The source of a map image layer is a map service, so the feature layers contained in the service may be identifiable in a web map. However, if raster data is included in the map image layer, pixel value and band information is not available in the map image layer. You cannot perform raster analysis with a map image layer. Raster or imagery data in a map image layer operates much like a tile cache. As you browse the map, new map images are generated and displayed.
Map image layers can be dynamically displayed over basemaps that use a different coordinate system. For map image layers displayed as cached image tiles, the tiling schema must match that of the map's basemap or the map image layer must be used as the basemap.