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.
- Sharing restrictions—will the layer need to be shared with the publicly?
- 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
When you create an imagery layer in ArcGIS Online you are hosting an imagery layer that can be shared with others online. These layers will have the (hosted) label in the layer item name when viewed in the Contents group in ArcGIS Online. Imagery layers without the (hosted) label are referencing other hosted imagery layers in ArcGIS Online. Duplicating and saving imagery layers can create items within your organization that reference the imagery layers. For more information on managing your hosted imagery layers, please see Manage hosted imagery layers.
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.
Imagery format capabilities
| Imagery format | Pixel value access | Raster analysis ready | Modify symbology | Sharing restrictions | Maintains information about input images | Supports multidimensional data |
|---|---|---|---|---|---|---|
Tiled imagery layer |
|
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| No restrictions can be shared with public. |
| |
Dynamic imagery layer |
|
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| Cannot be shared with public as hosted layer. *See Note | When the Image collection capability enabled the input imagery information will be maintained. |
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Tile cache | Pixel values cannot be identified and raster bands combination cannot be altered | Can be used for deep learning inferencing | No restrictions can be shared with public. | |||
Map image | Pixel values cannot be identified and raster bands combination cannot be altered | No restrictions can be shared with public. |
* 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 layers
When imagery layers are created, they are considered to be hosted in ArcGIS Online, which allows you to use the imagery layers online as either a dynamic imagery layer or a tiled imagery layer. Both imagery layers can be used for similar purposes, but there are some differences between the two types.
Dynamic imagery layers
Dynamic imagery layers and dynamic image services are published in ArcGIS Enterprise or published from ArcGIS Pro to an ArcGIS Image Server site. Dynamic imagery layers can also be hosted in ArcGIS Online by users with a Creator, Professional, or Professional Plus user type with the Publish Hosted Dynamic Imagery privilege. 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 the publisher shares the dynamic imagery layer or dynamic image services with you, you can add it to Map Viewer or Map Viewer Classic, where you can query and analyze it.
Note:
Dynamic imagery layers can only be shared within your ArcGIS Online organization and cannot be shared with everyone.
Tiled imagery layers
Tiled imagery layers are published and hosted in ArcGIS Online. These layers are image services generated from one or more image files. If a tiled imagery layer is created using multiple images, the images are mosaicked together into a single image. Source image and raster files are converted to Cloud Raster Format (CRF) when uploaded to your ArcGIS Online organization. You can share, query, and analyze hosted tiled imagery layers in Map Viewer Classic, and access them as static image tiles with client-side processing and rendering.
If WMTS is enabled, the endpoint link will be under the service's REST page. For more information about how to enable WMTS, review the documentation on the requirements to enable it here.
A Creator, Professional, or Professional Plus user type with the Publish tiled imagery layers privilege is required to publish hosted tiled imagery layers to ArcGIS Online.
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.