How to create and host an imagery cache on ArcGIS Online
If you don’t have a way of hosting services or cache on your own server (possibly because of your organization’s IT restrictions or policies), you can still provide the public access to features and cache by hosting these on ArcGIS Online. You'll need to have access to your own ArcGIS for Server in order to prepare map or imagery cache, but you won’t need Server to share it with others. This blog post focuses on preparing imagery cache for hosting on ArcGIS Online.
If you don’t have a way of hosting services or cache on your own server (possibly because of your organization’s IT restrictions or policies), you can still provide the public access to features and cache by hosting these on ArcGIS Online. You'll need to have access to your own ArcGIS for Server in order to prepare map or imagery cache, but you won’t need Server to share it with others. This blog post focuses on preparing imagery cache for hosting on ArcGIS Online.
Before you proceed with hosting your imagery on ArcGIS Online, you should get an estimate of the cost of doing so. Find out the approximate file size of your cache and use this convenient credit calculator to determine the cost.
Assuming that your imagery has already been processed and enhanced to your liking, here are the steps you should follow.
Step 1: Publish imagery service & generate cache
When creating a tile package from an imagery cache with the intentions of hosting it on ArcGIS Online, ensure that the imagery is in the WGS84 Web Mercator (Auxiliary Sphere) coordinate system and be sure to use the following caching settings when publishing it as an image service:
- Set ArcGIS Online / Bing Maps / Google Maps as the Tiling Scheme (scale range)
- Use ‘MIXED’ as the Tile Format
- Set the Compression value to 75 (or greater depending on the desired quality of imagery)
Cache settings
By using the ‘MIXED’ tile format and staying with a compression value of 75, you not only reduce the size of the tile package (and the number of credits required/consumed), but you also remove the ‘white border’ that you'd normally get when caching using a JPEG tile format. This is because JPEG format doesn't support transparency. The illustration below highlights the importance of using the ‘MIXED’ tile format when preparing your imagery cache to be hosted on ArcGIS Online.
Image cache with JPEG tile format
Image cache with MIXED tile format
Step 2: Export tile cache to a tile package
Use the ‘Export Tile Cache’ tool (Data Management) to export tiles from the existing cache to a new tile package so that the imagery can be easily shared and used as a basemap layer on ArcGIS Online. Alternatively, you can right-click the imagery cache and select the ‘Create Tile Package’ option. Save the tile package in a folder on your local computer. ArcGIS Online supports .tpk (tile package) compressed files, but you must have an organizational account to publish them because they consume credits. If your organization has an Enterprise License Agreement, then it'll also have an organizational account.
Export Tile Cache settings
Step 3: Review & upload tile package
Tile packages cannot be previewed in ArcCatalog, but rather must be unpacked in ArcMap to review their contents. Simply add the new tile package to the table of contents in ArcMap and display it over an ArcGIS default basemap to ensure that no ‘white borders’ or ‘white pixels’ show up around or within the imagery. Using the ‘Share Package’ tool (Data Management), sign into your ArcGIS Online Organization account and upload your tile package to your account. You have the option to choose whether to share the uploaded tile package with everyone or select a specific group(s).
Share Package settings
Step 4: Publish imagery on ArcGIS Online
In your Web browser, log into your ArcGIS Online Organization account and go to the ‘MY CONTENT’ tab. You'll see that your tile package has been uploaded to your account.
Seeing your content in your ArcGIS Online account
Click on the tile package and then click ‘PUBLISH’ to unpack the tiles and host them as a service.
Once successfully published, you'll notice that the tiles are hosted on your account. You can click on the tiles service in the ‘MY CONTENT’ tab to view your imagery in an ArcGIS Online Web map. After verifying that the service is running, consider deleting the original tile package so that you don’t have to pay credits to store it.
Tile package displayed on your account
(With contributions from Paul Lefaive, GIS Analyst)