When we designed WWT it was in the spirit of the MSR TerraServer project, putting lots of stuff on-line for people to use, but on a petabyte scale. Surprisingly though, WWT has a offline mode that allows your run virtually any feature without an internet connection. This is possible because WWT caches all the data it ever downloads and won't delete it until *you* ask. This is for performance reasons. We want to spare our servers, your internet connection and make WWT's reliability not based on the current connection state. Over time a heavy desktop user, a kiosk or a full-dome planetarium might go thru a whole day without having to download a new tile.

The reason caching works is while there might be potentially a petabyte of data your *could* download, your interests are usually narrower than that. Just imagine how often you drive down a street you have never been before. When you are young, that might be often, but as time goes by you just keep going by familiar territory.

So if you have to setup a WWT laptop running off a solar charger in the middle of the Kalahari dessert without access to the internet how do you give a new laptop the experience of your age? That is where the WWT Eclipse cache management tools come in handy. They allow you do save and load an entire cache to a portable USB memory stick or hard drive. The cache tools also allow you to download entire time sets for popular times, or purge un-needed cache entries for others. Using these tools together you can create a cache that can be loaded onto a memory stick, DVD, hard drive so a free-standing computer can run WWT and have a fairly rich experience without ever connecting to the internet.

Explaining this all in text in a blog post would be a bit much, so I produced a video to explain the process.

You will need one of the Eclipse builds of WWT, available right now in the WWT Eclipse page here.

See the attached Word doc for more details.



Click here to play this video