WHAT
The offline maps pattern uses offline maps that can be downloaded to a user’s device to provide access to data when the need arises. They are useful when the user needs access to data in areas in which the internet is slow, mobile data is expensive, or the user cannot get online.
WHY
Offline maps, sometimes also referred to as offline areas, is most useful on mobile devices that are being carried to an area with data-serving limitations, such as slow, limited, or expensive internet connections. In anticipation of these limitations, users may want to download map content to a mobile device while still on a fast and reliable internet connection. This saves time and money and ensures that the content is available before traveling to the underserved area.
WHEN
Offline maps are important for mobile apps that include navigation and route directions, especially when traveling to rural areas with limited connectivity or poor reception. Hiking apps, for instance, must show reliable information about trails while the person is moving along unknown territory. Before the hiker travels into the outdoors, they can download trails and other infrequently changing data so it’s readily available on arrival. Limitations to that approach are that live data feeds such as traffic information, transit updates, or alternative route suggestions will not be available without connectivity.
HOW
Provide a mechanism that allows users to download the map data for a specific region before encountering access limitations. The workflow typically includes the following steps:
- Search for a place or navigate to an area of interest.
- Start the workflow by clicking a button to Save Map Area.
- Confirm the map area to be downloaded.
- Specify the name of the data package.
- Make sure the data package appears in the list of downloaded areas.
- Allow users to update outdated or delete existing downloads.
Once an area is downloaded and the device identifies a slow or no internet connection, the app will use the local version instead of streaming live data. This so-called offline mode may also be triggered because the user has switched their phone to airplane mode. During offline mode, the app should add a message bar informing the user that data is temporarily or permanently unavailable.
The main considerations for the offline map experience are storage space and download size. Inform users of the anticipated package size before they start downloading it. If the size is too large, offer one of the following alternative ways to reduce its volume:
- Select a smaller area. For instance, include only Manhattan instead of the whole city of New York. Alternatively, consider offering predetermined and optimized map packages available for download in this area.
- Adjust the data granularity. Include only important data and omit unnecessary layers. The downside is that relevant information may be missing. Although it’s okay to ask the user to confirm which data layers to include, a better approach is to let an algorithm decide instead of exposing the whole list.
EXAMPLE
The GreenbeltGo app, developed by Greenbelt, Essex County’s Land Trust, is a native mobile app that allows hikers to explore and navigate publicly accessible conservation lands in Essex County, Massachusetts. Knowing that cell phone range varies greatly in rural areas, the app offers users the ability to download offline maps for use on scene. A dedicated Offline Maps page lists the downloaded areas and allows users to start the process of saving a new map area. As part of this process, the user modifies the area to be saved by panning and zooming the map before clicking the Save Area button to confirm the selection. After the offline map is named, the map is downloaded and made available in the offline maps list.
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