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Indoor Map using Magnetic Fields

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Location Based Services are increasingly being used to present contextual information to the user. With Google Maps charting the entire globe, it is trivial to add geo capabilities to your application. In today’s world, many apps & services use maps as the primary interface to interact with users. Services like taxi booking or house rental have seen significant increase in application usage, when using maps as their primary interface.

The primary technology used in accurately locating a device is GPS (Global Positioning System). However this technology only works well when outdoors, limiting the usage to outdoor map based services. There is immense scope to build innovative apps & services, if a user location can be tracked to an accuracy of a couple of metres within a mall or a building. This has led to technology companies trying to find a feasible solution for Indoor Mapping.

Various technologies like Bluetooth, Wi-Fi, Inertial Measurements have been applied to find a solution. iBeacon from Apple, Cisco Wireless Location Appliance are products attempting to dominate this space. Another very interesting technology that is being applied to solve this last frontier of digital cartography is Geo-Magnetism.

Magnetic Field Models are used for navigation by various government agencies and can be measured by a sensor on or above the surface of Earth. Of the various sources that generate magnetic fields, it is the Earth’s main magnetic field that accounts for 95% of the field strength at the Earth’s surface. The World Magnetic Model maintains such a Magnetic Field Map and updates it every 5 years (last released in 2015). The magnetic field components X (northward), Y (eastward), Z (downward), F (field strength), D (declination), I (inclination), and H (horizontal strength) are measured in geodetic co-ordinates.

Magnetic positioning can offer pedestrians with smart phones an indoor accuracy of 1–2 meters with 90% confidence level, without using the additional wireless infrastructure for positioning. Magnetic positioning is based on the iron inside buildings that create local variations in the Earth’s magnetic field. Un-optimized compass chips inside smart phones can sense and record these magnetic variations to map indoor locations. This technology is independent from external infrastructures such as radio access points and can provide scalability without large infrastructure investments.

The Android OS through Geomagnetic Field provides support to retrieve the magnetic field co-ordinates from hardware components. Similar support is provided by the Magnetometer in iOS. App developers can leverage this technology to provide fairly accurate Indoor Mapping, opening up a world of new business opportunities. Indoor Mapping can be applied to various use cases like Location-Based Mobile Marketing & Indoor Navigation in Shopping Malls, Airport, Academic Buildings, Train Stations, Stadiums, Parking Spaces, Hospitals, Cruise Ships or Business Parks.

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