Geomagnetic indoor positioning without beacons or hardware - the reality of a flawed system

One of the biggest trends of recent years in indoor localization, as hardware- and beacon-based indoor positioning systems have improved markedly, has been companies seeking the next quantum leap forward - accurate indoor positioning, without the need for beacons or hardware to be installed.

In most cases, these companies claim that their systems operated by exploiting the earth’s geomagnetic field.

In theory, geomagnetism could deliver an accurate indoor positioning solution without the requirement of purchasing, installing, and maintaining infrastructure equipment. Unfortunately practical, real-world results don’t always bear out the theory.

So how have they fared, and has the truth finally caught up with the hype? In this article, we’ll explore:

• The theory behind a geomagnetic indoor positioning system.
• How a geomagnetic system is set up.
• The advantages and disadvantages of a geomagnetic system.
• Real-world results with geomagnetic (the proof of the pudding).
• Our inescapable conclusion.

How geomagnetic positioning works in theory

The earth’s magnetic field is a naturally occurring phenomenon. When it passes through the steel structure of a building and certain electrical equipment, each location in a room will have a unique magnetic field signature. Using these specific features to build a dataset, referred to as the building's “geomagnetic fingerprint” or “fingerprinting map”, implies geomagnetic positioning could be used for indoor positioning and navigation purposes.

The Earth’s magnetic field (the geomagnetic field). Source: ResearchGate	IPS using geomagnetic positioning technique. Source: ExtremeTech

In theory, it should be possible to construct an indoor localization platform based on fingerprinting a building’s geomagnetic field utilizing the built-in magnetic sensor (the compass) as well as other sensing technologies within a smartphone. This approach would negate any physical infrastructure requirement and thus reduce the set-up cost. Individual buildings could be identified by the unique magnetic disturbance their steel infrastructure creates, issues caused by local magnetic variations could be compensated for, and user devices (such as cellphones) could be located.

Fingerprinting itself is not without significant challenges, as we discuss in this post.

That’s the theory, now let’s explore setting up and locating devices, before moving on to the reality behind geomagnetic positioning.

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Setup and locating devices

Setting up a geomagnetic positioning system involves someone surveying the location for geomagnetic signals at multiple points and creating a radio "map" or "dictionary". 

Once set up, when someone visits the location you look at the geomagnetic signals their cellphone is picking up and compare them to the map that was created previously.

You then know that if their device is detecting signals X, Y, and Z and if the radio map picked up the same signals, with the same strength, at point A, then the user must therefore be at that same position.

Utilize magnetic field features to build a fingerprint map. Source: A New Fingerprinting Database for Indoor Localization

This brings us to one of our first drawbacks of a geomagnetic-based system. When people imagine a beacon-based system, they imagine an onerous process of installing hardware throughout a building, whereas a geomagnetic system is often sold as a seamless, unobtrusive setup. In actual fact, the process of fingerprinting a building - particularly one with a complex layout - can take far longer than installing hardware.

The advantage and disadvantages of geolocation

When looking at the advantages and disadvantages of geolocation, it’s important to appreciate that the advantages are purely theoretical. In effect, geolocation doesn’t work as theorized and the main selling point of a system that doesn’t require hardware has always cost.

Advantages

Cost

One advantage of an indoor positioning system that doesn't leverage beacons or other hardware is cost. Though in some cases, such as the BLE beacons favored by Pointr, the cost of beacons is now relatively minimal, not requiring any hardware at all still remains the cheapest option.

No disruption to the building itself

One of the main hinderances encountered when discussing indoor localization systems is that for some businesses, installing hardware in their building is simply a non-starter; their building may be listed, protected, or not be able to altered for another technical reason. For businesses that rent their properties, they may not want to add a layer of complexity to discussions by involving the building's owner. 

Disadvantages

Inaccuracy

Geomagnetic systems have the deceptive quality of providing accuracy when first set up, when the fingerprinting map is fresh, but their usability quickly deteriorates, which negates and overwhelms any initial "cost-benefit". Over time, a large number of factors can impact the accuracy of the previously-taken fingerprinting survey, including any building layout changes or even just the amount of conflicting sensors or signals present in the building. 

This is because indoor geomagnetic positioning relies on "geomagnetic fingerprint" datasets recorded at multiple points and stored in an IPS database to measure the indoor magnetic field. In addition, geomagnetic IPS technology utilizes the built-in magnetic sensor (compass) in smart mobile devices, which is notoriously inaccurate (see Fig. 1), compounding the issue with geomagnetic and precise blue dot orientation.

Fig. 1: Compared to Pointr’s Deep Location®, solutions that rely upon a smartphone’s built-in “compass” show relatively inconsistent orientation.

Cost

As previously stated, one of the big perceived advantages for no-hardware geomagnetic systems is that they must be cheaper, because they don't require anything to be installed. However, in many geomagnetic systems, this is a false economy. The initial setup and launch of the system may indeed prove less expensive than the setup of a geomagnetic system, but the cost of repeated surveys to re-fingerprint the location, or even the cost of installing hardware after the geomagnetic system fails to deliver, can quickly add up.

Scalability

Geomagnetic is not scalable; every part of a building needs to be manually mapped, meaning the bigger the building, the bigger headache you’re creating for yourself in the long run. Geomagnetic requires constant maintenance as it needs an onsite survey and re-recording every time there's a venue change.

Functionality

Geolocation doesn’t run in the background on iOS which means you can’t serve contextual notifications on iPhone, and you can’t collect customer flow data while the user’s cell phone is in their pocket. BLE, on the other hand, supports both.

Unreliability

The local magnetic field, and therefore the accuracy, is affected by moving metal objects like lifts or metal cabinets. Even with regular (and costly) re-configuration, it’s impossible to mitigate for factors like this.

Use cases of geomagnetic indoor positioning - and what went wrong

At Pointr, we have practical experience of geomagnetic positioning systems not living up to their billing.

Several companies had been advertising that you don’t need any hardware to achieve accurate positioning with geomagnetic, ultimately their disappointed customers reached out to Pointr to address their issues. Here are a few examples.

• A shopping mall group in Hong Kong asked us to fix their accuracy after they were told “you don't need hardware" with geomagnetic positioning. When they found the lack of accuracy unusable, they were told that beacons could be installed to improve it - completely defeating the purpose of a “non-hardware” system. After 5-6 years, the company that installed the system is now honest about it and mentions this on their website. An Indian Airport came to us after a similar experience.
• Another mall operator in Canada considered Pointr for their indoor positioning needs but went with a competitor recommending a geomagnetic solution for only 20% of our price. Three months later they came back to us to ask if we could fix it. Again, the option to install BLE beacons was also offered by their supplier to improve accuracy.
• A famous New York department store had a bad experience with geomagnetic and ultimately chose Pointr for our accuracy, functionality, and scalability.

We have many more cases like this that back up the issues associated with geomagnetic highlighted in this article.

Indoor positioning and navigation without beacons - is it worth it?

Even with the above disadvantages and geomagnetic use cases discussed, some may still feel that the promise of a system that does away with the hardware is worth the potential trade-offs. However, it's worth dispelling some of the myths surrounding beacon-based systems.

• "Beacon-based systems must cost more than systems that don't need them" - While it is true that the initial setup of a hardware-based system may well cost more than a geomagnetic system that requires just a fingerprinting survey, the costs associated with this latter type of system can very quickly escalate due to the need for repeated fingerprinting surveys or even installing hardware after all to ensure a useable experience. Furthermore, the cost of effective BLE beacons with long-lasting battery life favored by Pointr have dropped markedly over the years.
• "Installing extensive hardware will create disruption and damage our building" - In fact, the idea of a beacon-based system needing 'hardware install' is a somewhat misleading one. The modern BLE beacons favored by Pointr are magnetic, meaning that in many cases, they can be attached to metal fixtures and removed simply by sliding them off, leaving no trace. In other cases, beacons can be attached via a plate which is magnetic on one side and has an adhesive on the other, which again can be removed with minimal fuss and trace. Beacons are also smaller than palm size and can go virtually unnoticed unless looked for.
• "Putting up beacons will take much longer than fingerprinting a building" - In conjunction with our previous two answers, this is rarely the case. Beacon installation is an art that Pointr's team has mastered, which has enabled us to launch deployments with extremely quick turnarounds, such as events and conferences where we only have access to the site for a matter of hours before the system needs to be live. Not only that, but as previously mentioned, beacon battery life can last for several years, whereas fingerprinting needs to be repeated every few months (based on our discussions with former users of geomagnetic systems) in order to maintain some degree of accuracy.

It's for these reasons that we like to say that while geomagnetic systems can claim to be hardware-free, a beacon-based system like Pointr's is maintenance-free; once setup, the system will continue to work as well as it did on the first day of operation.

• Many reasons people don't want hardware 
• However beacons now inexpensive and simple to install
• Don't cost much
• Can be installed quickly

Finally, geomagnetic systems are hardware free, but beacon based systems like Pointr's are maintenance free

Conclusion

While on the face of it a geomagnetic system may seem an attractive solution to indoor positioning, mainly because of its low cost and lack of hardware requirements, that’s not the whole story. The accuracy of systems that have been attempted has been proven to deteriorate over time with many clients realizing, only after the fact, that the solution they’ve been sold was not fit for purpose.

It’s also troublesome that the future of support for geomagnetic systems is in doubt. This uncertainty strongly suggests that a geomagnetic solution for indoor positioning is just not worth the gamble.

Next moves

It’s clear that an indoor positioning solution that doesn’t rely on geomagnetic is preferable to one that has an unreliable and unscalable technology at its core.

Pointr’s Deep Location® is such a solution. We don’t use smartphone compasses or fingerprinting and we’re scalable to thousands of venues at speed, something that definitely can’t be said of geomagnetic.

Pointr’s Deep Location® technology is live in 27 countries and over 3000 venues.

Talk to us today and start your indoor positioning journey with Pointr.

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Related topics:

• An Evolution of Wayfinding Technology with Pointr
• Location fingerprinting - what is it, and should you choose it as your IPS technology?
• Can Google Maps work indoors, and what are the alternatives?
• How to Select the Right Infrastructure for Indoor Positioning?

Author:

	Les Blythe
	Eva Cheng