Ask anyone on the street how to get somewhere and they will usually launch Google Maps on the phone in their hand or immediately available in their pocket. However, the scenario is very different when we are lost indoors. Finding our way around complex indoor spaces like railway stations, airports, shopping centres, and hospitals has been a largely analogue experience due to the lack of indoor wayfinding apps. Fortunately, this is changing as a host of companies are starting to develop for indoor spaces.

At Calvium we’ve been designing and developing apps that support people navigating their way around outdoor environments for years. More recently though we’ve been working more and more on developing apps and infrastructure to navigate around indoor spaces. In this article, I want to discuss the challenges this type of wayfinding presents and some of the innovative solutions being presented.

Challenges of Indoor Wayfinding

Wayfinding can be broken down into four parts: setting a starting location, setting an end destination, previewing the generated route to see if it suits the user’s needs, and checking if the user is correctly following the route (and perhaps triggering a new one if not). Indoor wayfinding faces several challenges in providing those features:

• Locations such as airports or hospitals might not yet have digital maps available to support wayfinding.
• GPS technology, which is crucial to outdoor routing and tracking, will often not work indoors, forcing indoor wayfinding solutions to find a different approach to location sensing.
• Buildings might have multiple levels or floors, with the same GPS coordinate occurring on each one. Methods of moving between levels (lifts, escalators, stairs, moving walkways) are typically not understood by outdoor routing algorithms.
• Indoor places often have distinctive constraints that need to be considered, such as closing times, or restricted access without a boarding ticket.

Solutions Available Today for Indoor Wayfinding

People visiting labyrinthine indoor spaces like huge office blocks and airports for the first time can easily get lost without the help of navigation tools. That might just be frustrating but it could also mean arriving late for a meeting or missing a plane. Furthermore, those with different access needs, such as mobility issues, may face additional barriers to navigating complex buildings e.g. insufficient information available about the space.

Indoor wayfinding aims to resolve challenges such as these. Luckily, there are solutions out in the market that can help, at least in part. Here, I’ve listed a few considerations for indoor wayfinding and some interesting products:

1. Mapping Indoor Spaces

The first challenge is to find representations of the the indoor space – maps – that provide a foundation for wayfinding. Here are three interesting approaches to that problem:

Extending Outdoor Maps Indoors

The most common approach is to extend familiar-looking maps from outdoors to indoors through scaled and compass-aligned floor plans for each level of a building, as supported by Google’s Indoor Maps. It’s up to the building owner to upload and update their floor plans, though there are lots of third party providers happy to help.

The familiarity of the birds-eye-view map representation is a great help for users that eases transitions between outdoors and indoors. However, the aligned map will not itself automatically provide indoor routing or reflect place-specific constraints, and availability is currently restricted to desktop and Android users.

Creating 3D Models or Video Tours

Another approach is to provide a visual representation of a building’s interior either as a 3D model or a video tour. The Colosseum in Rome, for instance, can be ‘visited’ through this approach.
On the plus side, this approach is great if a user wants to get a feel of the building and plan routes before visiting. However, that only works if they have the time to explore the virtual building beforehand, and again there is no “built-in” routing or place-specific constraints.

Mapping The Inside of a Building as Distinctive Landmarks

Calvium pioneered a third approach for UCAN GO – an indoor wayfinding app intended for users with impaired vision (but that can be used by anyone). We map the inside of a building as a network of visually-distinctive landmarks with descriptions of the links between them. 

Routes are found between landmarks by following links through the network, carefully respecting constraints such as the need to avoid stairs. Our approach enables users to make independent visits to cultural venues that might not currently have floor plans or indoor location sensing. On the other hand, our users do need to initially tell the app where they are by identifying a nearby landmark, and the app doesn’t give an overview of the building’s layout in the way that a floor plan would.

2. Location sensing

The second big challenge is to detect where someone is in a building, for example to set a starting location or ensure the user is on the right track. Although GPS is problematic indoors, location sensing can still be done through the use of radio technologies like WiFi and Bluetooth:

WiFi positioning

With WiFi positioning, mobile devices work out their user’s location based on the strength or simply the presence of signals they receive from nearby access points (APs). Current WiFi technology can provide 10-20m accuracy, but the new round-trip timing (RTT) capability could reduce that to 1-3m when it is rolled out. One early adopter is Poland’s Posnia Shopping Mall which uses WiFi positioning for an indoor location solution that can be conveniently accessed through any browser.

The great advantage of WiFi positioning is that it exploits existing network infrastructure and APs, although new APs might be also needed for coverage and accuracy. It can also detect which floor level a user is on. However, the approach does need the locations of APs to be accurately surveyed and maintained, and there are limitations to its use on iOS. 

Bluetooth Positioning

Bluetooth positioning works essentially in the same way as WiFi but uses small, cheap, and power-efficient beacons rather than existing WiFi access points. It can provide 1-2m accuracy and low latency (the time needed to detect location). Gatwick Airport has recently installed 2,000 beacons to power their AR-based navigation app.

Bluetooth positioning is fast and its accuracy is high. On the downside, it does require lots of beacons to be installed, surveyed, and maintained, with potentially challenging logistics.

WiFi and Bluetooth positioning are the most common approaches to indoor location-sensing today, but other candidate technologies are also emerging such as ultra-wideband (which the iPhone 11 now features) and visible light communications. We can expect continued innovation in this area.

NavSta: Indoor Wayfinding for People with Invisible Impairments 

Indoor navigation can be highly challenging for those with invisible impairments such as autism, dementia or dyslexia. This gap in the market is exactly what Calvium aimed to fill with our project NavSta — a wayfinding app that will help passengers with hidden impairments find their way through railway stations. 

Based on the approach pioneered in UCAN GO, NavSta guides rail passengers through stations in short, clear steps between visually-distinctive landmarks. Routes are generated according to the user’s preferences (e.g. to avoid stairs or lifts), and the user can be directed to the nearest help point or exit should the journey become overwhelming.

One important design consideration that we had to keep in mind was the limited nature of digital infrastructure in underground stations. Our solution intentionally doesn’t require floor plans or location-sensing technology, and was designed to work with intermittent or no network connectivity when users are underground. Maps and related information are cached in the app before entry to the station and updated when a user’s phone connects to a network again.

Successful user trials at Canada Water station demonstrate the value of those design choices and the potential of NavSta to help people with disabilities make their way through rail stations and similar environments.

The Future of Indoor Wayfinding 

Although creating mobile solutions for indoor wayfinding is still more challenging than for outdoor navigation, there are solutions available today. We believe these are likely to evolve rapidly and cover more and more indoor spaces each year. The challenges now are to identify the approach that best fits the nature of a particular indoor space, and to ensure that the solution is inclusive and works for everyone. We at Calvium would love to help. 

NavSta was funded by the Department for Transport through the First of a Kind Round 2 competition, delivered by InnovateUK.