A comparative study of tracking methods for a guided walking city tour in outdoor spaces for tourists through AR on smartphones.

Abstract: Recent advancements in mobile phone technology have al- lowed mobile augmented reality (MAR) to become feasible. Today’s mobile phones have enough computing power to dis- play augmented reality content and new frameworks make MAR development more accessible. It is no surprise that one of the most popular areas of applications are city tours as this has been a target field since the early days of aug- mented reality (AR) [8]. Without altering the appearance of the city, virtual content can be placed to bring hidden information, such as the city’s history, closer to tourists. The most common choice of the tracking method for this type of application is location-based tracking. Relying only on the GPS signal and sensors like the accelerometer and the gyroscope, the position of the phone is tracked. The location of the digital content in the real world is given by geospatial coordinates. Unfortunately, the accuracy of the sensors is insu⇥cient for accurate placement. Furthermore, the technology’s main advantage over other techniques, such as marker-based tracking, is that the application does not require any change in the city environment. In contrast to that, the other leading technique, marker-based tracking, is a computer vision technology that requires visual clues to work. Marker images would have to be placed in the city for the marker-based tracking technology to function. How- ever, location-based tracking can cause erratic behaviour of the virtual objects, which decreases the quality of the ex- perience. This paper compares location-based and marker- based tracking to show the user experience strengths and weaknesses of both methods to provide design guidelines for choosing the most suitable tracking technology when de- veloping an outdoor walking application. In order to un- cover the strengths and weaknesses, one experimental proto- types for each tracking technology has been developed. The analysis of the results of a controlled user study highlights the comparative strengths and weaknesses of each technol- ogy, location-based and marker-based tracking. The mea- sured user experience di⇤erences demonstrate that for scenes where AR application designers and city o⇥cials are lead- ing to incorporate visual markers, visual-based tracking will outperform location-based tracking.