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Abstract-Present day pedometer applications lack the ability to identify and measure each step for individual data with high precision. The rapid growth and evolution in the capacity of today's smartphones now present the opportunity to investigate new methods that gives the possibility to measure each individual step, providing data such as length, width and time by using an out of shelf smartphone. This paper introduces the Optical Pedometer (OP for short) that differs from traditional smartphone pedometer applications in the way that it is based on computer vision, providing new possibilities as to actually identify and measure steps with help of the phone's camera. Our proposed method was evaluated and compared to the existing methods within this field; accelerometer based pedometers and GPS applications. The results showed that the OP method presented more accurate measurements, thus proving it applicable for shorter measurements requiring a higher degree of accuracy.
Keywords: android, pedometer, computer vision, distance measuring
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1. Introduction
Measuring traveled distances with your smartphone is a popular concept used in contemporary applications predominantly within areas concerning health, exercise and recreation.
To measure covered distances the system rely on either one or two of the phone's sensors: the Global Positioning System (GPS) sensor and the accelerometer. The GPS sensor in the phone sends information about the current position in form of coordinates. The length between the coordinates can then be calculated to give an account for the total distance traveled. The accelerometer, on the other hand, is often used to create a step counter or pedometer which identifies changes in the signal provided by the accelerometer to detect when a step has been taken [12]. The total number of steps is then multiplied with the users estimated average step length resulting in an assessment of the total distance walked.
However, none of these methods works well for measuring shorter distances to any high degree of accuracy. For example the GPS approach is used for most exercise applications and works well for longer distances as its accuracy improves the further the distance you travel. However, according to the American Department of Defense [2] the public civilian GPS type called Standard Positioning Service (SPS) hold a horizontal accuracy of 7.8 meter (95...