Using SenseCam to pursue “ground truth” for global positioning system travel surveys

• Visual images are firstly introduced in travel demand data collection.
• SenseCam could help GPS data collection to obtain ground truth.
• This paper provides a potential way to collect travel demand data in the future.
• The performance of GPS devices is examined in detail.
• An in-depth analysis on the reasons of missing GPS data is undertaken.

Global Positioning System (GPS) surveys have been conducted for the past decade. Although GPS records were initially regarded as providing “ground truth” of travel, it has been found subsequently that they have some errors. SenseCam, a small passive digital camera, provides a chance to pursue ground truth by capturing images every 20 s on average. This paper discusses how SenseCam could help GPS data collection and shows potential benefits for both SenseCam and GPS research. This paper also investigates the performance of GPS devices in detail in terms of recording data by comparisons between GPS results and SenseCam images. The specific issue of missing GPS data is discussed and examined in this paper.