The data from National Statistics Office (NSO) of Thailand show that 543,332 people in Thailand are blind or visually impaired (2007). Even though, many navigation devices are made for visually impaired people, the vast majority of the devices are expensive and available only in some country. Therefore, iPhone, which is one of the most popular GPS-enabled smart phones today is selected as a platform for the development of the navigation system for the blind and visually impaired.