# Visual Navigation Systems for Maritime Smart Ships: A Survey
## 2 Smart Ships and Navigation Technology
### Smart Ships
#### 2.1.1 IMO Guidance and Industry Requirements for Smart Ships  
The concept of an smart ship, first introduced in the 19 th century, refers to a ship that is capable of carrying out a series of well-defined operations without or with a small number of crew members supervising it [5]. In order to give sustainable impetus to the development of the shipping industry in Europe, Norway was the first to develop technology for smart ships. There are three categories of more leading smart ship projects that examine the feasibility of developing viable business models in the short to medium term, reducing accident fatalities and analyzing the feasibility of smart ship scenarios [6]. Smart ships have been designed and developed for a number of reasons: to provide a better working environment for crews; to mitigate possible future crew shortages; to reduce risks in transportation; to be environmentally friendly; and to provide greater safety of navigation. The introduction of smart ships will bring about a new shift in cost efficiency, accident prevention and human resources. While smart ships are expected to be safer than conventional ships, the emergence of new technologies also brings new risks, such as the emergence of cybersecurity threats and misinformation. It is therefore important to define standards for shore-based operators of smart ships and provide relevant training. With regard to legal issues, the difference between the time it takes for technology to mature and the time it takes for regulations to be developed and put into practice may have a negative impact on the adoption of advanced technologies, and it is therefore important to recalibrate the relevant regulatory approaches. Smart ships may also raise ethical issues in emergency situations, such as problems of untimely human-machine and machine-to-machine communication, as well as when searching for and rescuing ships, crews or passengers in urgent need of help. A more comprehensive, international and harmonized approach to the development of a new regulatory framework for smart ships is important before they become fully operational. By understanding the impacts on different sectors and their associated linkages, it will be possible to prevent maritime accidents, protect the environment and maximize commercial benefits in the context of ongoing developments [7]. The International Maritime Organization (IMO) is primarily concerned with the development of international standards for the enhancement of safety and security and the protection of the marine environment [8]. The IMO therefore has a responsibility to consider the safety of international shipping for smart ships. Since the Maritime Safety Committee (MSC) placed the issue of smart ships on its agenda in January 2017, the MSC has been working to guide countries in the development and testing of autonomous navigation technologies. The development and application of smart ship technologies from 2017 to 2020 has been driven by the MSC to achieve real progress. \"Autonomous\" ships are not all similar, and the International Maritime Organization has classified MASSs into four categories [9], including ships with a crew and some automated systems (Class 1), ships with a crew that can be remotely controlled (Class 2), remotely controlled ships without a crew (Class 3), and ships capable of autonomous navigation without a crew and without human remote control (Class 4). The current standard for navigation is Class 1 vessels, whereas Class 2 vessels are supervised by on-board personnel who are ready to take over the operation of the system, so it is Class 3 and 4 vessels that could potentially pose a threat to the safety of shipping. The IMO, through its survey, and in order to safeguard the safe and environmentally friendly navigation of smart ships, decided in 2017 to carry out a Regulatory Scoping Exercise (RSE) aimed at assessing the extent to which the existing regulatory framework has been impacted in order to identify problems and gaps [10].