# The Usage of Virtual and Augmented Reality in Underwater Archeology
## 3 Virtual and Augmented Reality Technologies
### Creating Virtual or Augmented Reality Applications for Underwater Archeology  
The process of creating applications in the field of underwater archeology, unlike other applications, is based on specific methods of collecting scientific data using methods specific to underwater research. Creating an application consists of many tasks. Generally, the entire process can be divided into three stages (Figure 2). These are the following:  
1. Collecting information about an object, where an object will be both a single artifact, e.g., a shipwreck, and the entire archaeological site from which we will process data in order to obtain a 3D visualization. Additionally, at this stage, additional information should be defined, i.e., the group of recipients that may influence the technologies used. 2. Processing the data into a three-dimensional reconstruction of an archaeological site and/or set of artifacts. Objects can be described using a set of points in three-dimensional space, a map of normal vectors describing the object, as well as a map of surface gradients obtained in the shape reconstruction process. The third technique has the widest application [32]. 3. Preparing an appropriate form of information transfer using AR or VR, e.g., in the form of an application containing elements of AR. Figure 1: The history of the development of VR/AR and their application in underwater archaeology. Figure 2: Diagram of the process of creating virtual and augmented reality applications. The first stage is usually collecting information about the facility, which most often begins with obtaining general information, followed by collecting detailed data and carrying out measurements. The first data point about the archaeological sites may come both from regular surveys and from reports by amateur divers or local people [26]. After confirming the reliability of the information, preliminary research is usually carried out at a given site in order to confirm the credibility of the reports and confirm the archaeological character of the site. Only then are fundamental works planned to collect information about the archaeological site and document it. Broadly speaking, the methods used at this stage can be divided into two groups--visual methods and acoustic (hydroacoustic) methods. Additionally, in this division, we can distinguish a third group of other methods that do not fit into any of the above groups (Figure 3). Methods based on acoustics include the following: one-beam echosounders, side-scan sonars, and multi-beam sonars [32]. Among hydroacoustic methods, side sonars and multi-beam probes are most often used for the accurate reconstruction of archaeological sites due to the fact that they allow for observing of the bottom of the site with high resolution and for obtaining image quality similar to photography [32]. In the case of multi-beam equipment, the software attached to the device often has the ability to visualize the obtained image in three-dimensions. Measurements with multi-beam probes are used, among others, for making detailed profiles of the seabed and support research in the field of underwater archaeology. They were used, among others, at an underwater archaeological site in the Gulf of Pozzuoli (Naples, Italy), allowing to obtain additional information about archaeological sites, i.e., Secca delle Fumose and Villa dei Pisoni [42]. In images obtained from side measurements, we most often receive two-dimensional data that resemble black-and-white photos. These data require the use of various image analysis methods, which then allow for obtaining three-dimensional visualization [32]. Side-scan sonar research combined with other methods has been used, among others, in work on the documentation of the Roman port of Nisida, the Roman port of Marechiaro, and the remains of the [PERSON] villa [43]. It is worth noting that in turbid waters, hydroacoustic methods have an advantage over visual methods because they are not sensitive to the degree of water transparency [32; 44].