## 2 Materials and Methods
### Materials  
In this study, data were acquired from the air (from high and low altitude from aircraft and UAV), from the water surface, underwater, and from the ground surface, shown schematically in Figure 3.  
Two boats were used for hydrographic data acquisition: Hydrograf XXI (Maritime University in Szczecin) and HYDROAMPPER (from Gispro).  
The hydrographic measurements were divided into two stages. The first stage was preliminary and served as preparation and validation of hardware and software configurations. The second stage was the main stage of measurement, during which data were collected in  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**Area**} & \multirow{3}{*}{\begin{tabular}{c} **Airborne** \\ **Laser** \\ **Scanning** \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} **Airborne** \\ **Laser** \\ **Bahymetry** \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} **Mobile** \\ **Laser** \\ **Scanning** \\ **on Land** \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} **Unmanned** \\ **Aerial** \\ **Vehicle** \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} **Mobile** \\ **Surface Laser** \\ **Scanning** \\ **Onboard** \\ \end{tabular} } & \multirow{3}{*}{\
\begin{tabular}{c} **Multibeam** \\ **Echosounder** \\ **Profiler** \\ \end{tabular} } & \multirow{3}{*}{
\begin{tabular}{c} **Sub-** \\ **Sear** \\ **Sonar** \\ \end{tabular} } \\ \cline{1-1}  & & & & & & + & + & + \\ b & + & + & + & + & + & + \\ c & + & + & + & + & + & + \\ d & + & + & + & + & + & + \\ e & + & + & + & + & + & + \\ f & + & + & + & + & + & + \\ g & + & + & & + & + & + \\ h & + & + & + & & + & + \\ \hline \hline \end{tabular}
\end{table}
Table 1: Data collected using different measurement systems.  
Figure 3: Application of different measurement platforms and systems for data collection.  
the test areas. During the first stage of measurements, a single-head bathymetric system installed on the Hydrograf XXI survey boat was used for hydrographic data acquisition, which included the following:  
* Multibeam echosounder: R2 Sonic 2024 (R2 Sonic LLC, Austin, TX, USA).
* Positioning system INS: I2 NS(tm) Type I (Applanix, Oswestry, UK).
* SVS and SVP: Valeport water speed of sound sensors (Valeport, Devon, UK).  
In stage two, the equipment was mobilised on a HYDROMAPPER floating measurement unit. The unit was adapted for integrated measurements. The measurement system used in stage two was expanded with more hydrographic sensors, which mainly included a second R2 Sonic 2024 multibeam echosounder head, including the following:  
* Side-scan sonar Edgetech 4125 (EdgeTech, West Wareham, MA, USA);
* Parametric sonar Subbottom profiler (SBP) Inonam SES-2000 (Innomar Technologie GmbH, Rostock, Germany);
* Underwater positioning system USBL Easy Track (Aae Technologies, Great Yarmouth, UK;
* Heading Sensor iXblue (iXblue Inc., Denver, CO, USA).  
Aerial data collection was performed using aircraft and UAVs owned by GISPRO. (GISPROA, Szczecin, Poland) The aircraft was equipped with a Riegl VQ-880-G II (RIEGL Laser Measurement Systems GmbH, Horn, Austria) laser scanner with simultaneous green (ALB) beam measurement at 532 nm and infrared (topographic-ALS) beam measurement at 1064 nm and a medium-format camera. The Unmanned Aerial Vehicle was equipped with a hybrid combustion-electric engine and was developed specifically for this project [47]. The use of such engines allowed us to extend the flight time to two hours, and it was equipped with sensors: a laser scanner Riegl VUX-120 (RIEGL Laser Measurement Systems GmbH, Horn, Austria), INS APX-20, a Sony A7R IV camera, and a multispectral Parrot Sequoia+ (Parrot Drones, Paris, France) camera. Mobile laser scanning (MLS) and water surface laser scanning (MSLS) data were collected using a Riegl VMQ-1 HA device and VMZ-400i (RIEGL Laser Measurement Systems GmbH, Horn, Austria).