Visually Realistic Graphical Simulation of Underwater Cable Ori Ganoni Department of Computer Science University of Canterbury Christchurch, New Zealand at time t ori.ganoni@pg.canterbury.ac.nz Ramakrishnan Mukundan Department of Computer Science University of Canterbury Christchurch, New Zealand mukundan@canterbury.ac.nz Richard Green Department of Computer Science University of Canterbury Christchurch, New Zealand richard.green@canterbury.ac.nz ABSTRACT This paper presents different modeling considerations that are important in simulating visually realistic be- havior of underwater cables attached to remotely op- erated vehicles. The proposed methodology has been tested on highly complex models of aquatic environ- ments created using Unreal Engine 4. Current meth- ods and implementations of cable simulations that are widely used in computer graphics are generally suited only to light density mediums such as air. In this paper, we present modifications to the above model required for simulating neutrally buoyant cables in underwater environments. The simulation results presented in this paper successfully demonstrate different behavioral as- pects of flexible variable length underwater cables and their variations with respect to modeling parameters us- ing our proposed method. Keywords Robot simulation, ROV, Underwater simulation, Cable simulation, Unreal Engine 4. 1 INTRODUCTION Cables are used widely in underwater environments for power supply and communication to remote locations and to support various types of underwater structures. High tension cables are generally used to tow fishing equipment and research probes whereas low tension ca- bles and ropes are used in underwater tethered systems like Remotely Operated Vehicles (ROVs) (Figure 1). The drag introduced by the water medium and the buoy- ancy forces make the underwater cables behave differ- ently to less dense mediums like air or vacuum. For Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or re- publish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Figure 1: Visual simulation of Underwater tethered ROV most ROV cables (and also in our simulation), gravi- tational effects can be ignored since as a design goal, underwater ROV systems use neutrally buoyant cables. Simulating the behaviour of the cable attached to an ROV can be helpful in several situations such as (i) de- veloping control algorithms for avoiding cable tangling, (ii) handling vision issues when the cable is in front of the ROV’s camera, (iii) estimating the configuration of the cable in different conditions and manoeuvres, and (iv) simulating complex manoeuvres for missions in- volving multiple cables and ROVs. The behavior of a rope under external forces is gener- ally modelled as a multi-rigid-body dynamic system (or chain system), by representing the rope as long chain of segments. In order to simulate a large number of segments in real-time, we need a fast and memory ef- ficient method which need not necessarily be physi- cally accurate. At the same time, the motion should look physically realistic, and controlled by a number of parameters which defines the cable behaviour. In ad- dition, some of the unique characteristics of the water domain need to be parameterized and added to the sim- ulation model. Simulation of dynamic systems in com- puter graphics mainly use force-based methods, where linear and rotational accelerations are computed from forces and torques. A time integration method is then used to update the velocities and positions of the object. ISSN 2464-4617 (print) ISSN 2464-4625 (CD) Computer Science Research Notes CSRN 2802 Short Papers Proceedings http://www.WSCG.eu 56 ISBN 978-80-86943-41-1 https://doi.org/10.24132/CSRN.2018.2802.8