Eurographics Workshop on Natural Phenomena (2009)
E. Galin and J. Schneider (Editors)
Real-Time Open Water Environments
with Interacting Objects
H. Cords and O. Staadt
Visual Computing Group, University of Rostock, Germany
Abstract
Large bodies of water are an integral part of nature and, thus, are of high interest for interactive 3D applica-
tions, e.g., computer games and virtual environments. We present a new scheme for real-time wave simulation in
large-scale water environments with physics-based object interaction. In addition to a fast and realistic liquid rep-
resentation, our method focuses on the creation of plausible detailed waves caused by moving boats. We expand
the well-known wave equation by applying it to moving grids to simulate an apparently limitless body of water.
Additionally, we present a fast, particle-based boat simulation, which is coupled to water simulation. Importantly,
most parts of our method can be implemented efficiently on GPUs. We demonstrate the visual realism and perfor-
mance of our approach with several experiments using different boats and other floating objects, achieving high
frame rates on a desktop PC.
Categories and Subject Descriptors
(according to ACM CCS): Computer Graphics [I.3.7]: Three-Dimensional
Graphics and Realism—Animation
1. Introduction
Simulation of complex, physics-based liquid effects has be-
come a staple in the field of computer animation and visual
simulation. Today’s offline-methods are realistically and de-
tailed, but computational cost is very high. Due to the com-
plexity of fluid physics in principle, achieving comparable
realism in real-time is an ongoing challenge that is aided by
the increasing performance of today’s GPUs.
This paper describes a method to simulate interactive
large-water environments that supports detailed surfaces
with focus on object-wave interaction. We expand differ-
ent techniques to achieve high-quality results in real-time.
We reduce complexity by applying an adaptive height field-
based method. It is based on the 2D wave equation and is
solved using a finite difference method (FDM). Thus, a fine
discretization can be used for simulation – even in interactive
environments. Using a moving grid method, detailed simula-
tion is carried out only in areas where it is needed. We extend
the approach to the use of multiple grids to obtain an adap-
tive simulation. Additionally, we describe an efficient boat
simulation and a two-way coupling with liquids simulation.
Hence, realistic boat movements and boat waves can be cre-
ated. The scheme has been evaluated in practice, achieving
good performance and realistic results due to extensive use
of the GPU. The approach is suited for real-time environ-
ments such as VR environments or video games.
2. Related Work
Interactive simulation of liquids can be classified into
surface- and volume-based techniques. The latter apply the
Navier-Stokes-Equations in 3D to model the liquid’s phys-
ical flow properties. In interactive computer graphics, the
equations are typically solved using an efficient finite differ-
ence method [Sta99] or smoothed-particle hydrodynamics
(SPH) [MCG03]. Adaptive couplings of 3D free surface sim-
ulations with 2D simulations have been presented to increase
performance [TRS06, Cor07]. An SPH simulation coupled
with a rigid-body simulation was presented in [Ama06].
GPU-based implementations of 3D simulations pushed the
limit of virtual liquids realism [Har04, HKK07, CIS07]. The
use of adaptive domain translation within a 3D fluid sim-
ulation is presented in [SCP
∗
04]. Our work uses a domain
translation within a 2D FDM simulation as well to reach an
adaptive representation at high performance. Surface extrac-
c
The Eurographics Association 2009.