9,206 research outputs found
Fast Hydraulic Erosion Simulation and Visualization on GPU
International audienceNatural mountains and valleys are gradually eroded by rainfall and river flows. Physically-based modeling of this complex phenomenon is a major concern in producing realistic synthesized terrains. However, despite some recent improvements, existing algorithms are still computationally expensive, leading to a time-consuming process fairly impractical for terrain designers and 3D artists. In this paper, we present a new method to model the hydraulic erosion phenomenon which runs at interactive rates on today's computers. The method is based on the velocity field of the running water, which is created with an efficient shallow-water fluid model. The velocity field is used to calculate the erosion and deposition process, and the sediment transportation process. The method has been carefully designed to be implemented totally on GPU, and thus takes full advantage of the parallelism of current graphics hardware. Results from experiments demonstrate that our method is effective and efficient. It can create realistic erosion effects by rainfall and river flows, and produce fast simulation results for terrains with large sizes
Experimental validation of some basic assumptions used in physically based soil
In spring 2009, four rill experiments were accomplished on a fallow land. Most external factors as well as discharge quantity (9 L min-1) were held constant or at least in the same range. Following most process based soil erosion models, detachment or runoff values should therefore be similar, but the experimental results show clear differences in sediment concentration, runoff and other measured and calculated values. This fact underlines the problems of process based models: concerning rill erosion, different processes take part and the process described by the models is only responsible for a part of the eroded material
Real-time lattice boltzmann shallow waters method for breaking wave simulations
We present a new approach for the simulation of surfacebased fluids based in a hybrid formulation of Lattice Boltzmann Method for Shallow Waters and particle systems. The modified LBM can handle arbitrary underlying terrain conditions and arbitrary fluid depth. It also introduces a novel method for tracking dry-wet regions and moving boundaries. Dynamic rigid bodies are also included in our simulations using a two-way coupling. Certain features of the simulation that the LBM can not handle because of its heightfield nature, as breaking waves, are detected and automatically turned into splash particles. Here we use a ballistic particle system, but our hybrid method can handle more complex systems as SPH. Both the LBM and particle systems are implemented in CUDA, although dynamic rigid bodies are simulated in CPU. We show the effectiveness of our method with various examples which achieve real-time on consumer-level hardware.Peer ReviewedPostprint (author's final draft
A particle-based dissolution model using chemical collision energy
We propose a new energy-based method for real-time dissolution simulation. A unified particle representation is used for both fluid solvent and solid solute. We derive a novel dissolution model from the collision theory in chemical reactions: physical laws govern the local excitation of solid particles based on the relative motion of the fluid and solid. When the local excitation energy exceeds a user specified threshold (activation energy), the particle will be dislodged from the solid. Unlike previous methods, our model ensures that the dissolution result is independent of solute sampling resolution. We also establish a mathematical relationship between the activation energy, the inter-facial surface area, and the total dissolution time - allowing for accurate artistic control over the global dissolution rate while maintaining the physical plausibility of the simulation. We demonstrate applications of our method using a number of practical examples, including antacid pills dissolving in water and hydraulic erosion of non-homogeneous terrains. Our method is straightforward to incorporate with existing particle-based fluid simulations
Shape Animation with Combined Captured and Simulated Dynamics
We present a novel volumetric animation generation framework to create new
types of animations from raw 3D surface or point cloud sequence of captured
real performances. The framework considers as input time incoherent 3D
observations of a moving shape, and is thus particularly suitable for the
output of performance capture platforms. In our system, a suitable virtual
representation of the actor is built from real captures that allows seamless
combination and simulation with virtual external forces and objects, in which
the original captured actor can be reshaped, disassembled or reassembled from
user-specified virtual physics. Instead of using the dominant surface-based
geometric representation of the capture, which is less suitable for volumetric
effects, our pipeline exploits Centroidal Voronoi tessellation decompositions
as unified volumetric representation of the real captured actor, which we show
can be used seamlessly as a building block for all processing stages, from
capture and tracking to virtual physic simulation. The representation makes no
human specific assumption and can be used to capture and re-simulate the actor
with props or other moving scenery elements. We demonstrate the potential of
this pipeline for virtual reanimation of a real captured event with various
unprecedented volumetric visual effects, such as volumetric distortion,
erosion, morphing, gravity pull, or collisions
Unified Mechanical Erosion Model for Multi-phase Mass Flows
Erosion poses a great challenge in multi-phase mass flows as it drastically
changes flow behavior and deposition pattern by dramatically increasing their
masses, adversely affecting population and civil structures. There exists no
mechanically-explained, unified multi-phase erosion model. We constitute a
novel, unified and comprehensive mechanical erosion rates for solid and fluid
phases and demonstrate their richness and urgency. This is achieved by
seminally introducing interacting stresses across erosion-interface. Shear
resistances from the bed against shear stresses from the landslide are based on
consistent physical principles. Proposed multi-phase interactive shear
structures are mechanically superior and dynamically flexible. Total erosion
rate is the sum of solid and fluid erosion rates which are mechanically
extensive and compact. Erosion rates consistently take solid and fluid
fractions from the bed and customarily supply to solid and fluid components in
the flow. This overcomes severe limitations inherited by existing models. For
the first time, we physically correctly construct composite, intricate erosion
velocities of particle and fluid from the bed and architect the complete net
momentum productions that include all interactions between solids and fluids in
the landslide and bed. We invent stress correction, erosive-shear-velocity,
super-erosion-drift and erosion-matrix characterizing complex erosion
processes. By embedding well constrained extensive erosion velocities, unified
erosion rates and net momentum productions including erosion-induced inertia
into mass and momentum balances, we develop a novel, mechanically-explained,
comprehensive multi-phase model for erosive mass flows. As new model covers a
broad spectrum of natural processes it offers great opportunities for
practitioners in solving technical, engineering problems related to erosive
multi-phase mass flows
Creating landscapes with simulated colliding plates
The creation of realistic virtual terrain has been a longstanding computer graphics problem, as terrain will form the backdrop of any virtual world. Approaches to this problem to date have taken one of two approaches: either fractally generating landscapes, or simulating the processes of water and thermal erosion. I have developed a new method to synthesize virtual landscapes, by simulating some of the geological forces that create real-world landscapes
I model the collision and deformation of simulated tectonic plates, and create features that mimic those found along real-world plate boundaries. This is achieved through the use of a meshless object representation subjected to physically-based forces, using existing techniques for accurately modeling stress and strain in solid objects
Interactive Procedural Modelling of Coherent Waterfall Scenes
International audienceCombining procedural generation and user control is a fundamental challenge for the interactive design of natural scenery. This is particularly true for modelling complex waterfall scenes where, in addition to taking charge of geometric details, an ideal tool should also provide a user with the freedom to shape the running streams and falls, while automatically maintaining physical plausibility in terms of flow network, embedding into the terrain, and visual aspects of the waterfalls. We present the first solution for the interactive procedural design of coherent waterfall scenes. Our system combines vectorial editing, where the user assembles elements to create a waterfall network over an existing terrain, with a procedural model that parametrizes these elements from hydraulic exchanges; enforces consistency between the terrain and the flow; and generates detailed geometry, animated textures and shaders for the waterfalls and their surroundings. The tool is interactive, yielding visual feedback after each edit
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