In this paper, we propose a new interface to control VR(Virtual reality) contents, games, and animations in real-time using the user’s breath and the acceleration sensor of a mobile device. Although interaction techniques are very important in VR and physically-based animations, UI(User interface) methods using different types of devices or controllers have not been covered. Most of the proposed interaction techniques have focused on screen touch and motion recognition. The direction of the breath is calculated using the position and angle between the user and the mobile device, and the control position to handle the contents is determined using the acceleration sensor built into the mobile device. Finally, to remove the noise contained in the input breath, the magnitude of the wind is filtered using a kernel modeling a pattern similar to the actual breath. To demonstrate the superiority of this study, we produced real-time interaction results by applying the breath as an external force of VR contents, games, and animations.

In this paper, we propose a method to efficiently control the path of non-playable characters (NPC) in an interactive virtual environment such as a game or virtual reality (VR) by calculating a weight map and path similarity based on the user’s path. Our method automatically constructs a navigation mesh that provides a new route to the NPC by referring to the user’s trajectory. Our method finds more paths that users usually go through as time passes, and the number of users increases. Accordingly, the paths that NPCs can traverse automatically are updated adaptively to the virtual environment. In addition, NPC agents can move smartly by assigning high weights to the user’s preferred paths. We tested the usefulness of the proposed method through several example scenarios in an interactive environment such as a video game or VR, and this method can be easily applied to various types of navigation based on the interactive environment.

In this paper, we propose a sprite animation synthesis technique that can efficiently represent the fire-flake effects seen in the natural phenomenon of fire. The proposed method uses the actual fire video or animated fire video as inputs and performs the following steps: 1) Extraction of feature vectors that can predict the direction of flame from image, 2) calculation of artificial buoyancy field, 3) creation and advection of fire-flake texture, 4) calculation of artificial motion blur using buoyancy flow, and 5) high quality composition. First, we detect the edges from the image and calculate the feature vectors needed to calculate the artificial buoyancy field. The computed 2D feature vectors are integrated into the Navier-Stokes equation and used to calculate the buoyancy field, which generates and advects anisotropic fire-flake textures. Finally, we apply artificial motion blur according to buoyancy direction to improve composition result of sprite animation. As a result, this method is based on image synthesis, which is faster than the existing 3D simulation-based approach. Experimental results show that high quality results can be easily and reliably obtained. In addition, since the final result is a sprite animation format, it can be easily used in existing game engines.

In this paper, we propose an angular momentum-based advection technique that can express the turbulent foam effect. The motion of foam particles, which are strongly bound to the motion of the underlying fluid, is viscous, and sometimes clumping problems occur. This problem is a decisive factor that makes it difficult to express realistic foam effects. Since foam particles, which are secondary effects, depend on the motion of the underlying water, in order to exaggerate the foam effects or express more lively foam effects, it is inevitable to tune the motion of the underlying water and then readjust the foam particles. Because of such a cumbersome process, the readjustment of the foam effects requires a change in the motion of the underlying water, and it is not easy to produce such a scene because the water and foam effects must change at the same time. In this paper, we present a method to maintain angular momentum-based force from water particles without tuning the motion of the underlying water. We can restore the lost turbulent flow by additional advection of foam particles based on this force. In addition, our method can be integrated with screen-space projection frameworks, allowing us to fully embrace all the advantages of this approach. In this paper, the turbulence of the foam particles was improved by minimizing the viscous motion of the foam particles without tuning the motion of the underlying water, and as a result, lively foam effects can be expressed.