We propose a novel method to enhance a family of ICP(iterative closest point) algorithms by updat... more We propose a novel method to enhance a family of ICP(iterative closest point) algorithms by updating velocity. Even though ICP algorithms play a dominant role in a model based tracking, it is difficult to avoid an accumulated tracking error during a continuous motion. It is because that typical ICP algorithms assumes that each of the point in one scan are
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2013
Traditional Euler angle-based methods for the kinematic and dynamic modeling of spherical joints ... more Traditional Euler angle-based methods for the kinematic and dynamic modeling of spherical joints involve highly complicated formulas that are numerically sensitive, with complex bookkeeping near local coordinate singularities. In this regard, exponential coordinates are known to possess several advantages over Euler angle representations. This paper presents several new exponential coordinate-based formulas and computational procedures that are particularly useful in the modeling of mechanisms containing spherical joints. Computationally robust procedures are derived for evaluating the forward and inverse formulas for the angular velocity and angular acceleration in terms of exponential coordinates. We show that these formulas simplify the parametrization of joint range limits for spherical joints, and lead to more compact equations in the forward and inverse dynamic analysis of mechanisms containing spherical joints.
This paper presents a coordinate-invariant differential geometric analysis of kinematic singulari... more This paper presents a coordinate-invariant differential geometric analysis of kinematic singularities for closed kinematic chains containing both active and passive joints. Using the geometric framework developed in Park and Kim (1996) for closed chain manipulability analysis, we classify closed chain singularities into three basic types: (i) those corresponding to singular points of the joint configuration space (configuration space singularities), (ii) those induced by the choice of actuated joints (actuator singularities), and (iii) those configurations in which the end-effector loses one or more degrees of freedom of available motion (end-effector singularities). The proposed geometric classification provides a high-level taxonomy for mechanism singularities that is independent of the choice of local coordinates used to describe the kinematics, and includes mechanisms that have more actuators than kinematic degrees of freedom.
We present an efficient, user-guided volumetric approximation algorithm, specifically designed fo... more We present an efficient, user-guided volumetric approximation algorithm, specifically designed for physically-based animation. Our method combines automatic and interactive segmentation methods to give users an intuitive and easy way to approximate 3D meshes. Our approach first constructs the simplified medial axis transform (MAT) of the input mesh object, and segments the medial axis (MA) into parts in terms of swept sphere volumes (SSVs) using a region growing method. Then, we decompose the object surface into regions based on the mapping between the segmented MA and the object surface. Each segmented region is approximated with a SSV. These decomposed surface regions can be interactively refined further by splitting and/or merging using a sketch-based input. Experimental results show that our approach produces good volumetric approximation results for different types of object shapes. Moreover, rigid-body dynamics simulation based on our volumetric approximation provides a visually pleasing result.
To simulate solid dynamics, we must compute the mass, the center of mass, and the products of ine... more To simulate solid dynamics, we must compute the mass, the center of mass, and the products of inertia about the axes of the body of interest. These mass property computations must be continuously repeated for certain simulations with rigid bodies or as the shape of the body changes. We introduce a GPU-friendly algorithm to approximate the mass properties for an arbitrarily shaped body. Our algorithm converts the necessary volume integrals into surface integrals on a projected plane. It then maps the plane into a ...
In this paper, we address the problem of designing and implementing low-cost yet effective user i... more In this paper, we address the problem of designing and implementing low-cost yet effective user interfaces for interactive computer games that heavily use physically-based animation. Due to the nature of a physics-driven gaming setup in our system, we require that the interfaces should mimic the tangibility of real-world interfaces to maximize the playability of the game. Our prototype gaming system, called Space Foosball, is a virtual realization of the real-world foosball in a space-age setting. The biggest challenge to build our system was to design effective and robust interfaces to control the motion of user paddles, which in turn drive the physics simulation of the secondary motion between a soccer ball and the environment, and between a ball and game characters. To meet our tight development budget and schedule, we opted for off-the-shelf optical sensors as a basis of the controlling mechanism. These sensors are low-cost but provided a robust solution to our problem. Another important task to build the Space Foosball was implementing a high-performance game physics engine that suits for simulating the very dynamic foosball environment. To meet this demand, we designed and implemented an in-house physics engine, called Virtual Physics, based on a mathematical formulation of Lie groups. In less than a short period of two months, we successfully built our prototype gaming system which effectively utilizes tangible interfaces while robustly simulating the game physics environment.
Proceedings of the 2008 International Conference in Advances on Computer Entertainment Technology - ACE '08, 2008
Virtual Reality (VR) as well as Augmented Reality (AR) environment can be used as media for eduta... more Virtual Reality (VR) as well as Augmented Reality (AR) environment can be used as media for edutaining. They provide pleasant environments for educating students through experiences. In this paper, we present a 3D edutainment environment which provides an experience-based learning environment for understanding the Newtonian physics law. We design a physics-based simulation application that simulates a domino effect in the 3D environment. Using this application, the user can learn physics by interacting and experiencing different kinds of domino effect in the VR/AR environment. We propose a new way to help the user tuning the simulation conditions to produce a desired simulation effect by illustrating an expected trajectory of the object of interest. Therefore, the user can easily distinguish the simulation results from different configurations by comparing the trajectories of the selected object.
Uploads
Papers by Jinwook Kim