N. Chotikakamthorn

King Mongkut's Institute of Technology Ladkrabang

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Co-Authors

Natapon Pantuwong

King Mongkut's Institute of Technology Ladkrabang

Olarn Wongwirat

King Mongkut's Institute of Technology Ladkrabang

Nontapol Somrang

King Mongkut's Institute of Technology Ladkrabang

Narongsak Phutphuek

King Mongkut's Institute of Technology Ladkrabang

Jonathon A. Chambers

University of Leicester

Shigeyuki Ohara

Tokai University

Pornchai Kanjanasupark

King Mongkut's Institute of Technology Ladkrabang

S. Pholsomboon

Chulalongkorn University

N. Hongboonme

King Mongkut's Institute of Technology Ladkrabang

Hiroshi Suzuki

Tokushima University

Cooperative Institutions

King Mongkut's Institute of Technology Ladkrabang

King Mongkut's University of Technology North Bangkok

Tokai University

University of Leicester

Newcastle University

University Elmergib

Harbin Engineering University

New Horizons Diagnostics (United States)

University of Lincoln

Loughborough University

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Multimodal Synchronization for Human-Machine Interaction in Virtual Environment

International Conference on Information Technology and Applications (2002)

Olarn Wongwirat N. Chotikakamthorn Sean M. O'Hara

Multimodal Interaction

Human interaction

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Seeing by drawing: use of a force-feedback device for conveying basic geometric visual information

N. Chotikakamthorn N. Hongboonme

In this paper, the problem of using a force-feedback device to display basic geometric information is considered. Two visual-haptic transformation methods are applied to display geometric-shape properties by a point-contact force-reflective device. With the first method, movement of a user's finger tip, attached to a force-feedback device's thimble, is limited to points on a contour representing an outline of the (1-D or 2-D) geometric shape under display. In the second method, a drawing force is applied to a thimble, to move a user's finger along the contour corresponding to the displayed shape. Drawing speed is adjusted to reflect some properties of the displayed data curve, such as evolution of its first or second derivatives over time or spatial reference axis. Implementation aspects of the two methods are discussed. Efficiency of the described haptic display methods has been investigated through experiments with basic geometric outline shapes and scientific data.

Geometric transformation

Transformation geometry

Geometric Modeling

Stereotaxy

Visual feedback

10.1109/icsmc.2000.885968

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Interactive Haptic Simulation of Dental Plaque Removal

International Symposium on Communications and Information Technologies (2006)

Nontapol Somrang N. Chotikakamthorn

This paper discusses the development of an interactive training system which performs haptic simulation for practicing dental plaque removal. Three object types are simulated, namely teeth, plaque, and gums. All of them can be interacted with through a single-point-of-contact haptic device. A tooth is modeled as a rigid-body object, while gums are modeled as a deformable object. A method has been developed for dental plaque simulation, based on a physically-based modeling of fragile material. Plaque is modeled as a set of point-masses connected by bonds which represent distance-preserving linear constraints. Some bonds are used to connect pieces of plaque together, while others are used to bind the plaque with teeth. The forces exerted on these bonds during impact are computed based on a spring-mass model of plaque object. The resulting force is compared with each bond strength to determine when and where plaque fragmentation occurs

Dental plaque

10.1109/iscit.2006.340055

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Citations (5)

Query decomposition method for multi‐keyword search in P2P systems

Electronics Letters (2015)

N. Chotikakamthorn Tanapon Jitnupong

A problem of multi‐keyword search in a structured peer‐to‐peer (P2P) distributed computing system is considered. Methods have been developed to employ term‐set indexing in a P2P system. Such an approach is an attempt to avoid excessive communication cost incurred by intersection operations in a single‐term indexing method. In addition to limiting the maximum term‐set size, index pruning was proposed to avoid exponential growth of the term‐set index size. However, to obtain a global search result, query decomposition and query result intersection operations are still needed when the number of query terms exceeds the maximum term‐set size. With index pruning employed, how a multi‐term query is decomposed and affects the quality of retrieval results in terms of recall and precision is shown. A near‐optimal query decomposition method is proposed to alleviate such a problem. Results from the simulation demonstrate the improvement gained by the proposed method.

10.1049/el.2014.2467

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An interatvie stereoscopic viewing system using fast vision-based leg end-point position estimation

Narongsak Phutphuek N. Chotikakamthorn

In this paper, a problem of interactive stereoscopic display is considered. To provide a stereo image pair with correct viewing angle, a stereoscopic system must be able to identify a viewer spatial location. A fast and low-cost viewer location estimation method using a single video camera is described in this paper. The method tracks a viewer’s standing position by estimating his/her leg end-point on the floor. The so-obtained position is then transformed to a 3D coordinate by using a planar homographic projection. Because the estimated viewer position is noisy, a smoothing and semiinteractive updating algorithm is developed to reduce a flicker caused by the imprecise estimate.

Position (finance)

Smoothing

10.1109/isspa.2005.1581017

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Comparative Study of Two Projective-Invariant Digital Watermarking Methods Using Cross-Ratios and Line Intersections

Natapon Pantuwong N. Chotikakamthorn

Recently, based on a set of four coplanar points, a projective-invariant digital watermarking has been developed. A combination of line intersection and the cross-ratio relationship of collinear points is used to calculate watermarking embedding locations. The four coplanar points used to derive embedding locations can be obtained from either the image corners or the feature points extracted from the image content. It is shown in this paper that based on the same principle, an alternative algorithm for calculating the watermark embedding locations improves computational efficiency. The proposed method heavily uses the cross-ratio relationship of collinear points, while minimizing the use of line intersection in obtaining embedding locations. This is in contrast with the original method, where embedding locations are mainly obtained from intersections of line pairs. Both analytical and experimental results are provided to demonstrate the improvement

Cross-ratio

Line (geometry)

10.1109/cit.2005.88

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Citations (2)

Projective-invariant digital image watermarking technique using four co-planar feature points

N. Chotikakamthorn Natapon Pantuwong Wiyada Yawai

The problem of digital image watermarking invariant to planar projective transformation is considered in this paper. Methods that are invariant to certain spatial transformations, such as 2D geometric, and a more general affine transformation, are now widely available. However, those methods fail if a possibly watermarked image has undergone a projective transformation. A method based on a well-known projective invariant property of triangle area ratios, constructed from a set of four co-planar feature points, is described in this paper. The proposed method makes use of such invariant property to compute watermark embedding locations. Formation of the required four feature points for such computation is described. Experimental results are shown to demonstrate failure of an existing affine-invariant watermarking method even at very small projective distortion, as well as the success of the proposed method in withstanding distortion due to the same transformation over wide projection angles.

Geometric transformation

10.1109/icip.2005.1529923

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Citations (3)

On identifiability of OFDM blind channel estimation

N. Chotikakamthorn Hiroshi Suzuki

The technique of orthogonal frequency division multiplexing (OFDM) has received much attention as a promising scheme for use in future wireless mobile communications. A problem of blind channel estimation for coherent detection in OFDM systems is considered. It is shown in this paper that the channel is identifiable, given only a received data set obtained over one OFDM symbol duration. A sufficient condition for the channel to be identifiable is given, with outline of the proof included. In addition, a compact form of the maximum likelihood channel estimator for a PSK modulation scheme is derived. Experimental results are provided to demonstrate the performance of the proposed method.

Identifiability

Modulation (music)

10.1109/vetecf.1999.797360

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Citations (34)

A Low-cost Vision-based Leg Tracking Algorithm for an Interactive Stereoscopic System

ITC-CSCC :International Technical Conference on Circuits Systems, Computers and Communications (2005)

Narongsak Phutphuek Natapon Pantuwong N. Chotikakamthorn Olarn Wongwirat

Tracking (education)

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Fast Haptic Simulation of Brittle Object using Bounded Force Propagation Model

International Symposium on Communications and Information Technologies (2008)

Nontapol Somrang N. Chotikakamthorn Siraset Jirapatchandej

In this paper, a method for real-time simulation of brittle object with haptic force feedback is described. Based on the rigid-constraint model, originally developed for visual-only image synthesis, a virtual object is represented as a set of point-masses connected by distance-preserving linear constraints. The drawback of the original method is that it is time consuming and not suitable for real-time haptic simulation. In this paper, a bounded force propagation model is developed to reduce calculation time as required by the original method. In addition, a haptic-endpoint position prediction method is applied to prepare the simulation system for the calculation required by the method. These refinements allow the brittle object simulation method to be applicable to real-time interactive applications with haptic force feedback.

Real-Time Simulation

Virtual image

10.1109/iscit.2008.4700260

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