Chotikakamthorn, Nopporn

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Chotikakamthorn, Nopporn
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Chotikakamthorn, N.
Chotikakamthornb, Nopporn
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nopporn.ch@kmitl.ac.th

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    Item type:Publication,
    Performance of Bayesian-based digital matting techniques
    (2007-12-01)
    Cumpim, Chaipichit
    ;
    Chotikakamthorn, Nopporn
    Statistical-based digital matting of natural background is considered in this paper. Performance of the original Bayesian-based matting method has been studied. It is shown that the performance depends on the algorithm initial condition as well as a noise variance parameter. Two initialization methods have been considered. The first one obtains initial value from Ruzon's maximum likelihood method, while the second one employs the centers of foreground and background color clusters as the initial value. Both methods were found to offer improved performance. In addition, optimum choice of the noise variance was found to vary from one image to another. An alternative formulation of a Bayesian-based digital matting technique which does not contain the noise variance parameter is described. It was found to yield results comparable to the original method for most of the test cases. ©2007 IEEE.
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    Fast haptic simulation of brittle object using bounded force propagation model
    (2008-12-01)
    Somrang, Nontapol
    ;
    Chotikakamthorn, Nopporn
    ;
    Jirapatehandej, Siraset
    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. © 2008 IEEE.
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    Weighted hough transform for directional light sources estimation from multi-view images
    (2012-12-01)
    Bunteong, Anusorn
    ;
    Chotikakamthorn, Nopporn
    An improved method for light sources estimation from shading is proposed in this paper. This method indicates the advantage of multi-view images rather than single view image. Even though there are several methods that can be used to estimate light sources from single view image, data from single view may be not accurate for all light source estimations. The shading on a Lambertian surface sphere is used to detection critical paths and the directions of directional light sources can be estimated from these paths. Hough Transform is used to find critical paths from critical points in images. Rather than using the standard Hough Transform, we improve vote count processes by determining a weight value for each critical point in Hough space. Weight values are calculated from angles between surface normal at each critical point and view vector from cameras. The experimental results demonstrate that the proposed method with information obtained from multi-view images yields better performance than the method with a single-view image.
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    Using Mozilla Hubs for Online Teaching: A Case Study of An Innovation Design Method Course
    (2023-01-01)
    Poolsawas, Banyapon
    ;
    Chotikakamthorn, Nopporn
    During the Covid-19 pandemic, video conferencing platforms such as Zoom Online, MS Team Meeting, and Google Meets have been primary remote teaching tools. 3D immersive and non-immersive social platforms such as Mozilla Hubs have been studied as alternative tools for organizing remote teaching. This study aimed to assess the usability of Mozilla Hubs when applied to remote teaching and compared it to that of the widely used Zoom platform. An undergraduate course on innovation design methods was selected as the case study. Students enrolled in this course were divided into two groups. Distance learning was conducted through the Zoom platform for the first group of students. In contrast, the other group participated in the course activities through the Mozilla Hub platform within a non-immersive setting. The students in the Hubs group were requested to participate in the Hub pre-training class a week before the first week of the course's lecture. Six everyday tasks requiring student interaction with each of the two platforms were selected for the study. Usability was measured in terms of efficiency and ease of use. The time taken to complete each of the selected tasks was used to measure the efficiency of each platform. The System Usability Scale (SUS) questionnaire was used to measure ease of use. For most tasks, both platforms yielded comparable results regarding task efficiency. The only exception is for the room transition task, where the results differed between the two platforms depending on whether the teleport or 3D navigation methods were chosen by students in the Hubs group in order to complete the task. Discussion on the factors affecting the efficiency of the room transition task was provided. Using the SUS questionnaire, it was found that both platforms yielded comparable SUS scores of 68.91 and 70.66 for the Zoom and Mozilla Hubs platforms, respectively. Similar ease-of-use results were due to the offering of the Hubs pre-training class to the students using the Mozilla Hubs platform.
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    Evaluation the efficacy of Computer - Based training using tangible user interface for Low-Function children with autism
    (2008-12-01)
    Sitdhisanguan, Karanya
    ;
    Chotikakamthorn, Nopporn
    ;
    Dechaboon, Ajchara
    ;
    Out, Patcharaporn
    Recently, the number of children having autism disorder increases rapidly all over the world. Computerbased training (CBT) has been applied to autism spectrum disorder treatment. Most CBT applications are based on the standard WIMP interface. However, recent study suggests that a Tangible User Interface (TUI) is easier to use for children with autism than the WIMP interface. In this paper, the efficiency of the TUI training system is considered, in comparison with a conventional method of training basic geometric shape classification. A CBT system with TUI was developed using standard computer equipment and a consumer video camera. The experiment was conducted to measure learning efficacy of the new system and the conventional training method. The results show that, under the same time constraint, children with autism who practiced with the new system were able to learn more shapes than those participating in the conventional method. © 2008 IEEE.
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    Comparative study of two projective-invariant digital watermarking methods using cross-ratios and line intersections
    (2005-12-01)
    Pantuwong, Natapon
    ;
    Chotikakamthorn, Nopporn
    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. © 2005 IEEE.
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    Using tangible user interfaces in computer-based training systems for low-functioning autistic children
    (2012-02-01)
    Sitdhisanguan, Karanya
    ;
    Chotikakamthorn, Nopporn
    ;
    Dechaboon, Ajchara
    ;
    Out, Patcharaporn
    In this paper, the design of a computer-based training (CBT) system for low-functioning autistic children is addressed. The emphasis is on ease-of-use and learning efficiency of CBT systems with different interaction styles, namely the WIMP (Window Icon Menu Pointing Device) and TUI (Tangible User Interface) interaction styles. Two WIMP-based CBT systems with different pointing devices were involved in the study. The first system applied a standard computer mouse as a pointing device, while the second one employed a touch screen instead. For the TUI-based CBT system, a tabletop setting was adopted. Based on the known characteristics of TUI and children with autism, as well as related cognitive and learning theories, the benefits of TUI for low-functioning autistic children have been investigated. Elementary skill teaching was chosen as a case study for performance evaluation of these CBT systems. Empirical results show that the touch-based and TUI-based systems offered much better ease-of-use performance than that of the mouse-based system. Regarding learning efficacy, experimental results show that the TUI-based system achieved higher skill improvement, as compared with the WIMP-based system and a non-computer training method. Some guidelines and suggestions for the design of a TUI-based system for children with autism are summarized. © 2011 Springer-Verlag London Limited.
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    Evaluation of mobile phone interaction with large public displays
    (2017-09-05)
    Pattanakimhun, Patchara
    ;
    Chinthammit, Winyu
    ;
    Chotikakamthorn, Nopporn
    Large public displays are widely used in public spaces for serving information. The flow of the information is largely a one-way passive communication due to a lack of user-content interaction, which in some ways limits its effectiveness as an information display system. We propose a use of mobile phones as a tool to interact with a public display. Our proposed mobile-public display user interaction uses a mobile phone to control and retrieve information from a public display. In this paper we present results of a usability test of our proposed interaction, which indicated that there was a strong correlation between the information retrieval performances and the participant's level of engagement with the mobile phone.
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    Electronic document data hiding technique using inter-character space
    (1998-12-01)
    Chotikakamthorn, Nopporn
    In this paper, the problem of hiding data in electronic document for adding captions or fingerprints is considered. A new data hiding scheme, which utilizes difference in character-to-character space for data embedding, is presented. Coding and enhancing techniques are proposed as a means to alleviate effects of noise and distortions, possibly arise during document copying or scanning process. Experimental results using documents written in Thai and English are provided to demonstrate its practical applicability. The method's weakness and future work are also discussed.
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    A light-pointing method for virtual object selection and manipulation in a monoscopic viewing system
    (2005-12-01)
    Kanjanasupark, Pornchai
    ;
    Chotikakamthorn, Nopporn
    Virtual object selection and re-location are two basic object manipulations that can be found in most VR/VE applications. Many interaction metaphors have been developed for object manipulation in VR/VE environments. Of particular interest is the ray-casting method. The method applies a light ray metaphor in selecting and moving a virtual object. However, the method implicitly requires a stereoscopic viewing system to be efficiently use. With a monoscopic viewing system, inefficiency of the method in terms of task completion time is demonstrated in this paper. For a system using a monoscopic viewing device, a light-pointing method based on a laser-pointer metaphor is proposed to alleviate the shortcoming of the original ray-casting method. Compared with the ray-casting method, it was found from the experiment that the proposed method is noticeably more efficient in terms of task completion time. © 2005 IEEE.