Chotikakamthorn, Nopporn

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

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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 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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    Interactive public display using mobile web client
    (2017-07-01)
    Pattanakimhun, Patchara
    ;
    Chotikakamthorn, Nopporn
    ;
    Chinthammit, Winyu
    Large public displays are widely used in public spaces for serving information. Most of them lack user-content interaction due partly to the fact that a touch screen is not suitable. With nearly universal adoption of mobile smartphone devices worldwide, its use as a tool for interacting with a public display is a viable option. Lack of standard interaction methods, protocols, and wide-spread used mobile applications for this purpose is a problem that prevents its adoption. In this paper, we address these problems by proposing a method with a mobile phone device as a tool for interaction with a public display system. The method is based on a standard web client, preinstalled on all smartphone devices, thus avoiding the problem as mentioned. Standard mobile gestures were employed for ease of use. The problem of establishing a connection and getting control of the public display is addressed. Three pairing methods have been described and evaluated. The results and discussion are provided.
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    Handwriting rearrangement for Thai calligraphy
    (2017-02-23)
    Tonmaithong, Karun
    ;
    Annanab, Supawan
    ;
    Chotikakamthorn, Nopporn
    In this paper we propose a new algorithm to rearrange handwriting for Thai online handwriting beautification. First, we segment the line into the right group (Line of tone level, Line of upper level, Line of body level and Line of lower level). Then we calculate the center point of each character by x average and y average value. After that we find the moving path that includes two perpendicular marks at the end of the path. Finally, we adjust Thai handwriting by moving the character up or down along the Moving line. The text's position is changed into the middle point of the Moving line.
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    Near point light source location estimation from shadow edge correspondence
    (2015-09-23)
    Chotikakamthorn, Nopporn
    The problem of near point light source location estimation is considered. The approach described here is based on a relationship between the cast shadow edge, the shadow-casting surface, and the light source. Given an optical-depth image pair available from an RGB-D camera, a method for near point light source location estimation is described. The method can be applied to a shadow-casting object with arbitrary and unknown geometry. Exhaustive multidimensional search is avoided by the proposed iterative one-dimensional search algorithm. Experimental results with real images are included.
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    An efficient P2P searching and indexing strategy for multi-keyword query
    (2013-01-01)
    Jitnupong, Tanapon
    ;
    Chotikakamthorn, Nopporn
    Multi-keyword search in a P2P repository system based on DHT suffers from high traffic cost due to intersection operation of distributed inverted lists. Indexing by a set of keywords (term set) is one possible solution to reduce the cost. However, as the number of terms for each set increases, the number of possible term sets increases tremendously. Index pruning partly solves the problem, with the cost of reduced recall rate. In this paper, a multi-keyword search strategy for use with the term-set index pruning technique is proposed to increase recall rate, while retaining the same index size required for the case of a two-keyword search. Experimental result supports the predicted improvement.
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    Query decomposition method for multi-keyword search in P2P systems
    (2015-01-01)
    Chotikakamthorn, N.
    ;
    Jitnupong, T.
    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 multiterm 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.
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    Blockchain-based Learning Credential Verification System with Recipient Privacy Control
    (2019-12-01)
    San, Aye Mi
    ;
    Chotikakamthorn, Nopporn
    ;
    Sathitwiriyawong, Chanboon
    Various forms of learning credentials play an important role in society. For example, a degree certificate is usually required to apply for many jobs. Currently, paper-based learning credentials such as diploma or degree certificates are still widely used. However, proof of such credentials' authenticity has become increasingly more difficult in recently years due to availability of low-cost desktop publishing tools. Recently, a blockchain-based digital certificate issuing and verification system has been proposed to address these problems. However, existing blockchain-based certification verification solutions have a few shortcomings in common. One of them is the lack of mechanism to control the amount of information and anonymity exposed during the verification process. This paper proposed a blockchain-based learning credential verification system, where a} {credential recipient can control the amount of credential-related information to be exposed during the verification process. The proposed solution makes use of a Merkle tree to encode causal relationship among pieces of information the credential is composed of. The abstract data model built on top of the binary Merkle tree has been proposed so that a recipient can choose to disclose part of the credential information, including the recipient profile. This means it is possible for credential verification to be performed anonymously. This can be achieved without increasing blockchain transaction cost and complexity. Example of use case scenarios that require such anonymous verification are described.
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    Near light source location estimation using illumination of a diffused planar background
    (2014-11-10)
    Chotikakamthorn, Nopporn
    The problem of light source location estimation is considered. It is shown that the location of a near light source can be estimated from an optical-depth image pair using information available from an illuminated Lambertian planar background. The method estimates the projected source location on the planar background from the surface illumination gradient. The distance of the light source from the planar background, which is equivalent to its elevation angle, is estimated by fitting the radiance of the background surface as observed by an optical image, with those synthesized at different light distances. The fitting equation is formulated such that the possible existence of environment light can be taken into account. Experimental results with real images are provided.