• Journal of the Korea Computer Graphics Society
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• v.23 no.1
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• pp.57-65
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• 2017

In this paper, we present a dictionary learning method for reducing errors in point cloud models and reconstructing their geometry. For this, 3D feature information is extracted from the models which have a similar shape characteristic as the target model. Then a dictionary is constructed and the geometry is reconstructed using the dictionary. The presented method in this paper consists of the following three steps. First, a geometric patch is constructed from a similar model. Second, a morphological 3D feature of the acquired patch is learned. Third, a geometry reconstruction is performed using the learned dictionary. Finally, the error between the original model and the reconstruction result is calculated, and the accuracy of the reconstruction result is checked.

• Journal of the Korea Computer Graphics Society
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• v.20 no.4
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• pp.1-7
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• 2014

The volume rendering has become an important technique in many applications along with hardware development. Understanding and perception of volume visualization benefit from visual cues which are available from shading. Better visual cues can be obtained from global illumination models but it's huge amount of computation and extra GPU memory need cause a lack of interactivity. In this paper, in order to improve visual cues on volume rendering, we propose an image space occlusion shading model which requires no additional resources.

• Journal of the Korea Computer Graphics Society
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• v.23 no.3
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• pp.123-133
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• 2017

Cache performance is an important factor in hardware system. We proceed with a cache simulation to analyze the cache performance suitable for sound rendering. In addition, we introduce hardware models based on ray tracing used in geometric method and studies to improve cache performance. Cache simulation is performed on various conditions for cache size, way and block. Various simulations can be found to influence the cache hit rate. We compare cache simulation results with actual hardware performance to analyze cache performance suitable for sound rendering.

• Journal of the Korea Computer Graphics Society
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• v.21 no.3
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• pp.46-54
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• 2015

Development of digital technology is advancing to levels which influence the formation of city landscapes and spaces. The use of media facade is creating modernized city-spaces with contemporary application of various digital mediums. In this way, media facade functions as media-art in an artistic point of view, while also providing the means for buildings to become landmarks in a city-scape point of view. Going a step further, media facade using interaction is drawing a lot of attention as it enables communication with the city inhabitants instead of one-way contents provision. This paper will research such interactive media facade using transparent display glass currently being used as construction building material and its potential growth.

• Journal of the Korea Computer Graphics Society
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• v.22 no.1
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• pp.1-8
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• 2016

We propose a novel framework for controlling various and complex models using primitive model. To control original model, first we correspond original model to simplified primitive model that contains original model. After doing deformable simulation with primitive model, we compute original model by inversion of result. Since existing method can only control one type formed models, our method - which can control all difference formed models by only one primitive model - has contribution. In conclusion, we show results that efficiently and intuitionally control the various deformable models by using one example primitive model.

• Journal of the Korea Computer Graphics Society
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• v.20 no.3
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• pp.9-17
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• 2014

This paper presents a method to retarget a source motion to the rig-space parameter for a target character that can be equipped with a complex rig structure as used in traditional animation pipelines. Our solution allows the animators to edit the retargeted motion easily and intuitively as they can work with the same rig parameters that have been used for keyframe animation. To acheive this, we analyze the correspondence between the source motion space and the target rig-space, followed by performing non-linear optimization for the motion retargeting to target rig-space. We observed the general workflow practiced by animators and apply this process to the optimization step.

• Journal of the Korea Computer Graphics Society
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• v.24 no.2
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• pp.29-40
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• 2018

Direct volume rendering (DVR) is a commonly used method to visualize inner structures in 3D volumetric datasets. However, conventional volume rendering on a 2D display lacks depth perception due to dimensionality reduction caused by ray casting. In this work, we investigate how emerging Virtual Reality (VR) can improve the usability of direct volume rendering. We developed real-time high-resolution DVR system in virtual reality, and measures the usefulness of volume rendering with improved depth perception via a user study conducted by 38 participants. The result indicates that virtual reality significantly improves the usability of DVR by allowing better depth perception.

• Journal of the Korea Computer Graphics Society
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• v.24 no.4
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• pp.1-9
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• 2018

We propose an emotional training framework that can determine the initial symptom of schizophrenia by using emotional analysis method through facial expression change. We use Emotion API in Microsoft to obtain facial expressions and emotion values at the present time. We analyzed these values and recognized subtle facial expressions that change with time. The emotion states were classified according to the peak analysis-based variance method in order to measure the emotions appearing in facial expressions according to time. The proposed method analyzes the lack of emotional recognition and expressive ability by using characteristics that are different from the emotional state changes classified according to the six basic emotions proposed by Ekman. As a result, the analyzed values are integrated into the image color transfer framework so that users can easily recognize and train their own emotional changes.

• Korean System Dynamics Review
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• v.13 no.2
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• pp.47-71
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• 2012

The purpose of this research is the examination of validity of data as well as simulation model, i.e. to simulate the real data in the SD model with the least error using the adjustments for the faithful reflection of real data to the simulation. In general, SD programs (e.g. VENSIM) utilize the Euler or Runge-Kutta method as an algorithm. It is possible to reflect the trend of real data via these two estimation methods however can cause the validity problem in case of the simulation requiring the accuracy as they have endogenous errors. In this article, the future population estimated by the Korea National Statistical Office (KNSO) to 2050 is simulated by the aging chain model, dividing the population into three cohorts, 0-14, 15-64, 65 and over cohorts by age and offering the adjustments to them. Adjustments are calculated by optimization with three different methods, optimization in EXCEL, manual optimization with iterative calculation, and optimization in VENSIM DSS, the results are compared, and at last the optimal adjustment set with the least error are found among them. The simulation results with the pre-determined optimal adjustment set are validated by methods proposed by Barlas (1996) and other alternative methods. It is concluded that the result of simulation model in this research has no significant difference from the real data and reflects the real trend faithfully.

• Journal of the Korea Computer Graphics Society
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• v.22 no.5
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• pp.49-56
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• 2016

Mobile Virtual Reality Head Mount Displays such as Google Cardboard and Samsung Gear VR are being released, as well as PC-based VR HMDs such as Oculus Rift and HTC Vive. However, when the user wears HMD, it hides the external view of the user. Therefore, it may happen that the user is struck by the surrounding objects such as furniture, and there is no definite solution to this problem. In this paper, we propose a method to reduce the risk of injuries by visualizing the location and information of obstacles scanned by using a RGB-D camera.