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의료영상 분석을 위한 CUDA 기반의 고속 DRR 생성 기법
양상욱(Sangwook Yang),최영(Young Choi),구승범(Seungbum Koo) (사)한국CDE학회 2011 한국CDE학회 논문집 Vol.16 No.4
A pose estimation process from medical images is calculating locations and orientations of objects obtained from Computed Tomography (CT) volume data utilizing X-ray images from two directions. In this process, digitally reconstructed radiograph (DRR) images of spatially transformed objects are generated and compared to X-ray images repeatedly until reasonable transformation matrices of the objects are found. The DRR generation and image comparison take majority of the total time for this pose estimation. In this paper, a fast DRR generation technique based on GPU parallel computing is introduced. A volume ray-casting algorithm is explained with brief vector operations and a parallelization technique of the algorithm using Compute Unified Device Architecture (CUDA) is discussed. This paper also presents the implementation results and time measurements comparing to those from pure-CPU implementation and open source toolkit.
양상욱(Sangwook Yang),최영(Young Choi),구승범(Seungbum Koo) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
A pose estimation process from medical images is calculating locations and orientations of objects obtained from Computed Tomography (CT) volume data utilizing X-ray images from two directions. In this process, digitally reconstructed radiograph (DRR) images of spatially transformed objects are generated and compared to X-ray images repeatedly until reasonable transformation matrices of the objects are found. The DRR generation and image comparison take majority of the total time for this pose estimation. In this paper, a fast DRR generation technique based on GPU parallel computing is introduced. A volume ray-casting algorithm is explained with brief vector operations and a parallelization technique of the algorithm using Compute Unified Device Architecture (CUDA) is discussed. This paper also presents the implementation results and time measurements comparing to those from pure-CPU implementation and open source toolkit.
배열기반 데이터 구조를 이용한 간략한 divide-and-conquer 삼각화 알고리즘
양상욱(Sangwook Yang),최영(Young Choi) (사)한국CDE학회 2009 한국CDE학회 논문집 Vol.14 No.4
Most divide-and-conquer implementations for Delaunay triangulation utilize quad-edge or winged-edge data structure since triangles are frequently deleted and created during the merge process. However, the proposed divide-and-conquer algorithm utilizes the array based data structure that is much simpler than the quad-edge data structure and requires less memory allocation. The proposed algorithm has two important features. Firstly, the information of space partitioning is represented as a permutation vector sequence in a vertices array, thus no additional data is required for the space partitioning. The permutation vector represents adaptively divided regions in two dimensions. The two-dimensional partitioning of the space is more efficient than one-dimensional partitioning in the merge process. Secondly, there is no deletion of edge in merge process and thus no bookkeeping of complex intermediate state for topology change is necessary. The algorithm is described in a compact manner with the proposed data structures and operators so that it can be easily implemented with computational efficiency.
양상욱(Sangwook Yang),정창교(Changkyo Jung),최영(Young Choi),구승범(Seungbum Koo) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
The main purpose of the study is to develop a system to track and analyze the kinematics of small animals using a three-dimensional (3D) model of the animal and multi-view video sequence. Since it is not easy to attach markers to a small animal like an insect and an arthropod, a marker-less motion capture approach is appropriate. The marker-less motion capture includes acquisition of 3D model from the small animal, optimization of the acquisition of multi-view video images, generation of 3D models (visual hull) from the multi-view images for each frame, and calculation of joint kinematics from continuous sequences. As a preliminary research, this paper explains the acquisition process of 3D model from a small animal using 3D laser scanner. The scanning process for a small animal is different from scanning of a solid object, since there are problems coming from the characteristics of the small animals. This paper demonstrates some scanning problems and experimental solutions with examples of scanning tarantula and scorpion.
장치엔치엔(Qianqian Zhang),양상욱(Sangwook Yang),최영(Young Choi) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
In achieving 3D model of blood vessel from computed tomography(CT), it is not easy to separate vascular endothelium and vascular wall since the portion of the blood vessel in a CT volume data is relatively too small and has not sufficient resolution nor distinctive voxel intensity. In case of using vascular contrast agent, detection of the vascular endothelium is feasible but detection of vascular wall is still difficult. This paper proposes a 3D reconstruction process of blood vessel from CT data with intravascular ultrasound(IVUS) data. The shape of vascular endothelium is achieved from CT data by segmentation and then converted to polygonal data with iso-surface extraction. A representative shape of the polygonal data is approximated into a B-spline curve. If a vascular wall shape from an IVUS image is appropriately positioned on the curve at the location of the IVUS image acquisition, the cross-section shape of vascular wall on the location is defined. The 3D surface model of vascular endothelium and vascular walls is constructed from the series of cross-section contours.
정창교(Changkyo Jung),양상욱(Sangwook Yang),최영(Young Choi) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
The purpose of this research is to develop a mesh-based integrated CAD and CAE data representation scheme for the collaboration during the product development process. Since CAE analysis result data of a designed model is generally larger than the model data for CAD visualization, the analysis result cannot be not easily shared on network environment as light-weight data. As a preliminary study of the main research, we introduce an idea for light weight mesh data representation of CAE analysis result data in this paper. The mesh representation involves not only shape representation but also CAE analysis results such as displacements, stresses, and temperatures. The key idea is expanding dimensions of coordinate system of mesh data so that the expanded coordinate systems represent the analysis results as vector or scalar form as well as location in the space. In this paper, we discuss the research background and preliminary idea of the compact CAE mesh representation.