• Title, Summary, Keyword: LOD

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LOD management for u-GIS 3D models (u-GIS 3D 모델의 LOD 관리 프로그램)

  • Choi, Jin-Woo;Yang, Young-Kyu
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.148-151
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    • 2009
  • u-GIS 공간정보를 제공하기 위한 3D 모델의 렌더링 성능을 향상시키기 위해 일반적으로 Discrete LOD 기법이 적용된다. 하지만 u-GIS의 3D 건물 모델은 그 복잡성이 매우 높아 LOD 단계별로 모델을 직접 생성하려면 많은 비용과 시간이 소요되어 효율적이지 못하다. 본 연구에서는 원본 3D 모델을 활용하여 하위 LOD 단계의 모델을 메쉬 간략화 알고리즘인 QEM 기법을 통해 생성하는 프로그램을 구현하였다. 프로그램은 다양한 3D 모델의 데이터 포맷을 입력받고 출력할 수 있도록 하여 범용성을 높이고, 생성되는 모델의 결과를 바로 화면으로 확인할 수 있도록 하여 사용자 편의성을 확보하였다. 몇 개의 실제 3D 건물 모델로 실험을 수행하여 프로그램의 성능을 검증하고 그 결과를 도출하였다.

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LOD Representation for the Realtime Simulation of Flocking Objects (군집행동개체의 실시간 애니메이션을 위한 단계별 상세화 표현)

  • Cho S.H.;Chai Y.H.
    • Korean Journal of Computational Design and Engineering
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    • v.10 no.5
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    • pp.339-348
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    • 2005
  • In this paper, LOD (Level Of Detail) for flocking, which is the real-time simulation on the movement or some groups such as fighting soldiers, moving fishes and flying birds, is presented. And a flocking LOD algorithm that uses factors such as the speed of fish, direction, and shape is proposed. Model data is modified for LOD in advance, so as to reduce strange edge collapse and unwanted holes. The errors of model data were identified by transforming polygonal model into octree-based cubes and revised before rendering. Experimental results show that the proposed algorithm considering flocking characteristics shows fast frame rates as compared with the conventional continuous LOD algorithm.

LOD Application for Linking Bridge Information Model into GIS (교량정보모델과 GIS의 연계를 위한 LOD 적용 방안)

  • An, Hyun-Jung;Park, Sang-Il;Kim, Hyo-Jin;Lee, Sang-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.356-359
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    • 2009
  • 본 연구에서는 교량의 정보를 효율적으로 관리하고 활용할 수 있는 3차원 형상기반 표준정보모델을, 현실 세계와 유사한 3차원 가상공간에 표현함으로써 실제 공간에 대해 보다 정확한 분석을 수행 할 수 있도록 교량정보모델과 3차원 지리정보체계를 연계하는 방안을 제시하였다. 교량의 표준정보모델은 기존에 개발된 STEP 기반의 교량정보모델을 활용하였으며, 3차원 지리정보체계는 지리정보상에 3차원 도시객체를 표현하기 위한 표준데이터모델인 CityGML를 활용하였다. 교량정보모델을 GIS와 연계하기 위한 핵심 요소인 교량구조물의 형상표현 LOD(Level of Detail)는 CityGML의 가이드라인을 준용하여 교량구조물에 적합하도록 새롭게 구성하였다. 즉, 빌딩구조물 위주로 정의되어진 기존의 CityGML의 한계점을 극복하기 위해, 총 5단계의 교량구조물의 LOD를 작성하여 각 단계별로 지리정보 상에 교량 형상을 표현할 수 있도록 LOD를 정의하였다. 또한, 두 모델을 소프트웨어적으로 연계하기 위하여 기존의 STEP 기반 교량정보모델을 활용하여, GIS의 정보로 변환하기 위한 소프트웨어 아키텍처를 구성하였다.

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A Study on Regular Grid Based Real-Time Terrain LOD Algorithm for Enhancing Memory Efficiency (메모리 효율 향상을 위한 고정격자기반 실시간 지형 LOD 알고리즘에 관한 연구)

  • Whangbo Taeg-keun;Yang Young-Kyu;Moon Min-Soo
    • Korean Journal of Remote Sensing
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    • v.20 no.6
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    • pp.409-418
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    • 2004
  • LOD is a widely used technique in 3D game and animation to represent large 3D data sets smoothly in real-time. Most LOD algorithms use a binary tree to keep the ancestor information. A new algorithm proposed in this paper, however, do not keep the ancestor information, thus use the less memory space and rather increase the rendering performance. To verify the efficiency of the proposed algorithm, performance comparison with ROAM is conducted in real-time 3D terrain navigation. Result shows that the proposed algorithm uses about 1/4 of the memory space of ROAM and about 4 times faster than ROAM.

Implementation of Policy based In-depth Searching for Identical Entities and Cleansing System in LOD Cloud (LOD 클라우드에서의 연결정책 기반 동일개체 심층검색 및 정제 시스템 구현)

  • Kim, Kwangmin;Sohn, Yonglak
    • Journal of Internet Computing and Services
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    • v.19 no.3
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    • pp.67-77
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    • 2018
  • This paper suggests that LOD establishes its own link policy and publishes it to LOD cloud to provide identity among entities in different LODs. For specifying the link policy, we proposed vocabulary set founded on RDF model as well. We implemented Policy based In-depth Searching and Cleansing(PISC for short) system that proceeds in-depth searching across LODs by referencing the link policies. PISC has been published on Github. LODs have participated voluntarily to LOD cloud so that degree of the entity identity needs to be evaluated. PISC, therefore, evaluates the identities and cleanses the searched entities to confine them to that exceed user's criterion of entity identity level. As for searching results, PISC provides entity's detailed contents which have been collected from diverse LODs and ontology customized to the content. Simulation of PISC has been performed on DBpedia's 5 LODs. We found that similarity of 0.9 of source and target RDF triples' objects provided appropriate expansion ratio and inclusion ratio of searching result. For sufficient identity of searched entities, 3 or more target LODs are required to be specified in link policy.

A Study on Feasible 3D Object Model Generation Plan Based on Utilization, Demand, and Generation Cost (입체모형 활용 현황, 수요 및 구축 비용을 고려한 실현 가능한 3차원 입체모형 구축 방안 연구)

  • Kim, Min-Soo;Park, Doo-Youl
    • Journal of Cadastre & Land InformatiX
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    • v.50 no.1
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    • pp.215-229
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    • 2020
  • In response to the recent 4th industrial revolution, the demand for 3D object models in the latest fields of digital twin, autonomous driving, and VR/AR, as well as the existing fields such as city, construction, transportation, and energy has increased significantly. It is expected that the demand for 3D object models with various precision from LOD1 to LOD4 will increase more and more in various industry fields. However, the Ministry of Land, Infrastructure and Transport, and the local government and the private sector have partially built 3D object models of different precisions for some specific regions because of the huge cost. Therefore, this study proposes a feasible plan that can solve the cost problem in generating 3D object models for the whole territory. For our purpose, we first analyzed usage, demand, generation technology and generation cost for 3D object models. Afterwards, we proposed LOD3 model generation plan for all territory using automatic 3D object model generation technology based on image matching. Additionally, we supplemented the proposed plan by using LOD4 generation plan for landmarks and LOD2 generation plan non-urban area. In the near future, we expect this would be a great help in establishing a feasible and effective 3D object model generation plan for the whole country.

Wavelet-Based Level-of-Detail Representation of 3D Objects (웨이브릿 기반의 3차원 물체 LOD 표현)

  • Lee, Ha-Sup;Yang, Hyun-Seung
    • Journal of KIISE:Computer Systems and Theory
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    • v.29 no.4
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    • pp.185-191
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    • 2002
  • In this paper, we propose a 3D object LOD(Level of Detail) modeling system that constructs a mesh from range images and generates the mesh of various LOD using the wavelet transform. In the initial mesh generation, we use the marching cube algorithm. We modify the original algorithm to apply it to construct the mesh from multiple range images efficiently. To get the base mesh we use the decimation algorithm which simplifies a mesh with preserving the topology Finally, when reconstructing new mesh which is similar to initial mesh we calculate the wavelet coefficients by using the wavelet transform. We solve the critical problem of wavelet-based methods - the surface crease problem (1) - by using the mesh simplification as the base mesh generation method.

Efficient Data Structures and Algorithms for Terrain Data Visualization (지형 렌더링을 위한 효율적인 자료 구조와 알고리즘)

  • Jung, Moon-Ju;Han, Jung-Hyun
    • The KIPS Transactions:PartA
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    • v.9A no.4
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    • pp.581-588
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    • 2002
  • In implementing interactive multimedia systems, real-time visualization plays an important role. This paper presents efficient data structures and algorithms for real-time terrain navigation. Terrain data set is usually too huge to display as is. Therefore LOD (levels of detail) methods and view frustum culling are essential tools. This paper describes in detail compact hierarchical data structures, fast view frustum culling, and efficient LOD construction/rendering algorithms. Unlike previous works, we use a precise screen-space error metric for vertex removal and a strict error threshold allowing sub-pixel -sized errors only. Nevertheless, we can achieve 22 fps on average in a PC platform. The methods presented in this paper also satisfy almost all of the requirements for interactive real-time terrain Visualization.

Level Scale Interface Design for Real-Time Visualizing Large-Scale Data (대용량 자료 실시간 시각화를 위한 레벨 수준 표현 인터페이스 설계)

  • Lee, Do-Hoon
    • Journal of the Korea Society of Computer and Information
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    • v.13 no.2
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    • pp.105-111
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    • 2008
  • Various visualizing methods have been proposed according to the input and output types. To show complex and large-scale raw data and information. LOD and special region scale method have been used for them. In this paper, I propose level scale interface for dynamic and interactive controlling large scale data such as bio-data. The method has not only advantage of LOD and special region scale but also dynamic and real-time processing. In addition, the method supports elaborate control from large scale to small one for visualization on a region in detail. Proposed method was adopted for genome relationship visualization tool and showed reasonable control method.

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A Study on the Weight Lightening Algorithm of 3-Dimensional Large Object based on Spatial Data LOD (공간데이터 LOD 기반 3차원 대용량 객체의 경량화 알고리즘 연구)

  • Na, Joon Yeop;Hong, Chang Hee
    • Spatial Information Research
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    • v.21 no.6
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    • pp.1-9
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    • 2013
  • Recently, Construction information is being changed from CAD to BIM, and GIS is extending from outdoor to indoor information. In these circumstances, the needs of continuous use of construction information linked with GIS are growing constantly in stages of maintenance, operation and service as well as planning, design and construction. To this end, it is essential element to represent 3-dimensional large object efficiently in establishing BIM-GIS interoperability platform by combination of construction and spatial information. In this study, we design spatial data LOD for making spatial object and texture by level, and develop weight lightening algorithm of large spatial object.