A Constrained Learning Method based on Ontology of Bayesian Networks for Effective Recognition of Uncertain Scenes

불확실한 장면의 효과적인 인식을 위한 베이지안 네트워크의 온톨로지 기반 제한 학습방법

  • 황금성 (연세대학교 컴퓨터과학과) ;
  • 조성배 (연세대학교 컴퓨터과학과)
  • Published : 2007.06.15

Abstract

Vision-based scene understanding is to infer and interpret the context of a scene based on the evidences by analyzing the images. A probabilistic approach using Bayesian networks is actively researched, which is favorable for modeling and inferencing cause-and-effects. However, it is difficult to gather meaningful evidences sufficiently and design the model by human because the real situations are dynamic and uncertain. In this paper, we propose a learning method of Bayesian network that reduces the computational complexity and enhances the accuracy by searching an efficient BN structure in spite of insufficient evidences and training data. This method represents the domain knowledge as ontology and builds an efficient hierarchical BN structure under constraint rules that come from the ontology. To evaluate the proposed method, we have collected 90 images in nine types of circumstances. The result of experiments indicates that the proposed method shows good performance in the uncertain environment in spite of few evidences and it takes less time to learn.

영상을 분석하여 얻은 증거를 바탕으로 장면의 의미를 추론하고 해석하는 것을 시각 기반 장면 이해라고 하며, 최근 인과적인 판단 및 추론 과정을 모델링하기에 유리한 베이지안 네트워크(BN)를 이용한 확률적인 접근 방법이 활발히 연구되고 있다. 하지만 실제 환경은 변화가 많고 불확실하기 때문에 의미 있는 증거를 충분히 확보하기 어려울 뿐만 아니라 전문가에 의한 설계로 유지하기 어렵다. 본 논문에서는 증거 및 학습 데이타가 부족한 장면인식 문제에서 효율적인BN 구조로 계산 복잡도가 줄어들고 정확도는 향상될 수 있는 BN 학습방법을 제안한다. 이 방법은 추론 대상 환경의 도메인 지식을 온톨로지로 표현하고 이를 제한적으로 사용하여 효율적인 계층구조의 BN을 구성한다. 제안하는 방법의 평가를 위하여 9종류의 환경에서 90장의 영상을 수집하고 레이블링하여 실험하였다. 실험 결과, 제안하는 방법은 증거의 수가 적은 불확실한 환경에서도 좋은 성능을 내고 학습의 복잡도가 줄어듦을 확인할 수 있었다.

Keywords

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