• 디지털콘텐츠학회 논문지
• /
• 제19권1호
• /
• pp.165-171
• /
• 2018

그림자는 자연 영상에서 관찰되는 물리적인 현상으로 지능형 비디오 감시, 교통 감시 및 항공 영상 분석 등과 같은 다양한 영상처리 시스템에 부정적인 영향을 미치는 요소이다. 따라서 그림자의 검출은 컴퓨터 비전의 전 분야에서 전처리 과정으로 고려되어야 한다. 본 논문에서는 참조 영상이 필요 없는 단일 자연 영상에서 그림자 검출을 위한 다양한 특징 요소들을 정의하고 분석하였다. 그림자 요소들은 영상의 밝기, 색도, 조도불변, 색상불변 및 정보의 불확실성을 의미하는 엔트로피 영상 등을 기술하였으며, 분석 결과 색도와 조도불변 영상이 그림자 검출 및 복원에 효과적임을 알 수 있었다. 향후 다양한 그림자 특징 요소들의 퓨전 맵을 정의하고, 다양한 조명 수준에 적응 가능한 그림자 검출 및 색도와 조도불변 영상을 이용한 그림자 제거 연구를 계속하고자 한다.

• 한국ITS학회 논문지
• /
• 제7권1호
• /
• pp.32-41
• /
• 2008

비디오를 이용한 비전기반 감시에서 움직이는 객체의 추적은 GMM (Gaussian Mixture Model)을 사용한 배경영상과 현재영상의 차이법을 이용한다. 문턱치를 통해 생성된 이진영상을 이용하여 객체 추적을 할 경우 객체 정보가 아닌 그림자에 의하여 객체가 병합되는 현상이 나타난다. 본 논문에서는 신경망(Backpropagation Neural Network)을 이용하여 그림자를 제거하는 방법을 제안하였다. 10개의 동영상에서 객체영역과 캐스트그림자(Cast-Shadow)영역의 훈련용 이미지에서 특징 값을 추출하여 신경망을 훈련시켰다. 캐스트그림자를 제거하는 방법은 이진영상의 객체로 추정되는 영역에서 그림자를 분리하는 방법을 기초로 하며 기존의 그림자 제거 알고리즘 (SNP, SP, DNM1, DNM2, CNCC)보다 그림자 제거 성능이 (16.2%, 38.2%, 28.1%, 22.3%, 44.4%)로 높게 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제13권4호
• /
• pp.2042-2059
• /
• 2019

Digital shadow puppet has traditionally relied on expensive motion capture equipments and complex design. In this paper, a low-cost driven technique is presented, that captures human pose estimation data with simple camera from real scenarios, and use them to drive virtual Chinese shadow play in a 2.5D scene. We propose a special method for extracting human pose data for driving virtual Chinese shadow play, which is called 2.5D human pose estimation. Firstly, we use the 3D human pose estimation method to obtain the initial data. In the process of the following transformation, we treat the depth feature as an implicit feature, and map body joints to the range of constraints. We call the obtain pose data as 2.5D pose data. However, the 2.5D pose data can not better control the shadow puppet directly, due to the difference in motion pattern and composition structure between real pose and shadow puppet. To this end, the 2.5D pose data transformation is carried out in the implicit pose mapping space based on self-network and the final 2.5D pose expression data is produced for animating shadow puppets. Experimental results have demonstrated the effectiveness of our new method.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2003년도 춘계학술발표회 논문집
• /
• pp.187-190
• /
• 2003

Due to complexity of diverse features in urban area, accurate feature extraction is laborious task in aerial and satellite imagery. Especially occlusion by buildings, and image distortion of shadow effects make processing more difficult work. In this study, algorithm was presented to correct of shadow effects in aerial color images. This algorithm enables user to accurately interpretate urban information by correction of shadow effects in aerial color images

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2006년도 하계종합학술대회
• /
• pp.303-304
• /
• 2006

This paper proposes detection method of vehicles using camera for auto-vehicle-system. Detection method is based on shadow detection and symmetric feature of vehicle. This method consists of three part. First is lane detection. By lane detection, we can reduce the area for vehicle detection. Second part is shadow detection. Shadow has information of vehicle width and position. Third part is symmetry. This feature is helpful for confirming the vehicle.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
• /
• pp.371-374
• /
• 2008

In very high-spatial resolution remote sensing imagery, it is difficult to extract the feature information of various objects because of occlusion and shadows. Moreover, various and feeble information within shadows can be of use in GIS-based applications and remote sensing analysis. In this paper, we developed a radiometric restoration method for shadow areas using KOMPSAT-2 satellite image. After detecting the shadow, non-shadow pixels nearby are extracted using a morphological filter. An iterative linear regression method is applied to calculate the relationship between shadow and non-shadow pixels. The shadows are restored by the parameters of the linear regression algorithm. Tests show that recovery of shadowed areas by our method leads to improved image quality.

• 한국측량학회:학술대회논문집
• /
• 한국측량학회 2004년도 Korea-Russia Joint Conference on Geometics
• /
• pp.64-72
• /
• 2004

Correction of shadow effects is critical step for image interpretation and feature extraction from aerial imagery. In this paper, an efficient algorithm to correct shadow effects from aerial color imagery is presented. The following steps have been performed to remove the shadow effect. First, the shadow regions are precisely located using the solar position and the height of ground objects derived from LIDAR (Light Detection and Ranging) data. Subsequently, segmentation of context regions is implemented for accurate correction with existing digital map. Next step, to calculate correction factor the comparison between the context region and the same non-shadowed context region is made. Finally, corrected image is generated by correcting the shadow effect. The result presented here helps to accurately extract and interpret geo-spatial information from aerial color imagery

• 한국컴퓨터정보학회논문지
• /
• 제10권1호
• /
• pp.149-156
• /
• 2005

전파를 이용한 통신이 활성화 되어 인터넷상의 네트워크에 연결하여 다양한 서비스가 제공되고 있는 현실에서 통신 서비스의 질을 높이기 위한 물체의 특징 점 탐지 및 추적의 중요성이 크게 대두되었다. 본 논문은 전파가 미치지 않는 음영 공간의 탐지와 추적을 위한 연구의 내용으로, Snakes 알고리즘을 이용하여 음영 공간을 탐지하고, 탐지된 음영 공간 내에서 어느 한 출발 지점에서 목표 지점까지의 경로를 추적하는 시스템의 기반을 제시하고자 하였다.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
• /
• pp.606-609
• /
• 2006

Extraction of building is one of essential issues for the 3D city models generation. In recent years, high-resolution satellite imagery has become widely available, and this shows an opportunity for the urban mapping. In this paper, we have developed a semi-automatic algorithm to extract 3D buildings in urban settlements areas from high-spatial resolution panchromatic imagery. The proposed algorithm determines building height interactively by projecting shadow regions for a given building height onto image space and by adjusting the building height until the shadow region and actual shadow in the image match. Proposed algorithm is tested with IKONOS images over Deajeon city and the algorithm showed promising results.┌阀؀䭏佈䉌ᔀ鳪떭臬隑駭验耀

• 대한원격탐사학회지
• /
• 제23권3호
• /
• pp.211-219
• /
• 2007

Building extraction is one of the essential issues for 3D city modelling. In recent years, high-resolution satellite imagery has become widely available and it brings new methodology for urban mapping. In this paper, we have developed a semi-automatic algorithm to determine building heights from monoscopic high-resolution satellite data. The algorithm is based on the analysis of the projected shadow and actual shadow of a building. Once two roof comer points are measured manually, the algorithm detects (rectangular) roof boundary automatically. Then it estimates a building height automatically by projecting building shadow onto the image for a given building height, counting overlapping pixels between the projected shadow and actual shadow, and finding the height that maximizes the number of overlapping pixels. Once the height and roof boundary are available, the footprint and a 3D wireframe model of a building can be determined. The proposed algorithm is tested with IKONOS images over Deajeon city and the result is compared with the building height determined by stereo analysis. The accuracy of building height extraction is examined using standard error of estimate.