• Title/Summary/Keyword: Landmark

Search Result 601, Processing Time 0.033 seconds

Cephalometric landmark variability among orthodontists and dentomaxillofacial radiologists: a comparative study

  • Durao, Ana Paula Reis;Morosolli, Aline;Pittayapat, Pisha;Bolstad, Napat;Ferreira, Afonso P.;Jacobs, Reinhilde
    • Imaging Science in Dentistry
    • /
    • v.45 no.4
    • /
    • pp.213-220
    • /
    • 2015
  • Purpose: The aim this study was to compare the accuracy of orthodontists and dentomaxillofacial radiologists in identifying 17 commonly used cephalometric landmarks, and to determine the extent of variability associated with each of those landmarks. Materials and Methods: Twenty digital lateral cephalometric radiographs were evaluated by two groups of dental specialists, and 17 cephalometric landmarks were identified. The x and y coordinates of each landmark were recorded. The mean value for each landmark was considered the best estimate and used as the standard. Variation in measurements of the distance between landmarks and measurements of the angles associated with certain landmarks was also assessed by a subset of two observers, and intraobserver and interobserver agreement were evaluated. Results: Intraclass correlation coefficients were excellent for intraobserver agreement, but only good for interobserver agreement. The least reliable landmark for orthodontists was the gnathion (Gn) point (standard deviation [SD], 5.92 mm), while the orbitale (Or) was the least reliable landmark (SD, 4.41 mm) for dentomaxillofacial radiologists. Furthermore, the condylion (Co)-Gn plane was the least consistent (SD, 4.43 mm). Conclusion: We established that some landmarks were not as reproducible as others, both horizontally and vertically. The most consistently identified landmark in both groups was the lower incisor border, while the least reliable points were Co, Gn, Or, and the anterior nasal spine. Overall, a lower level of reproducibility in the identification of cephalometric landmarks was observed among orthodontists.

Robust 3D Facial Landmark Detection Using Angular Partitioned Spin Images (각 분할 스핀 영상을 사용한 3차원 얼굴 특징점 검출 방법)

  • Kim, Dong-Hyun;Choi, Kang-Sun
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.50 no.5
    • /
    • pp.199-207
    • /
    • 2013
  • Spin images representing efficiently surface features of 3D mesh models have been used to detect facial landmark points. However, at a certain point, different normal direction can lead to quite different spin images. Moreover, since 3D points are projected to the 2D (${\alpha}-{\beta}$) space during spin image generation, surface features cannot be described clearly. In this paper, we present a method to detect 3D facial landmark using improved spin images by partitioning the search area with respect to angle. By generating sub-spin images for angular partitioned 3D spaces, more unique features describing corresponding surfaces can be obtained, and improve the performance of landmark detection. In order to generate spin images robust to inaccurate surface normal direction, we utilize on averaging surface normal with its neighboring normal vectors. The experimental results show that the proposed method increases the accuracy in landmark detection by about 34% over a conventional method.

A Landmark Based Localization System using a Kinect Sensor (키넥트 센서를 이용한 인공표식 기반의 위치결정 시스템)

  • Park, Kwiwoo;Chae, JeongGeun;Moon, Sang-Ho;Park, Chansik
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.63 no.1
    • /
    • pp.99-107
    • /
    • 2014
  • In this paper, a landmark based localization system using a Kinect sensor is proposed and evaluated with the implemented system for precise and autonomous navigation of low cost robots. The proposed localization method finds the positions of landmark on the image plane and the depth value using color and depth images. The coordinates transforms are defined using the depth value. Using coordinate transformation, the position in the image plane is transformed to the position in the body frame. The ranges between the landmarks and the Kinect sensor are the norm of the landmark positions in body frame. The Kinect sensor position is computed using the tri-lateral whose inputs are the ranges and the known landmark positions. In addition, a new matching method using the pin hole model is proposed to reduce the mismatch between depth and color images. Furthermore, a height error compensation method using the relationship between the body frame and real world coordinates is proposed to reduce the effect of wrong leveling. The error analysis are also given to find out the effect of focal length, principal point and depth value to the range. The experiments using 2D bar code with the implemented system show that the position with less than 3cm error is obtained in enclosed space($3,500mm{\times}3,000mm{\times}2,500mm$).

A Study on Perception Differences between Local Residents and Tourists Regarding Regional Landmark Cognitive Factors (지역 랜드마크 인지요인에 대한 지역주민과 관광객의 인식차이에 관한 연구)

  • Choi, Dong-Heui
    • Journal of Digital Convergence
    • /
    • v.17 no.11
    • /
    • pp.53-59
    • /
    • 2019
  • The purpose of this study is to verify what effects regional landmark cognitive factors have on tourist satisfaction and how the effect relationship between regional landmark cognitive factors and tourist satisfaction change due to perception differences between local residents and tourists and to present implications. Analysis results show that landmark cognitive factors could be categorized into the single factors of symbolism, historicity, and tourist satisfaction. Landmark cognitive factors had significant effects on tourist satisfaction and differences occurred in that effect relationship according to local residents and tourists. Therefore, when tourism products are developed through landmarks, if the opinions of local residents are excessively reflected, this can bring about outcomes that actually disregard tourists, so it is important to appropriately reflect various opinions.

Accuracy of Automatic Cephalometric Analysis Programs on Lateral Cephalograms of Preadolescent Children (소아 환자 대상의 자동 계측점 식별 프로그램의 정확성 평가)

  • Song, Min Sun;Kim, Seong-Oh;Kim, Ik-Hwan;Kang, Chung-min;Song, Je Seon
    • Journal of the korean academy of Pediatric Dentistry
    • /
    • v.48 no.3
    • /
    • pp.245-254
    • /
    • 2021
  • The aim of this study was to evaluate the accuracy of 3 different automatic landmark identification programs on lateral cephalgrams and the clinical acceptability in pediatric dentistry. Sixty digital cephalometric radiographs of 7 to 12 years old healthy children were randomly selected. Fourteen landmarks were chosen for assessment and the mean of 3 measurements of each landmark by a single examiner was defined as the baseline landmarks. The mean difference between an automatically identified landmark and the baseline landmark was measured for each landmark on each image. The total mean difference of 3 automatic programs compared to the baseline landmarks were 2.53 ± 1.63 mm. Errors among 3 programs were not significantly different for 12 of 14 landmarks except Orbitale and Gonion. The automatic landmark identification programs showed significant higher mean detection errors than the manual method. The programs couldn't be used as the 1st tool to replace human examiners. But considering short consuming time, these results indicate that all 3 programs have sufficient validity to be used in pediatric dental clinic.

A Study of Fitness Evaluation System for Knit Bodice Pattern (니트 상의 패턴의 맞음새 평가방법 연구)

  • 천종숙;허지혜
    • Journal of the Korean Society of Clothing and Textiles
    • /
    • v.22 no.4
    • /
    • pp.482-492
    • /
    • 1998
  • With the purpose of developing a objective fitness evaluation system for knits, the basic bodice pattern for knit was drafted and the suitability of the altered pattern was evaluated. For each of nine different knits, six sleeveless shirts were made with patterns that were altered by different pattern alteration rate: 0%, 30%, 40%, 50%, 60%, or 70% of the stretch rate of the knit. The panel that was composed of 25 clothing specialists evaluated the fitness of the garments. The distance from the dress form landmark to the garment landmark was measured from each experimental garment. And the results of garment fitness evaluation and the measurement of distance from the dress form landmark to garment landmark were compared. The results of this study are as follows: There was high correlation(r$\geq$0.9) between the evaluation of the panel about the garment fit and the landmarks distance. The stretch rate of knits affected the evaluation of the garment fit. The stretch rate in course of knits affected on the garment fit at crosswise direction. The suitable pattern alteration rate was lower than 30% for the knits with high stretch rate in course. It was concluded that in order to get the appropriate knit bodice pattern length, the front bodice pattern must be less shorten than the back bodice pattern. The alteration rate at hip line must be lower than for waist or bust line.

  • PDF

Extraction of Landmarks for Pedestrian Navigation System (보행자 내비게이션 시스템을 위한 랜드마크 추출 방법)

  • Rho, Gon-Il;Kim, Ji-Young;Yu, Ki-Yun
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.29 no.4
    • /
    • pp.413-420
    • /
    • 2011
  • This study is to extract landmark buildings for pedestrian navigation from the existing spatial data sets automatically. At first, we defined candidates for landmark based on sight of pedestrian, then extracted final landmark by evaluating attributes of each candidate. The attribute is evaluated with relative or absolute criteria depending on the nature of each attribute. Landmarks extracted through the proposed method are compared to existing landmarks for vehicle and assessment of the validity and the applicability is performed. As a result, extracted Landmarks are expected to help guiding pedestrian effectively.

A Study of the Construction and Application of Point of Interest Data for Search and Guide (생활지리정보 검색 및 안내를 위한 POI의 구축 및 활용)

  • Kim, Dae-Sik;Kim, Hyung-Jin;Son, Bong-Soo;Yu, Wann
    • Proceedings of the Korea Contents Association Conference
    • /
    • 2003.11a
    • /
    • pp.423-430
    • /
    • 2003
  • Generally, elements of DRM(Digital Road Map) consist of road, background and landmark data. The landmark, expressed as text and symbol, on map and additional search data are processed by GISSD(Geo-spatial Information System Service Data). This paper aims to develop the DBMS(Database Management System) for operating landmark and search data, and to discuss the characteristics and application of the DBMS. To accomplish the two objectives, the following four tasks were performed in this study. First, the working scopes of field survey and specification to construct the GISSD were defined. Second, the suggested process of manufacture and design of database were described. Third, the software for required construction and management of the system were developed. Lastly, the properties of developed system and data were analyzed. Especially, the efforts for the GISSD in this study are expected to provide a direct use and practical application to the creation of landmark in DRM and search data.

  • PDF

A Study on the Landmark Experience for Anchorage in Pusan port (부산항에 있어서 묘박을 위한 랜드마크 체험에 관한 연구)

  • 이동화;강영조
    • Journal of the Korean Institute of Landscape Architecture
    • /
    • v.27 no.4
    • /
    • pp.59-64
    • /
    • 1999
  • This study is about gaining orientation through anchorage act of a group of ferryman. In addition, a point acquisition and character of landmark that is closely realated to a point acquisition would be clarified by studying the form of configuration of the earth and object which is used landmark for anchorage. There are 13 anchorage points in the north part of Pusan harbor. 12 anchorage points are used to anchor. A ferryman let a ship which is temporarily anchoring move safely and speedily at the anchorage point. At that time, he uses landmarks by a technique of Overlay View. Between landmarks and viewer would be formed exquisite location combination. A mountain peak, a peak of island, nature configuration of land such as intermitent rock and location, size and form of buildings or structures of a city were variously appeared as landscape elements which were used landmarks. Looking at conditions to be easily captured as a target object, 1. A particular point of a mountain ridge line which was not shield by buildings. 2. In case objects have similar form, the building which was located in the front or the highest. 3. In case of a singular object, whatever there is physical elements, that would be a target object. Through this study a configuration of the ground such as a mountain peak which is become the background of harbor landscape is very important element to find anchorage point in configuration of the ground and object. So, the continuous preservation of the contour line of mountain is needed to do safe and effective anchorage act.

  • PDF

A Study on Designing Metadata Standard for Building AI Training Dataset of Landmark Images (랜드마크 이미지 AI 학습용 데이터 구축을 위한 메타데이터 표준 설계 방안 연구)

  • Kim, Jinmook
    • Journal of the Korean Society for Library and Information Science
    • /
    • v.54 no.2
    • /
    • pp.419-434
    • /
    • 2020
  • The purpose of the study is to design and propose metadata standard for building AI training dataset of landmark images. In order to achieve the purpose, we first examined and analyzed the state of art of the types of image retrieval systems and their indexing methods, comprehensively. We then investigated open training dataset and machine learning tools for image object recognition. Sequentially, we selected metadata elements optimized for the AI training dataset of landmark images and defined the input data for each element. We then concluded the study with implications and suggestions for the development of application services using the results of the study.