• Title/Summary/Keyword: geometric transformation

Search Result 241, Processing Time 0.03 seconds

A Simple Geometric Approach to Evaluating a Bivariate Normal Orthant Probability

  • Lee, Kee-Won;Kim, Yoon-Tae;Kim, U-Jung
    • Communications for Statistical Applications and Methods
    • /
    • v.6 no.2
    • /
    • pp.595-600
    • /
    • 1999
  • We present a simple geometric approach which uses polar transformation and elementary trigonometry to evaluating an orthant probability in a bivariate normal distribution. Figures are provided to illustrate the situation for varying correlation coefficient. We derive the distribution of the sample correlation coefficient from a bivariate normal distribution when the sample size is 2 as an application.

  • PDF

Study on the development of a personal computer aided 3-D geometric modelling system (PC를 이용한 3차원 입체형상 모델링 시스템 개발 연구)

  • 변문현;오익수
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1988.10a
    • /
    • pp.562-566
    • /
    • 1988
  • The purpose of this study is to develop a personal computer aided 3-D geometric modeller. To perform this study, we set up a cube, a cylinder, and a prism as a primitive in the first segment of this study. By modelling the 3-D object through their transformation, addition, and subtraction, we proved the validity of the developed algorithm and its computer program. Some examples show the results of applying the program to modelling a few simple shape of the machine parts. These results met the first aim of this study.

  • PDF

A Study on the Geometric Correction Accuracy Evaluation of Satellite Images Using Daum Map API (Daum Map API를 이용한 위성영상의 기하보정 정확도 평가)

  • Lee, Seong-Geun;Lee, Ho-Jin;Kim, Tae-Geun;Cho, Gi-Sung
    • Journal of Cadastre & Land InformatiX
    • /
    • v.46 no.2
    • /
    • pp.183-196
    • /
    • 2016
  • Ground control points are needed for precision geometric correction of satellite images, and the coordinates of a high-quality ground control point can be obtained from the GPS measurement. However, considering the GPS measurement requires an excessive amount o f t ime a nd e fforts, there is a need for coming up with an alternative solution to replace it. Therefore, we examined the possibility of replacing the existing GPS measurement with coordinates available at online maps to acquire the coordinates of ground control points. To this end, we examined error amounts between the coordinates of ground control points obtained through Daum Map API, and them compared the accuracies between three types of coordinate transformation equations which were used for geometric correction of satellite images. In addition, we used the coordinate transformation equation with the highest accuracy, the coordinates of ground control point obtained through the GPS measurement and those acquired through D aum M ap A PI, and conducted geometric correction on them to compare their accuracy and evaluate their effectiveness. According to the results, the 3rd order polynomial transformation equation showed the highest accuracy among three types of coordinates transformation equations. In the case of using mid-resolution satellite images such as those taken by Landsat-8, it seems that it is possible to use geometrically corrected images that have been obtained after acquiring the coordinates of ground control points through Daum Map API.

Real-time geometry identification of moving ships by computer vision techniques in bridge area

  • Li, Shunlong;Guo, Yapeng;Xu, Yang;Li, Zhonglong
    • Smart Structures and Systems
    • /
    • v.23 no.4
    • /
    • pp.359-371
    • /
    • 2019
  • As part of a structural health monitoring system, the relative geometric relationship between a ship and bridge has been recognized as important for bridge authorities and ship owners to avoid ship-bridge collision. This study proposes a novel computer vision method for the real-time geometric parameter identification of moving ships based on a single shot multibox detector (SSD) by using transfer learning techniques and monocular vision. The identification framework consists of ship detection (coarse scale) and geometric parameter calculation (fine scale) modules. For the ship detection, the SSD, which is a deep learning algorithm, was employed and fine-tuned by ship image samples downloaded from the Internet to obtain the rectangle regions of interest in the coarse scale. Subsequently, for the geometric parameter calculation, an accurate ship contour is created using morphological operations within the saturation channel in hue, saturation, and value color space. Furthermore, a local coordinate system was constructed using projective geometry transformation to calculate the geometric parameters of ships, such as width, length, height, localization, and velocity. The application of the proposed method to in situ video images, obtained from cameras set on the girder of the Wuhan Yangtze River Bridge above the shipping channel, confirmed the efficiency, accuracy, and effectiveness of the proposed method.

Geocoding of Low Altitude UAV Imagery using Affine Transformation Model (부등각사상변환을 이용한 저고도 UAV 영상의 지형보정)

  • Kim, Seong-Sam;Jung, Jae-Hoon;Kim, Eui-Myoung;Yoo, Hwan-Hee;Sohn, Hong-Gyoo
    • Journal of Korean Society for Geospatial Information Science
    • /
    • v.16 no.4
    • /
    • pp.79-87
    • /
    • 2008
  • There has been a strong demand for low altitude UAV development in rapid mapping not only to acquire high resolution image with much more low cost and weather independent, compared to satellite surveying or traditional aerial surveying, but also to meet many needs of the aerial photogrammetry. Especially, efficient geocoding of UAV imagery is the key issue. Contrary to high UAV potential for civilian applications, the technology development in photogrammetry for example direct georeferencing is in the early stage and it requires further research and additional technical development. In this study, two approaches are supposed for automatic geocoding of UAV still images by simple affine transformation and block adjustment of affine transformation using minimal ground control points and also evaluated the applicability and quality of geometric model compared to geocoded images generated by commercial S/W.

  • PDF

Compensation of Geometric Error by the Correction of Control Surface (제어곡면 수정에 의한 기하오차 보정)

  • Ko, Tae-Jo;Park, Sang-Shin;Kim, Hee-Sool
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.18 no.4
    • /
    • pp.97-103
    • /
    • 2001
  • Accuracy of a machined part is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the relative motion is the geometric errors of a machine tool. In this study, firstly, geometric errors are measured by laser interferometer, and the positioning error of each control point selected uniformly on the control surface CAD model can be estimated from th oirm shaping model and geometric error data base. Where a form shaping function is derived from the link of homogeneous transformation matrix. Secondly, control points are shifted to the estimated amount of positioning errors. A new control surface is modeled with NURBS(Non Uniform Rational B-Spline) surface approximation to the shifted control points. By generating tool paths to the redesigned control surface, we reduce the machining error quite.

  • PDF

A Study on the Abstraction of Learning Materials from the Isoperimetric Problem to Develop a Spatial Sense (등주문제 분석을 통한 공간감각 계발을 위한 학습자료 추출 연구)

  • Choi, Keunbae;Chae, Jeong-Lim
    • School Mathematics
    • /
    • v.16 no.4
    • /
    • pp.677-690
    • /
    • 2014
  • The main goals of learning geometry include developing spatial ability and concepts on geometric objects based on understanding the attributes and relationships of them. While the instructions on geometric objects follow the concept development models, the ones on spatial ability are designed from the perspective of geometric transformation. However, there is a need for instructional materials to emphasizing the relationships among geometric concepts. This study hypothesizes that spatial ability stems from the intuitive understanding of geometric objects and the relational understanding on concepts, and it considers the isoperimetric problems as instructional materials to foster spatial ability.

  • PDF

Selective Encryption Algorithm for Vector Map using Geometric Objects in Frequency Domain

  • Pham, Ngoc-Giao;Kwon, Ki-Ryong;Lee, Suk-Hwan;Woo, Chong-Ho
    • Journal of Korea Multimedia Society
    • /
    • v.20 no.8
    • /
    • pp.1312-1320
    • /
    • 2017
  • Recently, vector map data is developed and used in many domains widely. In the most cases, vector map data contains confidential information which must be kept away from unauthorized users. Moreover, the production process of vector maps is considerably complex and consumes a lot of money and human resources. Therefore, the secured storage and transmission are necessary to prevent the illegal copying and distribution from hacker. This paper presents a selective encryption algorithm using geometric objects in frequency domain for vector map data. In the proposed algorithm, polyline and polygon data in vector map is the target of the selective encryption process. Experimental results verified that proposed algorithm is effectively and adaptive the requirements of security.

Construction of Geometric Learning Contents Using the Experimental Computer Software (탐구형 소프트웨어를 활용한 기하학습내용의 구성방안 탐색)

  • 류희찬;유공주;조민식
    • Journal of Educational Research in Mathematics
    • /
    • v.10 no.1
    • /
    • pp.139-159
    • /
    • 2000
  • The experimental software such as Cabri II, The Geometer's Sketchpad, etc. provides dynamic environment which construct and explore geometric objects interactively and inductively. It has the effects on mathematics itself differently from other technologies that are used in instruction. What is its characteristics\ulcorner What are the educational implication of it for the learning of geometry\ulcorner How is mental reasoning of geometric problems changed by transformation of the means of representation and the environment to manipulate them\ulcorner In this study, we answer these questions through the review of the related literatures and the analysis of textbooks, teaching materials using it and curricular materials. Also, we identify implications about how the criteria for choosing geometic content and the ways of constructing context, for orchestrating the students' exploration with the secondary geometry curriculum, can be changed.

  • PDF

Underwater Acoustic Image Classification of a Cylindrical object using the Hough Transformation and Nth Degree Polynomial Interpolation (N차 다항식 보간법과 허프 변환을 이용한 원통형 수중 물체 영상 식별)

  • Jeong, Euicheol;Shim, Taebo;Kim, Jangeun
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.50 no.2
    • /
    • pp.193-200
    • /
    • 2013
  • In this paper, underwater acoustic image classification of a cylindrical object using the Hough transformation is proposed. Hough transformation is often used to classify a cylindrical object in the optical systems. However, it is difficult to apply to the underwater acoustic image system because of lower resolution and noisier underwater environments. Thus, the cylindrical object was modeled and its geometric depth(GD) pixels were restored in order to make them suitable for the Hough transformation by using moving average filter and a polynomial interpolation method. As a result, restored GD pixels are similar to original ones and test results show high performance in classification.