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이주행(Joo-Haeng Lee) (사)한국CDE학회 2012 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2012 No.2
When applying a spatial augmented reality (SAR) technique using a projector, we need to solve an inverse projection problem. In a forward projection, we compute the projected image on a given surface from a projector with known internal and external parameters, which is a straightforward process using a projective geometry. In an inverse projection, however, we need to find internal and external parameters of an unknown projector that can project a given target image. Usually, we need to pre-warp a source image. In this paper, we investigate both geometric and analytic meaning of this problem and give partial solution in two different ways when a given target image is a convex quadrilateral. In a geometric sense, we show that the solution exists within a circle defined by two diagonals of a given quadrilateral. In an analytic sense, we propose a simple equation that can be used to determine projectability of a given quadrilateral.
이주행(Joo-Haeng Lee),김현(Hyun Kim),서영호(Youngho Suh),조준면(Junmyun Cho) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
로보틱 SAR (Robotic SAR, RSAR) 기술은 초소형 프로젝터와 카메라로 구성된 공간증강현실 (SAR, spatial augmented reality) 기술에 로보틱스 기술을 접목하여, 실제 사물을 인식하고, 물체 표면이나 주변에 상황에 맞는 정보 및 사용자 인터페이스를 투사방식으로 증강하는 기술이다. 제어 측면에서는 프로젝터-카메라 모듈의 위치와 방위를 기구학적으로 결정해야 하며, 그와 동시에 컴퓨터 그래픽스 및 컴퓨터 비젼 기술을 이용하여 사물의 표면을 인식하고 그에 맞게 투사될 영상을 생성해야 한다. 이 기술은 모바일 증강현실이나 모바일/고정형 공간증강현실 기술에 비해 실제 사물과 가상의 정보가 효과적으로 결합되어 사용자 상호작용 측면에서 다양한 장점을 갖는 반면에, 사물과 사물의 충돌 회피와 더불어 투사되는 빛과 사물의 상호작용을 동시에 다루어야 한다는 점에서 기존의 로보틱스의 역운동학 제어와는 다른 문제들을 갖게 된다. 본 논문은 현재 실험중인 로보틱 SAR 시스템에서 발생하는 이러한 문제들을 정리하고 이를 해결하기 위한 기본적인 접근 방향을 제시한다.
이주행(Joo-Haeng Lee),김현(Hyun Kim),서영호(Youngho Suh),김형선(Hyungsun Kim) (사)한국CDE학회 2011 한국CDE학회 논문집 Vol.16 No.6
A robotic spatial augmented reality (RSAR) system combines a robotics technology with a spatial augmented reality system (SAR) where cameras are used to recognize real objects and projectors augment information and user interface directly on the surface of the recognized objects, rather than relying on handheld display devices. Moreover, a robotic module is actively used to discover and utilize the context of users and environments. The control of a RSAR system involves several issues from different technical fields such as classical inverse kinematics of motors where projector-camera pairs are mounted, inverse projection problems to find appropriate internal/external parameters of projectors and cameras, and image warping in graphics pipeline to compensate the kinematic constraints. In this paper, we investigate various control issues related to a RSAR system and propose basic approaches to handle them, specially focused on the prototype RSAR system developed in ETRI.
사각형 복원을 위한 새로운 기하학적 도구로서의 선분 카메라 쌍
이주행(Joo-Haeng Lee) (사)한국CDE학회 2015 한국CDE학회 논문집 Vol.21 No.2
We review recent research results on coupled line cameras (CLC) as a new geometric tool to reconstruct a scene quadrilateral from image quadrilaterals. Coupled line cameras were first developed as a camera calibration tool based on geometric insight on the perspective projection of a scene rectangle to an image plane. Since CLC comprehensively describes the relevant projective structure in a single image with a set of simple algebraic equations, it is also useful as a geometric reconstruction tool, which is an important topic in 3D computer vision. In this paper we first introduce fundamentals of CLC with reals examples. Then, we cover the related works to optimize the initial solution, to extend for the general quadrilaterals, and to apply for cuboidal reconstruction.
Joo-Haeng Lee(이주행),Jae Yeol Lee(이재열),Hyun Kim(김현),Hyoung-Sun Kim(김형선) 한국산업경영시스템학회 2002 한국산업경영시스템학회 학술대회 Vol.2002 No.추계
Geometric shape morphing is a special geometric operation that interpolates two geometric shapes to generate in-between shapes, which can be used in various design applications such as pipe-like surface design or motion simulation in CAD/CAM. It has been well known that Minkowski sum can be used to design collision-free motion path and to modify geometric shapes. Recently, we developed a geometric modeling technique to interactively control geometric shape morphing based on Minkowski sum. The basic idea develops from the linear interpolation on two geometric shapes where the traditional algebraic sum is replaced by Minkowski sum. We extended this scheme into n-th degree B?zier and blossom control with multiple control shapes. In this paper, we introduce mathematical models of the proposed control structure and some of their properties. Moreover, we present a fast and efficient computation method based on direction map analysis, which has been optimized for repeated generation of in-betweens to outperform previous algorithms.
사각형 복원을 위한 새로운 기하학적 도구로서의 선분 카메라 쌍
이주행(Joo-Haeng Lee),이아현(Ahyun Lee) (사)한국CDE학회 2015 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2015 No.동계
We review recent research results on coupled line cameras (CLC) as a new geometric tool to reconstruct a scene quadrilateral from image quadrilaterals. Coupled line cameras were first developed as a camera calibration tool based on geometric insight on the perspective projection of a scene rectangle to an image plane. Since CLC comprehensively describes the relevant projective structure in a single image with a set of simple algebraic equations, it is also useful as a geometric reconstruction tool, which is an important topic in 3D computer vision. In this paper we first introduce fundamentals of CLC with reals examples. Then, we cover the related works to optimize the initial solution, to extend for the general quadrilaterals, and to apply for cuboidal reconstruction.