计算机工程

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基于射影几何的CCD 相机几何模型研究

孙 瑜,李占利   

  1. (西安科技大学计算机科学与技术学院,西安710054)
  • 收稿日期:2014-04-30 出版日期:2015-05-15 发布日期:2015-05-15
  • 作者简介:孙 瑜(1982 - ),女,讲师、硕士,主研方向:计算机视觉;李占利,教授、博士。
  • 基金项目:
    陕西省自然科学基金资助项目“基于视觉计算的井下信息感知理论与方法研究”(2012JM8029)。

Research on Geometric Model of CCD Camera Based on Projective Geometry

SUN Yu,LI Zhanli   

  1. (College of Computer Science and Technology,Xi’an University of Science and Technology,Xi’an 710054,China)
  • Received:2014-04-30 Online:2015-05-15 Published:2015-05-15

摘要: 为提高由多幅二维图像解算出的空间坐标信息的精度,基于射影几何原理,提出一种像方空间与物方空间 的几何形状计算方法。分析电荷耦合器件(CCD)相机成像射影几何原理,根据透视变换和交比不变性质,利用直 线之间存在平行、垂直和相交等关系,建立基于直线特征的相机成像几何模型,已知相机参数,证明并推导像方空 间二维影像和物方空间形状与坐标信息的几何转换关系。分析结果表明,该方法结合了整幅图像的几何信息,能 提高空间点等几何特征的坐标信息计算精度,以及视觉测量和三维重建的精度。

关键词: 电荷耦合器件相机, 射影几何, 透视变换, 交比, 成像模型

Abstract: Aiming at enhancing the spatial coordinates precision solved by 2D images, a new method based on projective geometry for calculation of 3D model coordinate transformation between image side and object side space is proposed. Charge Coupled Device ( CCD ) camera imaging geometric principle is analyzed based on perspective transformation and cross-ratio invariant properties. Imaging geometric model based on linear feature is established using the relationship of parallel,perpendicular and intersecting between straight lines. With acquired photographs and camera parameters,the shape and size of the corresponding scene space are deduced and proved on the basis of the cross ratio invariability of collinear points with perspective projection. The coordinate transformation between image side and object side space of the 3D model is calculated. And perspective correspondence from image side to object side space is built. Experimental results prove that the calculation accuracy of the spatial points coordinates can be enhanced by image geometric information. The method can be applied to enhance the precision of image feature extraction and location of geometric features such as circle,and to increase the measurement precisiong of the photogrammetry system and 3D coordinate recnstruction.

Key words: Charge Coupled Device ( CCD ) camera, projective geometry, perspective transformation, cross ratio, imaging model

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