Three-dimension locating method based on three-point collineation marker in video frame

A technology of three-dimensional positioning and positioning mark points, which is applied in the field of tracking and positioning technology, can solve the problems of large visual plane, tracking and registration algorithm limitations, etc., and achieve the effect of natural and reasonable experience and flexible shape design

Inactive Publication Date: 2010-05-05
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide an efficient three-dimensional positioning method based on three-point collinear markers, which is used for video images The thr

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  • Three-dimension locating method based on three-point collineation marker in video frame
  • Three-dimension locating method based on three-point collineation marker in video frame
  • Three-dimension locating method based on three-point collineation marker in video frame

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Embodiment Construction

[0015] 以下针对附图和具体实例对本发明的实施进行具体说明。

[0016] attached figure 1 是设置三点共线等距排列的定位标记点示意图。标记点设置应满足以下要求:

[0017] 确保应用过程中摄像机对定位标记点的可见性,即定位标记点在具体应用环境中不会被遮挡;定位标记点的间距视具体应用环境而定,根据实际场景中跟踪目标大小与摄像机的视野确定定位标记点间距,定位标记点的间距与目标大小和摄像机的视野为正比关系,一般目标越大、视野越宽,标记点的间距就越大。通常,对于手持式笔形物体的跟踪,在距离摄像机约50厘米范围内的定位标志点的间距,取7到8厘米比较合适,从而保证笔的长度不超过18厘米;标记点能够较容易地从图像中被提取出来,可采用与背景颜色差异较大的LED亮点作为标记点,也可采用与背景有较大颜色差异的圆形标贴。为方便起见,标记颜色一般选红、绿、蓝三元色中的一种。实例中采用绿色LED亮点。例如简单地,可将3个LED以7厘米的距离等间距地安装在一根平直的塑料棒上,如附 figure 1 shown.

[0018] attached figure 2 是定位标记点对应线段在定位标记坐标系中的位置关系示意图。

[0019] 本实施方案涉及到以下三个坐标系:

[0020] (1)以图像的左上角为原点,水平轴为X轴,垂直轴为Y轴,单位为像素建立图像坐标系,为二维直角坐标系。

[0021] (2)以镜头光心为原点,X轴和Y轴分别与图像坐标系的X轴和Y轴平行,Z轴与图像平面垂直,单位为毫米,建立摄像机坐标系,为三维直角坐标系。

[0022] (3)建立定位标记坐标系,结合附 figure 2 ,设定位标记点所在线段LO的一个端点O为定位标记坐标系的原点,当把定位标记坐标系看成极坐标系时,极轴与摄像机坐标系的X轴平行,LO上的任意一点坐标为 其中l为线段LO上任意一点到原点O的距离, 为线段LO与Z轴的夹角,θ为线段LO到OXY平面的投影与X轴的夹角;当把定位标记坐标系对应为直角坐标系时,X、Y、Z轴分别与摄像机坐标系的X、Y、Z轴平行,LO上的任意一点坐标为[X w , Y w ,Z w ].

[0023] 任一点从极坐标系到直角坐标系的变换式为:

[0024]

[00...

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Abstract

The invention applies to protect a three-dimension locating method based on a three-point collineation marker in a video frame, and relates to the computer vision and image processing technology. The invention, aiming at the defects that the existing track locating algorithm based on plane markers is limited to plane objects and needs larger visual planes, provides a three-dimension locating method based on a three-point collineation marker, which is implemented by obtaining the two-dimensional coordinate information of the locating marker in the video frame, and establishing the relationship between the coordinate of the marker in a locating marker coordinate system and the coordinate of the marker in an image coordinate system to obtain the three-dimension location information and three-dimension posture information of the locating marker in a camera coordinate system. The invention is applied to three-dimension locating of an object having three-point collineation marker in the video frame, and provides a fast and precise tracking method for three-dimension space poin-and-click interactive operation.

Description

technical field [0001] 本发明涉及计算机视觉与图像处理技术,具体是一种对视频帧中特定目标的跟踪定位技术。 Background technique [0002] 增强现实(Augmented Reality)是利用虚拟信息对真实场景进行信息增强的技术。增强现实将用户实际身处的物理环境作为用户的主要感知和交互环境,同时又根据该环境实时生成包括文本、二维图像、三维物体的虚拟信息,通过配准技术将生成的虚拟信息叠加在含有真实场景视频的输出设备上,达到对用户所在的真实场景的解释说明、信息增强或三维展示等目的。 [0003] 文献《Marker Tracking and HMD Calibration for a video-based AugmentedReality Conferencing System》(H.Kato,M.Billinghurst,in Proceedings of the2 nd International Workshop on Augmented Reality,San Francisco,USA,October,1999)中提出了一种基于正方形标志物的用于增强现实的配准算法,并由此开发出一套开源的增强现实软件开发包——ARToolkit。ARToolkit使用计算机视觉技术得到摄像机在标志物坐标系下的位置和姿态信息,实现了对平面物体的跟踪配准,使开发人员能够以该标志物所在平面为基准设定坐标系,进行后续的可视化信息的叠加。其中用于跟踪配准算法的流程为:对视频帧进行二值化处理,寻找具有四个顶点的大面积区域轮廓,提取顶点的图像坐标并与顶点在世界坐标系下的坐标进行对应,得到单应性矩阵(homography),该矩阵反应了真实标志物到图像上的透视变换;结合模板匹配技术,可以得到正确的顶点对应关系,从而实现跟踪配准。 [0004] 由于ARToolkit的跟踪配准算法采用寻找平面标志物轮廓的4个顶点进行对应,局限于平面物体或具有平坦表面物体的跟踪配准,在实际应用过程中需要较大的可视标志物平面,不适合不具备平坦表面的目标跟踪,特别是对于三维空间(或三维虚实融合空间)中类似鼠标、笔等指点式的交互设备的跟踪是不合适的。 Contents of the invention [0005] 本发明所要...

Claims

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Application Information

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IPC IPC(8): G06T7/00
Inventor 康波程序贤
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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