三维PIV透视成像粒子定位的可确定性

三维粒子成像测速 (PIV)的透视成像分析方法中 ,在运用体积光照明并从多个不同光轴方向用多台照相机或摄像机同时获得PIV图像后 ,根据多幅不同光轴的PIV图像的透视性质 ,运用物点三维定位的透视成像定位原理和方法 ,可通过找出各透视面上像点所对应的透视射线的交点来确定相应粒子的三维位置。问题在于 ,尽管粒子所在位置上必然存在各像点相应的透视射线的交点 ,但反过来 ,相应的透视射线的交点上却未必存在着真实的粒子。换言之 ,示踪粒子与其像点相应的透视射线相交的交点间一般并不存在一一对应的关系。本文讨论了在给定透视中心和透视平面位置的条件下 ,由多幅不同光轴的PIV图像上的粒子的透视像点来确定粒子物点是否存在意义上的可确定性 ,并讨论了PIV图像上粒子像斑密度、尺度及其中心测量精度对粒子物点可确定概率的影响。

The determinability of particle's positions in 3-D PIV with multi-visual-line prospective image

In 3 D PIV it seems certain that the position of a particle seeded in a flow field can be determined by the particle's prospective images obtained respectively by multi cameras along different visual lines. The particle would be placed at the cross point of prospective rays that respectively pass the centers of the particle's prospective images and originate the lens centers of corresponding cameras, the prospective centers. The problem is that although the particle must placed at a cross point of all the prospective rays originated the different prospective centers, however, there not will be a particle at every the cross point. In this paper determinability of particle's positions in 3 D PIV with multi visual line prospective image is discussed. Meanwhile, the expression of determinable probability with size and concentration of particle images and measuring precision is given as well.