projective invariance

A group of projective invariants was derived based on the cross ratio of five coplanar points, and used to recognize planar polygons. Experimental results show that the invariants have projective invariance and can be used to recognize planar polygons effectively.

利用共面五点的交比，导出一组用于识别平面多边形的射影不变量，用这组不变量实现平面多边形的识别，实验结果表明，这组不变量具有射影不变性，可以有效地识别平面多边形。

互联网摘选

Depending on the special relationship between vertexes and their center in a regular polygon a projective invariance is formed to extract the rotational center of object.

并利用正多边形顶点与形心的关系约束形成射影不变性，用来自动检测目标的旋转中心。

互联网摘选

In the calibration of the system, a plan based on the principle of cross ratio invariance in algebraic projective geometry was used to calibrate the coded light planes.

在对编码投影光平面的标定过程中，提出利用代数射影几何中的交比不变原理对其进行标定的方案，并论述了标定原理。

互联网摘选