the principal points meaning in English

要点

The principal points of a thin lens coincide at the center of the lens .
薄透镜的两个主点与透镜中心相重合。
Those are the principal points i want to explain to everybody
这些便是我要向大家解释的要点。
In this paper , we discussed the self - calibration method that no skew is present and the principal point is close to the center of the image but the focal length can be changed freely
本文讨论了在摄像机不存在畸变、主点已知而其它参数可以改变时的自定标算法。
There has been an obvious outbreak in the amount of calamity report and making it in public . meanwhile , the principal points of news outstand greatly . however , an obstacle to progress still exists
当前中国媒体灾难新闻的报道量、透明度有很大突破,报道中新闻的主体地位增强,同时也存在一定的阻力。