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什么是中心投影 ?什么是平行投影 ?用灯光或太阳光照射物体 ,在墙壁或地面上就有一个影子 ,这就是投影的原始意义 .由于光源的不同 ,可以有两种不同的投影方法 .1 .中心投影 .光线是由点光源发出的 ,这样形成的投影称为中心投影 .如图1 ,设在光源O和平面M之间有一个三角形ABC ,
What is a central projection? What is a parallel projection? Illuminating an object with light or sunlight, there is a shadow on the wall or on the ground. This is the original meaning of the projection. Due to the different light sources, there can be two different projection methods. Center projection. The light is emitted by a point light source. The projection thus formed is called the center projection. As shown in Fig. 1, there is a triangle ABC between the light source O and the plane M.