The paper discusses also how to master rapidly its charting and chart reading based on the first Angle projection.
阐述了在学会第一角投影法的基础上，如何迅速地掌握第三角投影的画图和看图方法。
Since we defined the frustum, we know the Angle at which the sides of the frustum meet - this is the field of view we used to create the projection matrix in the first place.
确定好锥截体，我们就知道锥截体顶角的大小—这是我们在第一个地方用来创建投影矩阵的视场。
应用推荐