Simply hold the camera directly overhead while looking through the viewfinder. Frame the page as much as possible while keeping the horizontal and vertical edges as straight as possible.

一边观察取景器，一边直接将相机举过头顶，尽量在将横边和竖边保持垂直情况下选定图像。

youdao

Above, the camera is placed perpendicular to the train pavilion bridge. This creates a lot of horizontal and vertical lines in the image as opposed to diagonal lines dominating the composition.

在上图的表达中，一点透视所产生的很多垂直和水平的线条与画面中的斜线产生对比，突出了要表达的斜线元素。

youdao

In this instance, the location of camera in the world coordinates is unnecessary to calibrated, and the rotary matrix and horizontal movable matrix is needless too.

这种情况下不需要标定摄像机在世界坐标系的位置，相对的对于世界坐标系的旋转矩阵和平移矩阵也不需要。

youdao

It turns out that the unit we were testing only had motion controls mapped for moving the camera up and down, and relied solely on the analog stick for changing the horizontal view.

ENGADGET: blogger-avatar