Similar to the previous schemes, a three-step procedure was
adopted for the three-dimensional projection, consisting of world,
camera, and perspective transformations. In the world transformation,
four matrices were used for the rotation about the x, y, and z
axes and the translation. The world transformation was the product
of the translation and rotation matrices, with the translation
matrix applied first. A scaling matrix was also included to adjust
the magnitude of the matrix elements along each axis. The final
form is as follows: world transformation = translation rotation
scaling. After the world transformation was completed, a
camera transformation was performed by introducing viewer coordinates
and transforming the coordinates of each point from the
reference frame to the viewer frame. The camera transformation
was the reverse of the world translation and orientation transformations.
The result was multiplied by a perspective transformation.
In practical computer renderings, the viewer can select the distance of objects in a simulated view by considering the perspective
distortion. Therefore, to obtain a three-dimensional projection
on a two-dimensional screen requires the following matrix product:
perspective transformation camera transformation world
transformation.