剪切矩阵作为基本变换的组合? [英] Shear Matrix as a combination of basic transformation?
问题描述
我知道旋转、缩放、平移等的变换矩阵.我也知道剪切变换的矩阵.现在,我需要剪切矩阵--
[1 Sx 0][0 1 0][0 0 1]
以其他上述转换的组合形式.尝试过搜索,尝试过头脑风暴,但无法罢工!谢谢!
剪切角 theta
的 x 剪切操作减少为旋转和缩放为如下:
(a) 逆时针旋转 theta/2
.
(b) 使用 x-scaling factor = sin(theta/2)
和 y-scaling factor = cos(theta/2)
进行缩放.
(c) 顺时针旋转 45 度
.
(d) 使用 x-scaling factor = sqrt(2)/sin(theta)
和 y-scaling factor= sqrt(2)
进行缩放.>
I know the transformation matrices for rotation, scaling, translation etc. I also know the matrix for shear transformation. Now, I need to have the shear matrix--
[1 Sx 0]
[0 1 0]
[0 0 1]
in the form of a combination of other aforesaid transformations. Tried searching, tried brainstorming, but unable to strike! Thanks!
The x-shear operation for a shearing angle theta
reduces to rotations and scaling as
follows:
(a) Rotate by theta/2
counter-clockwise.
(b) Scale with x-scaling factor = sin(theta/2)
and y-scaling factor = cos(theta/2)
.
(c) Rotate by 45 degree
clockwise.
(d) Scale with x-scaling factor = sqrt(2)/sin(theta)
, and y-scaling factor= sqrt(2)
.
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