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3D 体积的随机 2D 切片
原标题:Random 2D slice from 3D volume
  • 时间:2012-05-24 21:01:46
  •  标签:
  • math

我想从计算机程序的一个 3D 音量中获取一个随机的 2D 切片, 用于生成噪音 。 我决定使用一个旋转矩阵, 据我理解, 必须是旋转组 SO(3) 的成员。 我如何创建这个组的任意成员?

最佳回答

选择三个随机值 u 1 , u 2 , u 3 0至1之间。

校对:Soup

  • w = sqrt(1 - u 1 sin(2pi*u 2 )

  • x = sqrt(1 - u 1 )cos (2pi*u 2 )

  • y = sqrt (u < sub >1 )sin (2pi*u 3 )

  • z = sqrt (u < sub >1 )cos (2pi*u 3 )

您可以使用 < a href=> http://www.flipcode.com/documents/matrfaq.html__54" rel="nofollow" 来生成合适的旋转矩阵。

    |       2     2                                |
    | 1 - 2y  - 2z    2xy - 2zw      2xz + 2yw     |
    |                                              |
    |                       2     2                |
M = | 2xy + 2zw       1 - 2x  - 2z   2yz - 2xw     |
    |                                              |
    |                                      2     2 |
    | 2xz - 2yw       2yz + 2xw      1 - 2x  - 2y  |
    |                                              |
问题回答

您可以绘制随机的 3D 矢量, 由三个独立的随机变量组成组成, 作为每个轴。 然后您可以定义此矢量为您随机的 2D 切片的正常矢量, 以及该 2D 切片与来源的距离。 我非常确定( 虽然没有正式证明), 此方法应该给可能的 2D 切片统一分布( 先前的语句基本上是非正式的 ) 。

编辑 : 第二个想法是, 您也许应该绘制一个独立的变量来表示 2D 切片 与源的距离。 否则, 您将会得到 2D 切片的分布, 而这些切片更有可能在离源的某个距离附近 。





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