主页 Forums Games202-高质量实时渲染 作业四疑问

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    • #8785 Score: 0
      Moon
      Participant

      课程中提到u是sinTheta,为何作业中注释显示乘cosTheta。
      计算Eavg的时候不是只需要Eu*u*2就行么,得出来的结果相差很大啊。

    • #8808 Score: 0
      YunHsiao
      Participant
      13 pts

      μ 的定义感觉这里其实还是没那么严谨的,Kulla Conty 原作里面注释说 μ 就是 cos(θ):

      Notice that I’m using the Greek letter µ for the cos θ term here.
      This is just to avoid too much trigonometry in the slides and
      it’s closer to how the formulas are actually implemented.

      E_avg 我理解也应该是不需要做 sample 的,因为已经有了加权平均的过程……

      • This reply was modified 3 months, 3 weeks ago by YunHsiao.
      • This reply was modified 3 months, 3 weeks ago by YunHsiao.
      • #8843 Score: 0
        Ryushinn
        Participant
        2 pts

        1. 无论u是cosTheta还是sinTheta,Eavg的式子都可以写成2 * \integrate{ E(u) * u du },所以采用课程的定义或者作业框架的定义应该都可以

        2. 我也认为框架给的求Eavg这部分代码有点奇怪,我是直接Eu*u*2了,最终得到的结果比参考图要亮,不知道LZ是不是也偏亮。
        而且个人感觉作业文档的Eavg参考图好像是错的:Eavg的图整体要比Emu的图暗一些(把两张图并排对比,roughness大的部分尤为明显)。

        // 编辑:要在主楼里回复的..搞错辽….

        • This reply was modified 3 months, 3 weeks ago by Ryushinn.
        • This reply was modified 3 months, 3 weeks ago by Ryushinn.
      • #8846 Score: 0
        Migo
        Participant

        μ是cos(θ)或者μ是sin(θ),最后推导出来的积分式都是一样的,所以问题不大

    • #8854 Score: 0
      Neon
      Participant

      mu是sinTheta,所以mu*dmu*dPhi=sinTheta*cosTheta*dTheta*dPhi,采样是对w的,dw=sinTheta*dTheta*dPhi,所以最后只剩一个cosTheta,个人理解是这样,不知道对不对。

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