14 Ray Tracing 2 Accelerate

Acceleration: Bounding Volumes

  1. Ray-Intersection With a Box
    • Understanding : box is the intersection of 3 pairs of slabs.
    • Axis-Aligned Bounding Box: AABB 轴对齐包围盒
    • 光线进入所有包围面，进入盒子。出去其中一个包围面，出去包围盒。
    • $t_{enter}=max{t_{min}}, t_{exit}=min{t_{max}}$
    • If $t_{enter}<t_{exit}$, ray stay a while in the box.
    • $t_{enter}<t_{exit} and t_{exit}>=0$, ray and AABB intersection.
  2. Grid Solution: 在bounding box 里面再弄一堆格子
  3. Spatial Partitioning Examples
    • Oct-Tree
    • KD-Tree
    • BSP-Tree
  4. Object Partitions & Bounding Volume Hierrarchy (BVH)
    • 根据物体来划分KD Tree
    • 一个物体只出现一次
    • 怎么划分：一种是选最长的轴划分
    • 怎么划分：两边分成近乎相同数量的物体

Basic Radiometry 辐射度量学基础，给光一个精确的度量，给出正确的结果

  1. Radiant Energy and flux (energy)
    • Definition: Radiant energy is the energy of electromagnetic radiation. It is measured in units of joules, and denoted by the symbol: $Q\ [Joule]$
    • Definition: Radiant flux (power) is the energy emitted, reflected, transmitted or received, per unit time. $\Phi \equiv \frac{dQ}{dt} \ [Walt\ or\ Lumen]$
  2. Radiant Intensity
    • Definition: The radiant (luminous) intensity is the power per unit solid angle (立体角) emitted by a point light source. $I(\omega ) \equiv \frac{d\Phi }{d\omega }$
    • 一个立体角上面的能量
    • Solid Angle: $\Omega \equiv \frac{A }{r^2} = sin\theta d\theta d\phi$
  3. Irradiance TBD
  4. Radiance TBD