4 ms·

You should look more into how physically based rendering works. You do actually approximate the energy that reaches the different surfaces (in Watt / (m² sr))

You should look more into how physically based rendering works. You do actually approximate the energy that reaches the different surfaces (in Watt / (m² sr)) for all wavelengths of light using Monte-Carlo integration. You can send probes for different wavelengths separately if you care about the differences in the refraction index of your material by wavelength. Then you integrate the results by folding it with the corresponding color response of the primaries of sRGB or whatever color space you want to use. The color representation can be accurate, though screens etc are obviously limited.

shawn 8y ago
This is unrelated to the claim that multiplying two colors is meaningless.
- anonytrary 8y ago
  "Multiply colors" in pure physics is ill-defined, but we're talking bout a rendering engine. Engineers are allowed to make approximations whenever they want, and approximations aren't restricted from introducing new concepts/terminology. The closest thing to "multiply two colors" in physics would be taking a product state: |ψ⟩ = |ψ1⟩ ⊗ |ψ2⟩ Here, we are expanding a Hilbert space to include both unentangled particles (color == photon).
  - shawn 8y ago
    Engineers are allowed to make approximations whenever they want, and approximations aren't restricted from introducing new concepts/terminology. Well, yes. But in this case, the approximations are completely made up. They're not based on physics.
    - anonytrary 8y ago
      The RGB vectors are more or less based on biology, they're just a toy model[0]. Plus, physics is nothing more than a series of better and better approximations to things we observe -- it's all made up at some point. I'm guessing you're upset that the "made up" stuff in this case leads to no new physical insight and deviates from what we know to be more consistent with observation. That doesn't mean that "made up" stuff is not useful. Toy models are everywhere, even in fundamental research. There's a very good reason why people don't solve the kinematics of a tennis ball as if it were a 10^23 quantum-many-body problem. If you're constrained on time and money, the smartest thing to do is to get the closest result you can in the smallest time with the least amount of money. [0] http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colcon.html http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colcon.htm...
- phiresky 8y ago
  Where do you multiply colors in a PBR engine?

shawn 8y ago

This is unrelated to the claim that multiplying two colors is meaningless.

anonytrary 8y ago
"Multiply colors" in pure physics is ill-defined, but we're talking bout a rendering engine. Engineers are allowed to make approximations whenever they want, and approximations aren't restricted from introducing new concepts/terminology. The closest thing to "multiply two colors" in physics would be taking a product state: |ψ⟩ = |ψ1⟩ ⊗ |ψ2⟩ Here, we are expanding a Hilbert space to include both unentangled particles (color == photon).
- shawn 8y ago
  Engineers are allowed to make approximations whenever they want, and approximations aren't restricted from introducing new concepts/terminology. Well, yes. But in this case, the approximations are completely made up. They're not based on physics.
  - anonytrary 8y ago
    The RGB vectors are more or less based on biology, they're just a toy model[0]. Plus, physics is nothing more than a series of better and better approximations to things we observe -- it's all made up at some point. I'm guessing you're upset that the "made up" stuff in this case leads to no new physical insight and deviates from what we know to be more consistent with observation. That doesn't mean that "made up" stuff is not useful. Toy models are everywhere, even in fundamental research. There's a very good reason why people don't solve the kinematics of a tennis ball as if it were a 10^23 quantum-many-body problem. If you're constrained on time and money, the smartest thing to do is to get the closest result you can in the smallest time with the least amount of money. [0] http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colcon.html http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colcon.htm...
phiresky 8y ago
Where do you multiply colors in a PBR engine?