What is the different between ESM and CESM?

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Hello! You can see the functions used to compute ESM and CESM in shadowsFragmentFunctions.fx:

  • ESM : float esm = 1.0 - clamp(exp(min(87., depthScale * shadowPixelDepth)) * shadowMapSample, 0., 1. - darkness);
  • CESM: float esm = clamp(exp(min(87., -depthScale * (shadowPixelDepth - shadowMapSample))), darkness, 1.);

They look pretty similar to one another at a glance, but once you plot the values according to the shadowMapSample value, they look pretty different (for simplicity, I substituted depthScale and shadowPixelDepth for 1.0, and darkness for 0.0):

image
image3570×1915 326 KB

ESM is f1, CESM is f2. The link to the plots is here: Graphtoy

@sebavan can complement with anything I missed :smiley:

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