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Question Variance Shadow Maps

Discussion in 'Graphics Dev Blitz Day 2023 - Q&A' started by Peter77, May 24, 2023.

  1. Peter77

    Peter77

    QA Jesus

    Joined:
    Jun 12, 2013
    Posts:
    6,641
    kripto289, NotaNaN and cLick1338 like this.
  2. SebLagarde

    SebLagarde

    Unity Technologies

    Joined:
    Dec 30, 2015
    Posts:
    936
    Hi,
    Variance shadow map and others like exponential shadow map, have pros / cons like any algorithm.
    They are good at allowing large kernel filter (i.e blurring for soft shadow), but there is a lot of light leaking that it hard to fix - in particular it depends on the distance between objects which is hard to control in a dynamic world.

    For a generic engine like Unity, it make sense to stay with PCF fitlering as it have less instability, i.e it is easier to predict the result. So the choice isn't about the quality, but more about the ease of setup and predictability.

    Still HDRP pipeline use exponential shadow map for area light shadow as it is a good compromise of performance / quality in this context (large blur kernel can't be achieve with PCF), and we accept the light leaking there