Soft stacking" generally refers to a method of layering images or other data where the ordering of elements can vary smoothly across a region, rather than being fixed in a single, global order. It's an alternative to traditional, rigid image stacking, allowing for more nuanced and flexible compositions.
In more detail:
Traditional Stacking:
In traditional image compositing, layers are stacked in a strict order, like a deck of cards. Each pixel is either entirely behind or entirely in front of other pixels.
Soft Stacking:
Soft stacking allows for a more fluid, "fog-like" layering effect, where elements can appear partially in front of and partially behind other elements within the same pixel and across the image.
Applications:
Soft stacking is useful for creating more realistic and natural-looking composites, especially when dealing with translucent or semi-transparent elements.
Technical Implementation:
Soft stacking typically involves augmenting each pixel with stacking coefficients that represent the relative ordering and transparency of different layers at that specific point.