Persona

A copy of the avatar's silhouette, offset and painted in a shadow colour behind the body. This is the graphic-design kind of drop shadow, not the kind lighting computes — it does not land on the floor and it does not move with your lights. It is just an offset silhouette

The shadow helps separate the avatar from the background, particularly when a transparent stage overlays a busy OBS scene

Both offsets are measured as a percentage of the frame height, so the shadow keeps its relative position when the window is resized or the aspect changes. The default 3 % / 3 % is a down-and-right cast that is visible the moment you enable it

Size applies a gaussian blur to the cast silhouette, measured in output pixels. The default 0 keeps the hard-edged VTube Studio backlight; raising it spreads the edge, and larger values approach the soft shadow a real light source would cast

The shadow is drawn outside the avatar’s silhouette and does not cover the avatar itself. It has its own opacity, so it remains visible in a transparent window

Examples

A long offset at low opacity reads as a soft lift; an offset under 1 % at full opacity reads as a hard sticker edge instead. Pick a saturated Color and push the offset out and you get the misregistered-print look

For an even band with no direction to it, zeroing both offsets does not work — that hides the shadow squarely behind the body. What you want is Outline

Processing Order

Drop shadow runs after rim light and outline, so the pixels either of those adds count as part of the silhouette being cast — a wider band grows a wider shadow. It runs before chromatic aberration and every colour stage, so the shadow grades with the image