Light3D

3Dv1app

Overview

A light in the scene — point, spot, distant (sun), rect, or dome (ambient). Authored as a standard UsdLux prim, so the viewport, Render3D, USD export and the Unreal bridge all read the same light. Zero lights in a scene = the neutral headlight rig.

How to

How-to

Pick the type (point, spot, distant, rect, dome); set intensity and exposure.
Spots take cone_angle / cone_softness; rects width / height; shadow casts a map in the viewport and Render3D.
Name a Light3D (or a Merge3D of several) in a BS_Relight's lights to relight a plate with it.

Inputs

Input	What it takes
in	the image this node works on

Outputs

Output	Type
out	Scene

Parameters

Parameter	Type	Default	What it does
tx	Float	0.0	Translate X — position along the world X axis, metres.
ty	Float	0.0	Translate Y — position along the world Y axis (up), metres.
tz	Float	0.0	Translate Z — position along the world Z axis, metres. The camera looks down −Z.
rx	Float	0.0	Rotate around X, degrees.
ry	Float	0.0	Rotate around Y (turntable), degrees.
rz	Float	0.0	Rotate around Z (roll), degrees.
sx	Float	1.0	Scale along X. 1 = unchanged.
sy	Float	1.0	Scale along Y.
sz	Float	1.0	Scale along Z.
type	Choice	point	What kind of light: point (a bulb, falls off by inverse-square), spot (point + cone), distant (parallel sun rays — position doesn't matter, rotation does), rect (a soft panel, single-sided), dome (even ambient fill everywhere). `pointspotdistantrectdome`
intensity	Float	1.0	Linear brightness multiplier on the colour. For point/spot lights this is the value at 1 meter — expect to push it well past 1 to light something a few meters away.
exposure	Float	0.0	Stops on top of intensity: +1 doubles the light, −1 halves it. The knob a grade-minded artist reaches for.
color	Color	[1.0, 1.0, 1.0, 1.0]	The colour.
radius	Float	0.5	The source's size in meters — and the floor on inverse-square falloff, so intensity stays finite right at the bulb.
cone_angle	Float	25.0	Spot only: the cone's half-angle in degrees off the light's aim (−Z).
cone_softness	Float	0.2	Spot only: how much of the cone's edge fades (0 hard … 1 fully soft).
width	Float	1.0	Rect only: panel width in meters.
height	Float	1.0	Rect only: panel height in meters.
shadow	Bool	false	Make this the shadow-casting KEY light. One light gets the 2k shadow map — the first enabled spot or distant in the scene; point/rect/dome can't cast in v1.
shadow_bias	Float	0.0015	Depth-compare trim against shadow acne (surfaces speckling in their own shadow). Raise it if flat surfaces sparkle; too high and shadows detach from their objects (peter-panning).
texture	Text		Dome only: a latlong image (EXR, HDR, PNG) the dome lights with instead of a flat colour — the environment a render sees, as the viewport's HDRI is the one the viewport sees (UsdLux inputs:texture:file, so it exports). Intensity scales the map, the dome's yaw turns it; the colour knob is ignored while a texture is set.
disabled	Bool	false	Bypass: the node passes its first input through untouched (D in the graph). The knobs keep their values for when it comes back.
label	Text		A note shown under the node in the graph — what this node is FOR. Never affects the render or the cache.
hide_input	Bool	false	Draw the node without its input wire — a tidy graph for a node whose source is obvious (a Dot, a viewer tap).