Quad Light


Simulates light from an area source (a quadrilateral, specified by four vertices). Can be used to model light from an extended source (fluorescent strip lights) or in some circumstances from a window.

 

The lights page has more detail about the controls. The additional parameters are shown below. In addition to honoring the standard 3ds Max light parameters, the Modify Panel will also show the following parameters:

 

 

Spread

Emits light focused in the direction along the normal. The default spread value of 1 gives diffuse emission, while lower values focus the light more until it becomes almost a laser like beam at value 0. Currently fully focused laser beams at value 0 are not supported, there is always a small minimum spread. Low spread values can be noisier than the default high spread, so be careful when using them.

The animation below shows the effect when lowering the Spread value.

Spread value lowered from 1 (Quad light)

Quad X/Y

Defines the four corner points of the shape of the quad light. These vertices must define a flat and rectangular quad.

Portal

When enabled, this disables anything related to the illumination produced by the light object (a Portal doesn’t generate light), and the object now becomes a light portal.

Rollover image to view scene without light portal (skydome light only)

 

Skydome lights can use light portals to reduce noise for interior scenes, where the light comes in through relatively small openings. Instead of emitting light, they can be used to guide skydome light sampling. Light portals must be placed to cover all windows, doors and other openings through which skydome light comes into the scene.

 

The light portal should be oriented so that it is pointing in through the window as indicated below:

Light portal pointing inwards outside window

Skydome lights also have a portal_mode parameter with options off, interior_only and interior_exterior to respectively turn off portals, block any light outside portals for interior only scenes, and let light outside portals through for mixed interior and exterior scenes. Blocking light outside portals more predictably reduces noise for interior only scenes.

Roundness

Changes the shape of the light from a square at 0, to rounded corners, to a disk at 1.

 

Soft Edge 

Specifies a smooth falloff for the edges of the light. The value specifies the width of the soft edge, from no soft edge at 0, to smooth falloff all the way to the light center at 1. Works similarly to the penumbra_angle for spot lights.

 

 



Further Examples

Cars lit with large 'quad' area lights simulating soft box studio lighting


Quad light positioned in front of monitor (rollover image)

 

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