---
title: "Light Linking"
canonical: "https://documentation.chaos.com/space/VRAYHOUDINI/113279828/Light%20Linking"
format: markdown
---
This tutorial shows you how to link lights to objects in V-Ray for Houdini. Want to follow along but don’t have a license?  Overview By default, all lights illuminate all objects in a scene, and all objects cast shadows from all lights. However, for artistic purposes or scene optimization, you may want to modify this behavior. This can be achieved through light linking, which allows you to control how lights interact with specific objects. Linking lights to objects is done through the Light Linker tool or from the lights and objects parameters. Linking lights to objects lets you control: which lights illuminate which objects (Light Mask); which objects cast shadows from which lights (Shadow Mask); which objects are reflected in other objects (Reflection Mask). The Light Linker provides finer control by letting you choose a work mode. You can choose which objects are illuminated by a light (light-centric mode) or which lights light an object (object-centric mode). For reflections, you can choose the reflector-centric or reflection-centric mode. Find more information about the Light Linker tool at the  SideFX documentation . Workflows Illumination Method 1 - Through Object Parameters Select an object and navigate to its  Render tab > Shading subtab > Light Mask . Add the lights that you want to affect this object. For example, for  box_g  add  light_g  in the  Light Mask  field. Method 2 - Through Light Linker Click    > New Pane Tab > Light Linker  to open the  Light Linker  pane. Set the  Light Type  to  Light Mask . Select a  Mode  from the dropdown. For this tutorial, the Mode is  Object-Centric . This means that you must choose which lights illuminate the object. Select an object from the  Lit Objects  filter list. Then select the lights that must illuminate the selected object from the  Light Sources  filter list. For this tutorial, the  box_g  object is selected, and then the  light_g  is selected. This means that the green light illuminates the green box. You see that the Light Mask field in the Render tab is automatically populated with the name of the light that illuminates the selected object. box_g illuminated by light_g box_g illuminated by light_b box_g illuminated by light_g, light_b, and light_r Shadows Method 1 - Through Lights Parameters Select a V-Ray light, navigate to its Shadows parameters, and enable  Shadows . In the  Shadows Mask  field add the objects that should cast shadows. For example, select  light_g  and add  box_g  under the Shadows Mask field. This means that the green box casts shadows from the green light. Method 2 - Through Light Linker Click   > New Pane Tab > Light Linker  to open the Light Linker pane. Set the  Link Type  to  Shadow Mask . Select a  Mode . Here, the  Object-Centric  mode is kept from the previous example. Pick an object from the  Shadow Caster  list that casts shadows. Pick lights from the  Light Sources  list. For this tutorial, the  box_g  object is selected, and then the  light_g  is selected. This means that the green box casts shadows. You see that the Shadow Mask field in the V-Ray Light tab of the selected light is automatically populated with the name of the object that casts shadows. No Shadow Shadow Reflection Method 1 - Through Object Parameters Select an object and navigate to its  Render tab > Shading subtab > Reflection Mask . Add the object that you want to affect this object. For example, for  box_g  add  box_g  in the Reflection Mask field. Method 2 - Through Light Linker Click    > New Pane Tab > Light Linker  to open the  Light Linker  pane. Set the  Link Type  to  Reflection Mask . Select a  Mode . Here, the Mode is set to  Reflection-Centric . Pick an object that should be reflected from the  Reflection Objects  list. Pick an object(s) to reflect from the  Reflector Objects  list. You see that the Reflection Mask field in the Render tab is automatically populated with the name of the object that should be reflected by your object.