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# V-Ray Mesh Light

## Introduction

This lesson will take you through converting a piece of geometry into a Mesh Light

The information centers around the use of the VrayLightMesh

This lesson topic is approximately 20 minutes in length

Lesson covers all 3 Learning Cycles for the Lesson Topic – Lecture, Demonstration, and Activity.

Learning Outcomes: You will be able to light a scene with a VRayLightMesh and understand how to adjust the settings to create the look you want in your renders

## Contents

Overview
Available Materials
Lecture

## Overview

Goal - You will learn how to use the Mesh Light V-Ray Properties to turn any geometry into a direct light source.

Objective – We will light a scene with geometry converted to a light surface and understand how to adjust it to get the desired results.

Outcome – You will know how to create a V-Ray Mesh Light from a piece of geometry in your scene.

## Lecture

### 1. Terminology

Lighting is important to our lives and our 3D scenes. Without it we can’t see anything!

• Intensity
• How strong the light will be in the scene
• Color Temperature
• A real-world measurement of the hue of a light
• Light isn’t just about where is shines but where it doesn’t

### 2. Light

• Lighting in the real world
• Larger lights will have softer (more diffused) shadows
• Lights with irregular shapes

• Light Falloff
• Real lights have Decay
• Light falls off to the square of it’s distance – Inverse Square Law
• An object at 2x the distance away from a light will receive 1/4x of the light it would at 1x distance
• An object at 3x the distance away from a light will received 1/9x of the light it would at 1x the distance

• Light Temperature
• Use the temperature value to create the right mood for your scene

### 3. Mesh light

a) Light Overview

• Intensity is the overall strength of a light
• The Units used affect if the amount of light emitted by the V-Ray light depends on its size
• Color vs. Temperature
• Which mode to use depends on what results you want
• Texture
• Allows for more detail or colors in the light than from the basic parameters

• The VRayLightMesh allows you to create direct mesh based lighting in your scene
• Allows you to create light sources that have volume and shape without the need to use self illuminated objects and global illumination
• To convert a mesh to a light source you need to add the VRayLightMeshProperties node to it
• Select the object(s)
• Right click the Mesh Light button in the V-Ray Shelf and select the Turn selection into lights (apply single VRayLightMesh)

• If the VRayLightMesh is close to other surfaces in the scene, it is best to use it with GI enabled
• This will allow V-Ray to use combined direct and GI sampling of the mesh light for best results
• Without GI, the light may produce noisy results for surfaces that are very close to it

b) Intensity – controls the brightness of the light. The value and effect depends on the Units p

Units – controls the “meaning” of the Intensity parameter

default – the Intensity parameter directly controls the intensity of the surface of the light source.  This means that a bigger light will emit more total light than a smaller light with the same Intensity

Watts (and Lumens) – the Intensity parameter controls the total amount of light coming from light source. This means that a smaller light will appear brighter than a bigger light with the same intensity, however they will both emit the same amount of light.

c) Color Mode – specifies how we control the color of the light

Light Color – we directly set the color of the light using an RGB value

Temperature – the color of the light is determined using the Temperature parameter

d) Texture

Use Texture - tells the light to use a texture for the light surface. If there are surfaces which are close to a texture-mapped light, it is best to have GI enabled. This allows V-Ray to use combined direct and indirect sampling for the light, reducing the noise for surfaces close to the light.

Texture - specifies the texture to use

## Conclusion

• Mesh Light

a) GI if needed

b) Intensity – default or Watts (Lumens)

c) Color – RGB or Temperature

d) Texture

## Demonstration

Time to see it work!

Watch while I demonstrate how to create and adjust a Sphere Light in our miniature house scene

## Activity

Time to do it yourself!

Use the provided scene file to recreate the cinematic look as you have seen me demonstrate

Used values:

• Intensity Multiplier – 0.200
• Units – Watts
• Use Texture – enabled
• Texture – Star_noise