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## Introduction

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• This lesson will take you through setting up caustics with V-Ray
• This information centers around the basic caustics parameters
• The lesson topic is approximately 20 minutes in length
• This lesson covers all 3 Learning Cycles for the Lesson Topic – Lecture, Demonstration, and Activity
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## Overview

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Goal - Develop the look for a glass dog and his shadow. Use various caustics parameters to create different looks

Objective – We will use several parameters to set up and alter caustics in a scene

Outcome – You will understand how to work with the caustics parameters to  create a specific look

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## AnchorlecturelectureLecture

### 1. Terminology

Here are some terms to be aware of when thinking about caustics.

• Caustics
• Light reflecting or refracting off a curved surface
• Photon
• Unit or “particle” of light

Caustics vs. Refraction

• Caustics affect what the light does; Refraction affects the material
• Caustics affect highlights and shadows on nearby surfaces
• Qualities of refractive material affect appearance of shadow
• When caustic light passes through an object and hits a surface, highlights and shadows on surface are based on object’s reflective/refractive material properties

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### 2. V-Ray Caustics

a) Caustics Overview

• Turn on caustics in Render Settings window
• Change caustics settings for light
• Change refraction settings for material

A light’s attributes that affect caustics appearance:
• Caustics subdivs
• Refraction IOR and Fresnel IOR

Turn on caustics
• Render Settings > GI tab > Caustics rollout

b) Caustics subdivs
• Sets quality of detail in caustics; higher values give more detail
• Parameter found under settings for the light
• Effect is most easily seen with caustics render element

• Sets a radius in which the V-Ray Sun is going to emit photons to be used for the calculations of caustics
• Parameter found under settings for the V-Ray Sun

d) Refraction IOR and Fresnel IOR
• Parameters affect refraction for material, which in turn affects caustics

Effect is most easily seen with caustics render elementImage Added

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e) Dispersion
• Affects material
• Disperses light by wavelength, as with a prism
• Higher Dispersion Abbe makes the dispersion effect stronger
• Colors visible in caustic shadows

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## Conclusion

a) Caustics subdivs
• Level of detail for caustic effect
• A radius within each photons are traced
c) Refraction and Fresnel IOR
• Affects caustics via material the light passes through
d) Dispersion
• Scatters light into colors in material; affects caustics via material

## AnchordemonstrationdemonstrationDemonstration

Time to see it work!

Watch while I demonstrate how to set up caustics

Demonstration tutorial

## AnchoractivityactivityActivity

Use the provided  scene file to set up and adjust caustics.
We have also provided a final scene for your reference.

Dialing in the right values