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Volumetric Lights: Part One

Author: semidieu

Tools Needed

  • Poser5

Introduction

Creating a scene using volumetric lights can be done in three steps using Poser5. This tutorial will cover these steps in detail.

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Step 1 - Set the scene

The scene you are creating should not be rendered over the background. If you do so, the volumetric light won't show!

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Step 2 - Set the light

Go to the Properties tab of the light. The light you want to use for this effect must have the Atmosphere Strength set to 1. Also select the Spot option for the light.

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The Angle Start variable designates the angle at which the light intensity starts to diminish and Angle Stop variable defines the angle at which the light intensity drops to zero.

Notice that at the bottom of the cone, you can get some white light (the two bottom pictures).

The white patches occur when the cone gets too large or the light intensity is too strong, and are a normal effect of the rendering process. They are saturation points. In order to diminish this effect, you should reduce various other variables such as Angle Start, light intensity and atmosphere density.

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Finally, take care where you place the light and in which direction. As there are so many possibilities, I cannot cover them all. To start with, you should probably just use a light source above the object, shining down vertically on it, as in the pictures on this page.

Step 3 - Set the light parameters

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In this example, the light Intensity is set to 100%, the Volume Density set to 0.02 and Atmosphere Strength varies.

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In this example, the Atmosphere Strength is set to 1.0 and the Volume Density is set to 0.02. The Intensity of the light varies.

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Notice the difference between this example and the previous one: the highlights on the character are very different. In this example, because the light intensity is decreased, the highlights on the character are also decreased. In the previous example, the atmosphere strength is decreased. But the highlights are not changed!

Step 4 - Set the Atmosphere

In the Material Room, select Atmosphere.

Check the Volume On box.

Set the different Volume settings.

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Step 5 - Set the Atmosphere - Volume Density

This defines how strong the fog will appear. Greater values give a stronger fog effect. The effects of this value also depend on the Atmosphere Strength settings and the Intensity of the light.

The example below shows the Volume Density settings with a white light, Intensity 100% and Atmosphere Strength set to 1.000.

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Step 6 - Set the Atmosphere - Step Size

The cone of light calculated in slices: the Step Size value defines what the size of the step between each slice will be. Lower values give better results because the slices are close enough to each other to overlap, but increase render time. If you'reduce the Step Size by a factor of two, the rendering time should be about twice as long.

Take care: a value of zero means no volume!

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Step 7 - Set the Atmosphere - Noise

The Noise setting defines how grainy the atmosphere is.

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Step 8 - The infinite light

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You can also use the infinite light with the Volume on, instead of the spotlight option. When using this option, you should use very low Volume Density values.

For this picture, I used a Volume Density of 0.005 and an infinite light coming from the back, pointing towards the camera.

Thanks again to my friend Mark for correcting my horrible English.

This tutorial continues in: Volumetric Lights: Part Two.