Volume Light Effects

This tutorial will show how to use LightUp Material properties to create Volume light effects.

The model is kept very simple so we can focus on the techniques. The first thing we are going to create is a Component to represent the light volume. We want to create a Cone shape - how you do this is a matter of personal preference, but you want to end up with something like this:

We are going to Paint the inside of the Cone with a Material with some high contrast detail to represent 'dust mites'. I'm going to use a standard SketchUp Material called "Stone_Granite_Midnite" for this:

SketchUp allows you to apply different materials to each side of a Face. We'll apply a totally transparent Material to the outside of the Cone allowing us to see inside our Light Volume.

Next we place the Component Axes at the apex of the cone so later we can rotate around the light source.

Using the LightUp Query tool, we need to prepare the materials for LightUp rendering. We don't want these Faces to cast any shadows from either material, so for both materials we check "Don't cast shadows". (I've just shown the dialog for the outer material here.)

For the inner material - that will be rendering the light volume - we want some special settings. As well as not casting shadows, we want the material to be "self-illuminating and brighten whats on screen behind it. So we check "Always fully lit" and "Additive glow":

Now we can embed a PointLightSource at the apex of our light volume Component in preparation for adding it to our environment. Open up the Component by double-clicking; I'm going to add the PointLightSource at the Origin of component Axes and set a IES light source. Make sure you place the light source on the inside of the cone.

We can use the LightUp Query tool to aim this component just as we can with IES PointLightSource. Choose Query Tool, Shift-Click on the volume light Component and Ctrl-drag on the point you wish to aim the light.

And the light is now rotated automatically to aim this point:

OK, now we're ready to try out and tweak our volume light effect. I've placed a couple in a model (with some sconce lighting on the back wall) to show the effect:

Starting Tourtool, you can see the faces that make the light volume don't cast any shadows and brighten up anything behind them. But the effect is far too strong - Additive effect like these need to be used quite subtly.

However, we can make all the changes we need inside Tourtool by navigating to the inside material and double clicking to open the Material dialog. Click on the Color adjustment, and bring down the Luminance slider as shown:

Lastly, we are going to add some animation to the material so the flecks of brightness in our material seem to float around like dust in a powerful light. We'll use Texture Animation, and choose "Ramp". I've also set the Angle of motion to 80 degrees which on this model is upward. You'll have to experiment with your model to find what direction your texture is laid out.

If you bring the camera in close, you can see the dust mites much more easily. Alternatively, change the scale of the Material you're using. You really need to see this animation in motion to appreciate the effect, so have a go!

Any questions, you can post on the LightUp forum or if you prefer, emailing LightUp directly.