Tutorial-LumeLight

The LumeLight set is made up of six individual shaders: Illumination, Translucency, Glare, Glow, Night, and Beam. This tutorial will show you a few quick examples of how to use each one.

Part I: Let There Be Light

Part I of this tutorial will show you how to create a lantern's light, using Illumination, Translucency, and Glare.

Set up the objects

Open the scene. We've created the objects for you to work with.

Choose Get -> Scene. In the LumeTutorials database, get the scene called "LightScene1."

Add a light.

Choose Light -> Define. Set the light's Colour to R: 1.0, G: 1.0, B: 0.76. Set the Start Fall off to 0.0, and the End Fall off to 10.0. Change the Shadows Type setting to "Raytraced", and turn the Umbra Intensity all the way down, to 0.0. Click OK to create the light.

Translate the light to x: 0.0, y: 0.6, z: 0.0.

Preview! Let's see what we've got so far.

Choose Preview -> All. Remember these are mental ray shaders, so make sure that in your Preview -> Setup you've got the preview renderer set to "mental ray."

You'll see that what we have so far is a light shining through a metal grid work, and a partially transparent layer of glass but it's too dim on the metal and doesn't effect the glass at all!. Now time for the shaders

Add the shaders

Add the Illumination shader to the light. This will provide a realistic fall off.

With the light selected, go to Light -> Edit. In the lower left side of the Edit Light dialogue box, click on the "Shader" check box; then go to the LumeTools database, and choose Illumination.

Click the edit button to go to the Illumination dialogue box; change the Brightness to 0.5 and then click OK, and OK again to go back to your scene.

Preview!

Notice how the light's fall off is now correct brighter in the center, dimmer at the edges, with a realistic r-squared fall off in between. Now to fix the glass -

Add the Translucency shader to the glass layer. This will give the glass a translucent glow, according to the brightness of the light inside.

Select the glass layer. This is the yellow object towards the middle of the lantern; to make sure that you've selected the proper object, go to Info -> Selection and see that the object's name is "Inner Glass."

Choose Material. Notice that the Transparency is set to 0.5, which is what we want for this particular glass. Click on the Material Shader check box; then go to the LumeTools database, and choose Translucency. Click OK to go back to your scene.

Preview!

Now you should see that the glass layer is glowing, lit by the light from the inside. Definitely better, but we're not quite there yet

Add the Glare shader. This will give us a nice glare effect.

Chose Render. Make sure that your Rendering Type is set to "mental ray." Then click on Options to go the mental ray Options dialogue box.

In the Output Shaders box, click on the Select button; then go to the LumeTools database and select Glare.

Click the edit button to go to the Glare dialogue box and change the Spread to 1.4. Everything else looks OK, so click OK, then Accept and Accept again to go back to your scene.

Preview! Note that when you preview, mental ray will now use the Glare shader that you set in mental ray Options. Also, Glare is one of the few LumeTools shaders that takes up a bit of processor time you'll see that once the image is done rendering, it will take a short while for Glare to makes its calculations, before adding its effect.

That should look like a real lantern notice the overexposure and glare effects around the edges of the glass, and the metal grid work towards the middle . If you've got a few minutes, for more realistic shadows you might want to change your light to be an area light. Here's how you'd do it:

Create soft shadows.

With the light selected, go to Light -> Edit. Click the Area Light check box, change the Geometry setting to Sphere. Leave the Area Sampling at 3 by 3. Click OK to create the light.

Scale the light to about ScaleX: 0.2, ScaleY: 0.2, ScaleZ: 0.2. (This will shrink the area light so that it fits into our lantern.)

Preview! This will take a little while, as area lights are computationally intensive.

This image more accurately renders the soft shadows that would be cast by our translucent glass layer, which is essentially a broad light source. If you've got the time and want an even nicer image, try rendering with Antialiasing turned on.

Now that we've covered the first half of the LumeLight shader set, let's go onto the second half...

Part II: Strangeness in the Night

Part II of this tutorial will show you how to use the Beam and Night shaders.

Get the scene.

Get the NightLight Scene. We've set up most of the objects for you.

Choose Get -> Scene. In the LumeTutorials database, get the Scene called "LightScene2." You'll see that the scene is made up of simple, abstract shapes; this is solely for purposes of the tutorial as with all the shaders, these work especially well with photo realistic renderings.

Preview! Let's see what this scene looks like.

Choose Preview -> All. Again, these are mental ray shaders, so make sure that in your Preview -> Setup you've got the preview renderer set to "mental ray."

OK, as you can see we've got three colored spheres, set on a wooden tabletop, lit from an overhead spotlight and a very dim infinite light. Also notice that we have a completely invisible cone in the scene. Its point lies directly on top of the spotlight, and its sides coincide with the light coming from the spotlight. This cone will hold our light beam.

Add the Beam shader

Add the Beam shader to each cone.

Select the cone and choose Material. First, check to make sure that the transparency is set to 1.0. Then click on the Volume Shader check box, go to the LumeTools database, and choose Beam.

Click on Beam to highlight it, then click the Edit button. In the Beam dialogue box, first change the fog density to 0.75. Then go to the Lights box and click on the Select button; you will see a list of the lights that are in this scene. Choose "spot1" to associate the light to the cone, then click OK and go back to your scene.

Preview!

You should now see a fog-effect on the light. Notice that the overall rendering time is practically uneffected by the addition of the Beam shader, unlike when using traditional volumic light effects. For the last step in this tutorial we will make the camera behave the way your eye does in low lighting conditions. First let's take the beam out of the way -

Delete the cone.

With the cone selected, choose Delete -> Selection.

Add the Night shader.

Add the Night shader.

Choose Camera -> Settings. In the Lens Shaders box, click on Select; then go to the LumeTools database and choose Night.

Click the edit button. In the Night dialogue box, leave the Multiplier at 3.0, and set the Cutoff to 0.06. Click OK to exit, and OK again to return to your scene.

Turn down the dim light.

Select the infinite light (it's located close to the scene's origin).

Choose Light -> Edit. Dim the light by changing it's Colour settings to R: 0.015, G: 0.015, B: 0.015.

NOTE: The Night shader works by increasing the brightness of the dark areas of your scene, which in turn provides a desaturated appearance; therefore, in order to keep the dark areas of your scene appropriately dark, we've turned down the light that is illuminating the dark areas.

Preview!

Notice how the colors in the darker areas are now desaturated, just as they would appear to your eye in reality; for a discussion on how the Night shader simulates your eyes' rods and cones, check out the Reference Manual.

Part III: Sorry, But We Gotta Get Glowing

Part III of this tutorial gives a very simple example of how to use Glow.

Get the scene.

Get the Glow Scene.

Choose Get -> Scene. In the LumeTutorials database, get the Scene called "LightScene3." You'll see that once again the scene is made up of simple, abstract shapes; and again, this is solely for purposes of the tutorial as with all the shaders, these work especially well with photo realistic renderings.

Preview! Let's see what this scene looks like.

Choose Preview -> All. Again, these are mental ray shaders, so make sure that in your Preview -> Setup you've got the preview renderer set to "mental ray."

So far we've got three, green-stained wood spheres, lit by a dim infinite light; and now

Add the Glow shader

Add the Glow shader. We're going to make one of our wood spheres glow as if lit from within by a green light.

Select the sphere farthest to the camera.

Choose Material. Click on the Material Shader check box, go to the LumeTools database, and choose Glow.

Click on Glow to highlight it, then click the Edit button. In the Glow dialogue box set the Color to R: 0.0, G: 1.0, B:0.0. Make sure that the Mix is set to "Mix with underlying," then click OK to exit, and OK again to return to your scene.

Preview!

The third sphere now appears to be lit from within. Very pretty.

That's it for the LumeLight tutorial!