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Lighting and Rendering with mental ray in Maya with Eric Keller shows how to master practical mental ray techniques for rendering models created in Maya. This course walks through the most efficient and innovative mental ray techniques, including direct versus indirect lighting methods, creating different types of shadows, using the new ShadowMap camera, and reusing shadow and final gathering maps. A chapter on optimizing render times and enhancing render quality is also included. Exercise files are included with the course.
This movie is a basic review of how to create lights and the different light types in Maya. All of these light types will work with mental ray. But just to give some background here, I just want to go over how to add these lights in the scene and how they look when you render with mental ray. There're six basic light types that you can use when rendering with mental ray in Maya. And I'd like to demonstrate some of the aspects of each type of these lights. I have a basic Maya scene here of a tree on a hill.
And I'm going to add some lights to the scene and just render, just to show you what each light looks like. I'm going to set up my panel so that I can see my Outliner, along with my Perspective view. So I'll just go into Panels > Saved Layouts > Presp/Outliner. I can see the outliner here. And you'll find the lights are actually here on the Rendering menu. We have an icon for each. There's the Ambient Light, Direction Light, Point Light, Spot Light, Area Light and Volume Light.
The next thing I'd like to do is make sure that I've set up to render with mental ray. So to do that I'm going to go to Windows > Render Settings, and I'm going to set Render Using to mental ray. And the other thing I'm going to do is there's an option down here on the Common tab at the very bottom called the Default Light. And this Default Light is just there so that if you add objects to a scene, you can render it without having to add a light, but in some cases this can actually interfere with the appearance of mental ray lights.
So I'm going to turn this off, so that when I render, I know that I'm seeing just the lights that I add to the scene and nothing else. Close this. And I'm going to start with an Ambient Light. Now the purpose of the Ambient Light is to just add secondary lighting effects in the scene, like bounce light. It's a very old light type that's been around since the earliest versions of Maya. And I'd just like to mention that this light type is something that most professional CG artists don't use because it has the effect of flattening the scene, especially when you start to add additional lights. But I'd like to demonstrate it nonetheless, just so you can get an idea of how it works.
So I've just added it to the scene by clicking on this icon. And I've just used the Move tool to drag it up a little bit to position it, so I can see the icon. And I'm going to click on the clapboard to create a quick render. So there, we can see the ambient light. And it looks okay, but it's not terribly interesting. So I think that is all I'm going to use the ambient light for. And I can actually turn the light off by hiding it, just by turning off the light switch. So I'm going to hide it by doing Ctrl+H - and then this is the same on Windows as it is on Mac.
And now I'm going to click on this icon to create a directional light. And here it is. I'm going to pull it up so that I can see it. Now the directional light is meant to simulate light from a distant light source, such as the sun or the moon. As the icon indicates, the light beams from a directional light are all parallel. And this is how a very distant light source works in the real world. When you're using a directional light, the main thing to remember is that the rotation affects where the light is coming from, but position and scale have no effect on the way the light works.
So I can put it anywhere in the scene, and it's not going to change the way the light works. It's only the rotation. So I'm going to do a quick render with this light, so can sort of see how it works. I currently don't have any shadows on. I'm just using the light without shadows, but we can see that the light is hitting the tree from this orientation right here. If I rotate it, let's say like this, and create another render, you can see the difference. Now the light is coming down, like that.
So I'm going to store this image by clicking on this icon, so you can compare it with other renders. And I'm going to close the Render View and hide this light using Ctrl+H. Now I'm going to create a point light. The point light simulates light coming from an infinitely small source. So this is good for things like candle flames for creating particular moods, or things like Christmas lights, something that's very small but sheds light in all directions. In this light, the position of the light is very important and how it affects the scene, but rotation has no affect and neither does scale.
So I'm going to render this, so we can see how the Point Light looks. Again, I don't have any shadows turned on for this. It's just the light. So I'm going to store this image. And we can see that it's shedding light from in front of the trees, so something like a campfire, something like that would be good for a point light. Now that I've stored this image, I can compare it with the directional light. And you can see the difference there in how the two lights work. Hide this. And I'm going to hide this light again, which will turn it off, and create a spotlight.
So here is my spotLight. I'll pull this up using the Move tool so we can see it. And the spotlight, just like the name suggests, simulates light coming from a particular source. We can think of this as like a stage light, or a flashlight, or a car's headlight. And these are all good uses for spotlights. The position and the rotation are both going to affect how the light looks in the scene. I can position this in several ways. I can use the Move tool to put it in the scene. I can use Rotate to point the light.
And if I want to get a little bit more precise control, I can click on Show Manipulators. And this will give me a move for the light as well as a way to end the light, which can be very useful. So if I render this, we'll see how it looks. And we can see, with this light, a falloff here that is determined by the cone angle. So you can imagine that light is actually coming out of this source, and it's cone shaped.
And this is the effect that we get. I can change to radius of the cone angle using this value right here in the Channel box. If I set this to 60, we'll get a wider angle on the cone. You can see that there. If I click on Show Manipulators and click on this little icon right here, this will actually go through different manipulators. So I can change the cone angle interactively by dragging this back and forth, and it's this little blue light switch that cycles through the various settings of the light.
So if I click on this once, I get these controls. If I click on this two more times, I can control the cone angle that way. And the one other thing that I'd like to show about working with this light is if I want to have absolute control over what this light is actually looking at, I can actually look through the light as if it was a camera. So to do that, I'll go to Panels > Look Through Selected Camera. It's a little confusing, since I have other light selected and not a camera, but it basically is going to turn the light into the camera for a brief moment in time. So now I can see what the light looks like.
And I can actually position it and rotate it this way to get an idea of how it's going to work in the scene. And now switch back to the Perspective view. And I can see the light has changed now. So I'll render that one more time, and we can take a look at it. And this is what I end up with. So I'm going to hide this light. And I'm going to create an area light and switch to the Move tool. Pull it up in the scene so we can see it. The area light is like an array of lights, think of this as a square panel as a way to shoot light into the scene.
So a good use for this would be something like a fluorescent light that's recessed in the ceiling or maybe a TV screen or something like that. If I pull this back and do a quick render, we'll see how this light works in the scene. So you can sort of see it's actually coming out from this square and shooting light into the scene. If I pull this forward a little bit, you can actually see, let's say the light is actually in the middle of the tree here. So imagine a television stuck in the tree, and this is the kind of lighting you might get out of that.
It stops right here, right where the border of the light is. And we can compare that with the point light and the directional light. I'm going to hide this and finally create the volume light. And pull this up with the Move tool. And the volume light creates light within a specified volume, in this case a sphere. This is great for creating mood light. So if I render this, you can see that actually it will create light, but the light will only exist within the spherical volume.
As you can see, it's fairly dim. So I can increase the Intensity. I'm just going to scroll down in the Channel box to the Light and set this Intensity to 5 and do another render. And we'll see it gets a little bit brighter. So you can think of this as an opposite of a point light. Where the point light will shoot out in all directions, this will actually shoot within a spherical volume. And it's great for special effects. I would like to point out that I can hide this by doing Ctrl+H. And I'm going to show this, again, turn it on by doing Shift+H. It's the same on Windows as it is on Mac.
I want to mention that with the case of the area light, the position and the rotation are obviously going to affect how the light works. And in this case the scale will also affect the intensity of the light, as well as the shape of the light coming out. And it's the same with the volume light. I'm going to hide this, Ctrl+H, show this Shift+H. The scale will affect where this sheds light in the scene. Its position will affect where it sheds light in the scene, and the rotation, not so much, because it's a spherical volume.
If I go into the Attribute Editor for this light by clicking on this icon, I can change the shape of the light. So instead of a sphere, I can turn this into a box. And in this case, rotation is going to affect with the way the light works in the scene. It's not terribly obvious in this particular scene. So that is basic review of the different light types that are available in Maya. These all work with mental ray. As we go through the chapters in this title, we'll start to see how you can change settings to really fine-tune the way that these lights work with mental ray, because some of them have special properties that will improve the way they work within a scene.
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