Illuminate a scene with an Arnold area light.
- [Instructor] In this chapter on studio lighting in Arnold we will create a simple triangle set up to learn the basics. In this rendering, I have a key, fill, and backlight. And although the effect is of natural daylight, this is actually an impressionistic lighting scheme. In other words, we are not employing a photometric daylight system, but rather using studio techniques to achieve a desired dramatic result and it is plausible because it's physically accurate.
It's just as if we were using studio lights instead of natural daylight. We're not using a proper scientific daylighting simulation in this chapter so that we can art direct the shot a little bit more easily. We will look at scientific daylight in in another chapter on natural lighting. Let's create an Arnold area light outside the window to provide some backlight illumination. Arnold supports all Maya lights except for ambient and volume lights.
If we go into the create menus to lights, if you create a directional point spot or area light, it is rendered as an Arnold light and an Arnold section appears in the light's attributes. We also have the option of creating Arnold native lights that provide additional functions. Let's do that. From the Arnold menu, go to lights, and click area light.
It is created at the origin, but it is very small. My scene is modeled to one to one scale, such that a Maya unit is a centimeter. The area light is only one centimeter on a side. Additionally the area light's shape node is currently selected, so let's select the transform node, click in the perspective or front view anywhere to deselect the light and then click to select the light again and in the channel box let's rename it, click on the name field at the top and type in backlight.
To increase the size of the light, click and drag across the scale X, Y, and Z attribute fields to select them all, type in a value of 50 and press enter. Now the area light is 50 centimeters on a side. Scale Z is the length of a line that comes out from the area light, indicating the direction of the light. Let's take a look at that. Right click in the perspective view to make sure it's active and press the F key on the keyboard to frame the selected area light.
And then we can tumble around with Alt and left mouse button. I don't recommend turning on the lighting in the viewport because the exposure won't match your final rendering. We can enable shading with the five key. And textures with the six key. To preview the rendering, let's open the Arnold render view, go to the Arnold menu and choose render. And if you get the camera shape listed here, choose perspective shape from the list.
We see a black screen in the render view. Due to the default attribute values for the light and camera. The light isn't bright enough for the current camera exposure. Let's fix that with the light attributes. With the light still selected open the attribute editor, I'll use the keyboard shortcut ctrl+a and I've got the attribute editor displayed in a floating window to give myself a little bit more space. In the Arnold area light attributes, the most important switch here is normalize. When that's on, the total amount of light energy coming from this area shape will not change if you scale the size of the light.
What we want here, in this case, is the amount of light to change when we increase or decrease the light scale. Since we scaled the light up by a factor of 50 on a side, we should get more light if normalize is off. Turn off normalize. And now we can see something in the Arnold render view. To learn about the Arnold native area lights attributes, let's test how this works by shining it on the walls. Move the light over to the corner of the room up and away from the wall.
I'll close the attribute editor and go back to the channel box, set the lights translate x to 250. Press tab to go to the next field. Translate y 100, press tab again and to translate z a value of 50 and press enter. And then tumble around in the perspective view once again with Alt and left mouse and translate with Alt and middle mouse, and we want to frame it so we can see the light on both walls.
That's how to create an Arnold native area light and control whether or not energy is normalized when a light object is scaled.
- Arnold rendering concepts
- Lighting with Maya and Arnold lights
- Controlling exposure
- Filtering light with Gobo
- Light attenuation with Decay
- Image-based lighting with Skydome
- Exterior daylight with Physical Sky
- Arnold Standard Surface material attributes
- Mapping material attributes
- Rendering refractions
- Mesh subdivision and displacement at render time
- Shading effects such as ambient occlusion and vertex color
- Camera effects such as fisheye and depth of field
- Animation image sequence rendering