Control area light brightness, spread, and samples.
- [Instructor] Let's learn about the attributes of the Arnold native area light. I'll select the light in the perspective view and open up the Arnold render view. Because normalize is off, then the total amount of light is affected by the size of the light. Let's experiment, grab the scale tool, and scale it up in the Y-axis in the perspective view. And if we have a scale Y of about 200, we can see that we're getting more illumination.
Let's set that back down to 50. We can increase the amount of light using the traditional intensity value here, that we can see in the channel box shape node. That works in the ordinary linear scale that you're familiar with from standard Maya lights, but if you scroll down a little bit farther, you'll see another one labeled exposure. And that works in f-stops. Each single integer added to the exposure value doubles the amount of light emitted.
Let's set the exposure to one. Type in one and press enter. And now we've effectively got twice as much light in the rendering. To get to the remaining controls for the light, let's open up the attribute editor. With the light selected, open attribute editor with control + A. The most significant attribute here is the light shape, and it's defaulted to quad. We can select cylinder, which is great for fluorescent tubes. We can also choose disc.
And each one will have slightly different attributes available here. I'll set it back to quad and we've got a rectangular light once again. Next is spread. With a spread of zero, we will get rays coming from the light plane, exactly orthogonal to that plane. Turning this spread value down, and we're essentially focusing the light. If we bring it down to a value of zero, then we get a square of light on the wall there. Even with a spread of zero, the lighting will still become softer with distance.
So it's not exactly a columnated beam. We can't get a laser sharp focus using the spread parameter. However, as we'll see later in the chapter, we can achieve that effect using a Maya spotlight. Below the spread value is the resolution. That's the importance sampling for the texture maps. It controls the accuracy of HDRI image-based lighting. If you're using a flat color up here instead of a map, then you don't need to worry about resolution, it doesn't apply, and you can leave it at its default of 512.
The roundness attribute give us a round light instead of a square one. If I bring that up to a value of one, we get a perfect circle, because we started out with a perfect square over here. You may wonder, how is this different from a disc light type? Well, a disc shape does not have a soft edge attribute. If the soft edge value is zero, we get a uniform field of light across the whole rectangle or circle. With a soft edge of one, there's a fall-off gradient from the center to the edge.
The center of the light puts out full intensity illumination, and that diminishes to zero intensity as we approach the edge of the circle or rectangle. I'll bring the roundness back down to zero. And now we've got a square once again. And bring the soft edge down to zero also. For an ambient backlight effect, I would want the light to be scattered. So set the spread back up to one. That's how those area attributes work.
We've just set them all back to their default values now. I want this to be a very large light source outside the window. So let's set that up. I'll close the attribute editor. And with the light selected in its channel box, set the scale X to 1000. Press the Tab key, set scale Y to 500. Press Tab and set scale Z to 100. Press enter. Now it's quite a lot larger.
You can go up to the top view and right click there. And then frame that selected object with the F key. Let's move it. In its channel box, set translate X to zero. Press Tab. Translate Y 400, press Tab. And translate Z negative 600, press enter. And now it's been positioned pretty far out here, we can dolly back a bit. It's turned around the wrong way. Set rotate Y to 180.
Now let's take a look in the camera view. In the Arnold render view, choose camera shape one. And got some light coming in through the window. We can make that a little bit brighter. Over in the shape nodes, in backlight shape, set the exposure to two. And it's a bit grainy. We can fix that by going back to the attribute editor. Control + A. And increase the number of samples here. And that's going to really help with the grain. Set that to a value of five.
And that's how to set the basic attributes of an Arnold area light.
- 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