Learn how to apply advanced lighting and background options.
- [Instructor] The environment controls in the Arnold renderer settings give us a great deal of flexibility. In this case, we'll light the shot with Arnold physical sky, but use a bitmap for the background and reflections. Because we're making the adjustments in the render setup dialog, we can't really use active shade. We'll need to do a production rendering. Let's open up the render setup. I'm in target production rendering mode rendering the physical camera. Click render. Here's our physical sky from the last exercise.
And let's clone this so we have something to compare with. Click on clone rendered frame window and just push that off to the side. Back in the render setup, in that Arnold renderer tab we can scroll down a bit and we're looking for environment, background and atmosphere. The default mode is physically based and we could put a separate background in here if we wanted, but the background would not show up in reflections.
And to make that happen, we can go into advanced mode. Up here choose advanced and now we have two sections here: environment, lighting, and reflections (or IBL) and that's a sky dome light. Scroll down and we've also got settings for the background or backplate and it's also set to the scene environment by default. So let's change that. Instead of scene environment here let's choose custom map and click the custom map no map button and the material map browser, under maps general double click on bitmap.
In the current project scene assets images, select the env_sky image, and that's an EXR document, and click open. In the open EXR configuration dialog just click okay. And now our background plate has been applied. Let's render that. The background has been applied, but its parameters are not correct by default. Let's fix that by going into the material editor. And drag the custom map from the render setup dialog over into the slate material editor view and choose instance, double click the bitmap node, and rename it, call it env_map.
The first thing that we see with our rendering here is that it is way too dark so let's increase the brightness in the material parameters. Down at the bottom we have output. Open that, set the output amount value to 30, and do another rendering. The background image is bright enough. Let's also change it's mapping. Back in the top of the map parameters we have the coordinates rollout. The default mapping here is screen so let's change that to spherical environment.
And we also want to flip the image left to right so set the tiling value to negative one in the u-axis. U-tiling of negative one. And do another production rendering. Now the backplate is working. It's not providing any lighting in the scene, that's still coming from the physical sky, but we've got a different image in the background. We want that image to appear in reflections as well. Back in the render setup dialog, in the environment, lighting, and reflections section scroll down a bit and you'll find emit/affect.
And these are the various components of their rendering. We don't want the physical sky to provide the specular reflections so turn specular off. Scroll down a bit more into the background/backplate section and enable specular reflections there. And do another production rendering. Okay very good, we've got the setup we want, which is the lighting is coming from the physical sky but the background and reflections are coming from the image.
And let's compare that with our previous render. We can verify that, in fact, the physical sky is providing the lighting. I'll close this clone, go back over to the material editor, and I've got the physical sky instanced here in the view already. Double click on that and we've got the enable sun switch. Turn that off and just do a production render to test it. And we can see that, indeed, when we turn the sun off in the Arnold physical sky, we get no direct illumination from the sun.
So that proves that our lighting is coming from this simulated daylight here. So I'll re-enable the sun. We can close the material editor. One last thing I'd like to point out is you have the choice of whether you want to anti-alias these edge pixels against the background or against black and that's done by going into the Arnold renderer section and in the background/backplate we can turn the camera visibility off. And under these conditions, the background will not show up in the rendering here.
And that way our alpha channel will work a little bit more predictably if we want to comp this in in post. So click render. We've turned the sun back on, but we've turned the background off by disabling camera primary rays. And now these edge pixels are going to anti-alias against black instead of against the background color that we saw a moment ago. That's how to use the advanced mode in the Arnold environment settings to light the scene with the physical sky, but render a custom background and reflections.
- Arnold rendering concepts
- Arnold lights such as quad, spot, and distant
- Modifying Arnold object properties
- Filtering light with the gobo filter modifier
- Image-based lighting with Skydome
- Daylight simulation with Physical Sky
- Arnold Standard Surface material parameters
- Diffuse, opacity, and bump mapping
- Rendering refractions with Transmission
- Building an Arnold shading network
- Test rendering with utility map
- Mesh subdivision and displacement at render time
- Atmospheric perspective with scene environment fog
- Rendering a spherical environment with VR Camera