Posted on June 26, 2017, 12:54 a.m. by Lizendy • Last updated on June 26, 2017, 6:50 a.m.
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A simple guide to the "render layers" node in the compositor.
If you don't know what render layers are. They're basically outputs to all the individual passes that are made when you render.
To start you're going to need to enter the compositor. You do this by going into the node editor and pressing the little button that looks like a photograph at the bottom. On the screen, you will see the render layers node and the composite node.
To add more outputs to the render layers node, you need to go to the properties panel on the right and press the little photograph button at the top. Now go to the "passes" drop down menu and select any or all of the passes you want to be able to edit.
This is what you normally see when you render an image.
This is a mask that adds a gradient of mist from nearest to farthest from the camera.
This will show the normals of all the objects in the scene.
This will show a black and white image of all the shadows.
This will show a black and white image of the Ambient Occlusion in the scene.
The direct options for Diffuse, Glossy, Transmission, and SubSurface, will show the direct light hitting those objects.
The indirect options for Diffuse, Glossy, Transmission, and SubSurface, will show the indirect light hitting those objects.
The color options for Diffuse, Glossy, Transmission, and SubSurface, Will show the shadeless color of those objects.
This will only show any object that emits light.
An example of how this can be used is, connect the shadow output node to a math node and set the math node to multiply. Then mix the image output with the math node output, and set the mix to add and connect it the composite. With this setup you can adjust the strength of the shadows with the value in the math node. This is one of the simple things that you can do with the render layers, but obviously, if you're creative you can make some pretty crazy setups.
I'm not an expert on render layers so if there is and missing/wrong information, let me know and I'll fix it right away.