If you're comfortable on the Edit page, you're used to thinking in layers. You stack clips on top of each other in the timeline, and the one on top is what you see. Fusion works differently. Instead of a stack, it uses a node graph, which is essentially a visual flowchart for your effects. Each task, like a blur or a color correction, is a separate box called a node. You connect these nodes with pipes, directing the flow of your image data from the starting point to the final output.

This might seem complicated at first, but it offers far more control and flexibility. You can easily see the entire structure of your composite, reroute connections, and make changes anywhere in the chain without disrupting the whole project. The two most fundamental nodes are MediaIn, which brings your clip from the timeline into Fusion, and MediaOut, which sends the final result back to the timeline. Everything you build happens between these two points.

The most common task in compositing is combining images. In Fusion, the Merge node is the primary tool for this. When you create a Merge node, you’ll see it has several inputs, but three are key. Fusion uses a color-coded system to keep their functions clear.

Here's what each input does:

• Yellow: This is the background input. Think of it as the main pipe or the bottom layer of your composite. It's the image that everything else gets placed on top of.

• Green: This is the foreground input. Whatever you connect here will be layered over the image coming through the yellow input.

• Blue: This is the effect mask input. You can connect a shape, a color channel, or another image to this input to control the visibility of the foreground. For example, connecting a white circle shape to the blue input would make the foreground image appear only within that circle.

The core rule is simple: green over yellow. This logic is the foundation of building composites in Fusion.

As you add more nodes, your graph can quickly become a tangled mess of pipes. Keeping it organized is essential for a professional workflow. The first step is managing the pipes themselves.

Sometimes, a direct connection between two nodes will cross over many others, creating confusion. To solve this, you can add a Reroute node. To create one, hold Alt (or Option on Mac) and click on any pipe. A small, flexible joint will appear that you can move around to redirect the pipe and maintain a clean, readable layout.

For bigger projects, you can use Underlays. These are colored boxes you can place behind groups of nodes to visually section off parts of your workflow. For example, you could put all the nodes related to keying inside a green underlay and all the nodes for color correction inside a blue one. To create an underlay, right-click in the node graph, go to Add Tool, and select Underlay.

You can also add Sticky Notes to your graph to leave comments or reminders for yourself or other artists. This is incredibly helpful for explaining a complex setup or noting why a certain value was chosen.

Sometimes you need to apply the same effect or transformation to multiple elements. Instead of duplicating the node and changing each one manually, you can use an Instance node. An instance is a linked copy. If you change a parameter on the original node, every instance of it will update automatically.

To create an instance, copy a node (Ctrl+C) and then paste an instance (Ctrl+Shift+V). The instance will have a green line under its parameters, indicating they are linked to the original.

What if you want to link most parameters but change just one? You can de-instance specific attributes. Right-click on a parameter in the Inspector of an instance node and select De-instance. This will break the link for that specific parameter only, allowing you to customize it while keeping all other parameters linked to the original.

Finally, Fusion has a powerful feature for managing your view. You don't have to send everything to the MediaOut node just to see it. You can view any node in the graph by dragging it into one of the two viewers. Alternatively, you can select a node and press 1 to load it into the left viewer or 2 to load it into the right viewer. This is essential for comparing your image at different stages of the composite, like viewing the original clip in one viewer and the final result in the other.

Understanding how to build and manage a node graph is the key to unlocking Fusion's power. It's a different way of thinking, but one that rewards you with precision and control.