4 — Depth maps and effects

Aphelion has a family of Depth Generator nodes that synthesise depth passes, and a family of Depth effects that consume one through a depth input. This tutorial builds a depth pass, drives it with animation, and uses it for parallax, fog, defocus, and slices.

Where depth comes from. Aphelion does not estimate depth from ordinary video. A depth map is a grayscale frame you supply or generate: procedurally (below), from a rendered depth pass via Image Input, or from a matte painted with Roto/Shape Tracker. Everything in this tutorial works with any of those sources.

Part A — Build a depth pass

A depth effect wants a frame where white = far (or near, per the effect's Invert Depth toggle) and black = close.

Option 1: a gradient backdrop

1. Add a Depth Gradient. Its outputs are a depth frame:
   • Gradient → Near = 0, Mid = 0.5, Far = 1.
2. Add a Depth Noise (Noise → Scale = 32, Noise → Seed = 0) and a Merge to add surface variation, or feed the noise into a Displace for lateral detail.
3. Preview it by connecting Depth Gradient.depth → Viewer.frame.

Option 2: a shaped object

1. Add a Depth Shape and set Shape → Shape to the primitive you want.
2. Follow it with Depth Noise for organic break-up.

Option 3: volume / position passes

Part B — Drive a flat plate with parallax

Depth Parallax offsets pixels by depth, which reads as a 2.5D move.

1. Chain: Video Input → Depth Parallax → Viewer.
2. Add Depth Gradient and connect Depth Gradient.depth → Depth Parallax.depth.
3. Animate the move:
   • Parallax → Shift X = 0 → 40 over the shot.
   • Parallax → Shift Y = 0 → -15.
4. Keyframe Shift X/Shift Y at the start and end frames (see Keyframes).

Near pixels move more than far pixels, so the frame gains depth without a 3D render.

Part C — Depth-driven effect stack

Add these after the plate, each with the same depth pass wired into its depth input. Effects are independent — use the ones the shot needs.

Using Depth Slice as a matte

Depth Slice outputs a mask, not a frame:

1. Video Input → Depth Slice.depth (wire your depth pass in).
2. Add a Merge; background = your far background, foreground = the plate.
3. Connect Depth Slice.mask → Merge.mask.

Now only the depth band you selected shows the plate; the rest is the background. Scrub or keyframe Slice → Near/Far to rack focus between planes.

Part D — Composite the depth layers

A common pattern is to split the shot into two depth bands with two Depth Slice nodes (one inverted), grade each separately, then Dissolve between them driven by a value.

Dissolve → Dissolve → Mix accepts 0–100 and can itself be keyframed, giving a depth-racked transition.

Troubleshooting

Related

• Normals and relighting — turn a depth pass into a normal pass.
• Driving properties over time — animate depth controls procedurally.