How do I make one part of a relief look like it sits in front of another without making the whole model thicker?

Why it happens

With Merge, whichever shape is higher wins where two shapes overlap. If both are about the same height, neither reads as being in front. The obvious fix is to lift one with Base Height, but that raises the whole component on a flat plane, adds thickness to the model and leaves a wall around its entire edge. Low relief works by lifting or lowering only the area where the overlap happens.

The three controls (Component Properties)

• Base Height: raises the whole component. Use it sparingly, when a piece really must stand proud everywhere.
• Tilt: raises one end. The official documentation describes it as the way to lift part of a component above another where they overlap without raising the whole thing, which avoids a deep wall around the edge.
• Fade: lowers one end. The documentation describes it as a way to make an area appear to go behind another component.

Steps

1. Double-click the component in the Component Tree to open Component Properties.
2. For the piece in front, check Tilt, click Set Anchor, then click two points. The first click is the pivot that stays put (place it away from the overlap). The second click is the point that gets raised (place it on the overlap). Adjust the angle until the piece just clears its neighbor.
3. For the piece behind, check Fade, click Set Anchor, then click two points. The first click stays at full height. The second click is the point the shape fades toward (place it under the overlap). Set the percentage to control how far it drops. The fade is linear between the two points.
4. Look at the 3D View from a low angle and adjust. Small amounts usually read better than large ones.

Pro tips

• To lift a whole set of parts above a background, put them on one Level and give the Level a Base Height. The official documentation gives raising objects above a textured area as the example.
• Tilt and Fade stay editable until you bake. Baking makes them permanent, which then lets you apply a second tilt or fade on top (see the entries on baking).
• If the heights still fight each other, check the Combine Mode first (see the entry on combine modes).