My 3D background texture pokes through the edges of my raised model. How do I make it stop cleanly?

Why it happens

Most models thin out to nothing at their edges. When a model is set to Merge over a textured background, the software keeps whichever is higher at each point. Near the thin edge of the model the bumps of the texture are higher, so they show through and the outline turns ragged. If the model is set to Add instead, it rides up and down on every bump of the texture.

Fix 1: lift the subject above the texture

1. Put the texture on its own Level at the bottom of the Component Tree.
2. Put the subject on a Level above it, with the combine mode set to Merge.
3. Double-click the subject's Level and enter a Base Height a little greater than the height of the texture. The official documentation describes Level Base Height as the way to raise a set of objects above things that should appear behind them, and gives a textured area as its example.

This leaves a small step around the subject, which usually helps it stand out.

Fix 2: cut the texture away under the subject

1. Select the subject and use Create Vector Boundary From Selected Components to trace its silhouette.
2. Select the texture component, then the boundary vector last, and click Clear Component Inside Selected Vectors.

The subject now sits in a clean opening at its normal height. If you move the subject later, you must redo the cut.

Keeping the texture inside a border

• When you build the texture with Create Texture Area, select a closed boundary vector along with the seed component. The tiling is then limited to that vector. With no vector it fills the whole job.
• For a texture that already exists, select a closed vector, right-click the texture's Level and choose Clipping, then Apply. The clip is dynamic for the components, but if you move the vector you must choose Clipping, Update.

Pro tips

• Level Base Height is added after the Level's components are combined and is not included when those components are baked.
• Keep the texture low compared with the subject so it reads as background.
• For a texture inside a dished shape, see the entry on the Multiply combine mode.