An offset constructs a curve, surface, or region at a chosen distance from another geometric object. In signed distance functions (SDFs), dilation makes a shape larger by subtracting a distance, while erosion makes it smaller by adding one. section 10.2.3 section 10.6
SDF_dilated = SDF - offset SDF_eroded = SDF + offset
For a true distance function, these two assignments implement dilation and erosion directly. section 10.2.3
Use offsets differently depending on the geometric representation:
- SDF offsets are simple and computationally inexpensive, but Boolean operations destroy true distance values; applying the same arithmetic afterward can produce incorrect geometry, such as sharp instead of rounded crescent horns. section 10.2.3 section 10.2.5
- CAD offsets become substantially harder when offset curves or surfaces intersect, increasing both computational complexity and performance costs. section 11.1.2
- Chamfering combines curve offset, surface generation, and Boolean-like removal; filleting uses a Bézier-guided surface that preserves initial tangents. section 11.1.2
Organic shapes from an offset parameter
A metaball model can combine three points into a smooth organic-looking shape; one offset number controls the figure’s thickness. section 10.3.3
