Surfaceonly

Surfaceonly refers to representations or processing modes in which only the exterior surface of a three-dimensional object is stored, rendered, or analyzed, with interior volume data omitted. This term is used across computer graphics, geometric modeling, and related workflows to distinguish surface-focused data from full volumetric representations.

In practice, surface-only data often takes the form of polygon meshes, such as triangle or quad meshes, or extracted surface representations from volume data (for example, isosurfaces). It may also appear as export options in modeling or rendering software labeled surfaceOnly or similar, intended to reduce data size or to suit a renderer that operates on shells rather than solids.

Common uses include rendering optimization, where backface culling and shading calculations are performed only on surface faces, and collision or visibility testing where a surface is sufficient to represent geometry. Surface-only models are also employed in 3D printing workflows to create shells or lightweight exterior structures, and in visualization tasks where interior anatomy is irrelevant.

Key data considerations involve normals and winding order for correct lighting, texture coordinates if materials are applied, and ensuring manifoldness to avoid rendering artifacts. When derived from scans or volume data, surface extraction methods such as marching cubes or surface nets produce polygonal surfaces intended to approximate the exterior boundary.

Limitations of surface-only representations include the loss of interior topology and volume information, potential issues with watertightness or thickness for manufacturing, and the need for post-processing to repair non-manifold edges or gaps.