Polygon Mesh
Also called mesh, polygonal model, triangle mesh
A polygon mesh is a 3D shape built from many small flat faces, usually triangles or quads, joined edge to edge. Curves are not truly curved in a mesh: they are approximated, so the number of faces decides how smooth a rendered surface looks.
In other words, it is a shell of tiny flat panels. Use enough of them and the eye reads a smooth ring, use too few and the flats start to show.
How a mesh describes a shape
A mesh is a list of points in space and a list of faces connecting them. Nothing is stored about the inside of the object, only the skin. STL and OBJ files are both meshes.
Mesh density is the count of faces across a surface. A dense mesh looks smooth and takes longer to render. A sparse mesh renders fast and shows facets. On jewelry, where surfaces are small, curved, and highly reflective, the balance sits well towards dense.
Why mesh quality shows up in a render
Polished gold is a mirror. Any flat spot in the mesh reflects the light as its own hard patch, so a coarse mesh reads as a band with faint stripes running around it. Matte or textured surfaces hide the problem, polished ones broadcast it.
Gemstones are worse again, because light bounces around inside them before it comes out. A stone modelled with too few faces loses the crisp facet junctions that make a diamond look like a diamond.
If you export a mesh for us, use a fine setting. If you send a 3DM or STEP instead, we handle the meshing at our end and the question goes away.
- Watertight, with no holes or unjoined edges
- Dense enough that curves read smooth at full resolution
- No flipped faces, which render as dark or transparent patches
- No stray or duplicate geometry left over from modelling
Questions about Polygon Mesh
What is the difference between a mesh and NURBS?
A mesh approximates a shape with flat faces. NURBS defines it with maths, so it stays exactly smooth however far you zoom in. Rhino works in NURBS, STL and OBJ files are meshes.
How many polygons should a jewelry model have?
There is no fixed number. Export at a fine or high quality setting and check that the smallest curves, prong tips and milgrain beads, still look round rather than angular.