Documentation / Node reference / geo nodes

geo/SDFTriangulate

Converts SDF geometry to a mesh, a solid, or, from a 2D field, its outline.

Sdf Operations

Samples the SDF field on a grid over its bounds and contours it. SDF objects already display as a raymarch without any node, so reach for this when the geometry itself is needed: to scatter or copy onto, to feed mesh operations, or to export. The grid extends one cell past the bounds on every side, so a shape that reaches the declared bounds still closes. Non-SDF objects are skipped.

**The input's dimension decides what comes out.** A 3D field gives a surface: a manifold solid by default, a triangle mesh (quads under dual contouring) with `as manifold` off. A 2D field gives its zero isoline: a 2D manifold cross-section by default, ready for geo/M2DBoolean and the M2D family, or SEGMENT geometry with `as manifold` off, chained into walk order and oriented with the field's interior on the left, which is what a curve fitter and geo/M2DCreate both want. Cost grows with the cube of the resolution in 3D, the square in 2D.

**If your shape has hard edges, set `method` to dual contouring.** Marching cubes, and marching squares in 2D, cannot produce a sharp edge at any resolution: they are only allowed to put vertices along the grid lines, and a box corner does not sit on one. Raising the resolution shrinks the bevel and never removes it, at eight times the cost per doubling. Dual contouring places one vertex per grid cell wherever the field says it should go, so edges and corners come out crisp at a resolution the other method would round off. In 3D it outputs quads; in 2D it also KNOWS which vertices are corners and publishes them as the `corners` point group.

**Cell size or cell count.** `cell mode` picks which one you give. A COUNT is relative to the shape's bounds: the same 32 covers whatever comes in, so a shape that grows meshes at the same triangle count and a coarser field. A SIZE is absolute: it is a tolerance in world units, and it holds when the shape changes. Size is the default because a part going to a printer is specified in lengths, and the mesh has to be finer than the layer height and the nozzle for the print to land on the model rather than on the meshing. The cap is a cell COUNT either way, so a size fine enough to ask for more cells than that gets coarsened and the node logs a line.

`isoValue` contours a surface other than the zero set: positive inflates the shape, negative erodes it, in both dimensions and for every output. mat/MeshSDF carries the same param, so the raymarched preview and the mesh can be looked at at the same level.

**If the field came from a volume, `gridFiltering` matters more than the resolution.** A field out of geo/SDFCreate is a grid of voxels, and TRILINEAR reads between them with a gradient that jumps at every voxel face: the mesh gets one facet per voxel and raising the resolution only makes the facets smaller. TRICUBIC reads with a continuous gradient and the faceting goes. It is 64 samples per read against 8, so it is a switch rather than the default, and a tree of analytic primitives ignores it entirely.

**The shading record comes with the mesh.** If the field carries per-region colours (see geo/SDFBoolean), the mesh gets `COLOR`, `ROUGHNESS`, `METALLIC` and `EMISSION` as POINT attributes, sampled at each vertex, which is what multi-colour 3MF and glTF export off an SDF model read. Only the channels that were given a value come out: a channel nobody set, uniform at its default across the whole mesh, is not written, so two coloured spheres mesh to a `COLOR` attribute alone. A field wearing ONE record writes its channels as OBJECT attributes instead, which is the same thing said once. A MANIFOLD output carries the same record: the colours ride inside the solid as vertex properties, survive a geo/M3DBoolean, and come back as those POINT attributes wherever the solid is meshed, under the same rule.

**The 2D output feeds geo/SDFCreate, which is how a 2D field gets a correct INTERIOR distance.** A field built from geo/SDFBoolean is exact outside but only a lower bound inside, with bands following the union's hidden seams. Contour it here, hand the manifold to geo/SDFCreate, and the result is the exact signed distance to this outline on both sides. Use dual contouring on the way if the shape has corners.

Parameters

Name Type What it does
method UInt8 MARCHING_CUBES · DUAL_CONTOURING Which contourer turns the sampled grid into geometry. Marching cubes, marching squares in 2D, is smooth and predictable and rounds every hard edge off, because it may only place vertices along the grid lines and a corner rarely sits on one. Dual contouring places one vertex per cell where the field actually points, so edges and corners survive; in 3D it outputs quads instead of triangles, in 2D it flags the corner vertices in the `corners` point group. Its faces follow the grid rather than the shape, so run geo/QuadRemeshAuto after it if you want good edge flow as well as sharp edges.
isoValue Float Contour the surface where the field equals this value instead of its zero set: positive inflates the shape, negative erodes it. A sphere of radius 1 comes out at radius 1.25 at 0.25, and at 0.75 at -0.25. The sampled bounds grow with a positive value, so the inflated surface still closes. It changes what is MESHED, not the field: mat/MeshSDF has the same param for the raymarched form.
asManifold Bool Output a solid instead of a mesh: .MANIFOLD_3D from a 3D field, so geo/M3DBoolean and the other M3D nodes take it directly, and .MANIFOLD_2D from a 2D one, for the M2D family. The field is clipped to its bounds so the result always closes, and normals are left to whatever triangulates it downstream, since a manifold carries no normals. Per-region colours DO carry: they ride the solid as vertex properties and manifold interpolates them through a boolean. Turn it off for a triangle mesh with normals from the field's gradient, or, from a 2D field, for chained segments.
cellMode UInt8 CELL_SIZE · CELL_COUNT Whether the sampling grid is given the SIZE of a cell or the NUMBER of them. A count is relative to the shape's bounds, so the same value follows a shape that changes size, holding the triangle count and losing accuracy. A size is a tolerance in world units and holds the accuracy instead, which is what a part headed for a printer needs: the mesh has to be finer than the layer height and the nozzle. The cap is a cell count in both modes, so a size that asks for more cells than that gets coarsened, with a line in the log.
uniformCellSize Bool Keep the grid cells cubic, sizing them from the longest bounds axis.
cellSize Float Edge length of one grid cell, in world units. It is the accuracy of the result: no feature narrower than a cell survives, and a corner is placed to within one. A shape 1 unit across at 0.05 is 20 cells across. There is a ceiling on cells per axis, lower in 3D than in 2D, so a size fine enough to exceed it is raised to fit and the node logs a line.
cellSizePerAxis Vector3 Edge length of one grid cell along each axis, in world units. A 2D field reads the x and y components and ignores z, the axis it is flat on.
resolution UInt32 Number of cells along the longest bounds axis. A 3D field is capped lower than a 2D one, because its cost is cubic rather than square; the node logs a line when it clamps.
resolutionPerAxis Vector3UInt Number of cells along each axis. A 2D field reads the x and y components and ignores z, the axis it is flat on.
gridFiltering UInt8 TRILINEAR · TRICUBIC How a grid field in the tree is read between its voxels. A grid field is what geo/SDFCreate makes from a volume, so a tree of analytic primitives never looks at this. TRILINEAR, the default, is 8 samples per read and has a gradient that jumps at every voxel face, which comes out as one facet per voxel on the meshed surface and, under dual contouring, as cell normals that disagree with each other. TRICUBIC is 64 samples per read and has a continuous gradient, so the faceting goes rather than gets smoothed away by a higher resolution. mat/MeshSDF carries the same param, so the mesh and the raymarched preview can be read the same way.

Examples

Scenes you can open in the editor that teach this node.

See also

This page is generated from the engine, so it describes the release you can download. The same text is in the editor's Help panel next to the node itself.