Noise is a common scanning artifact: small random bumps and ripples that make a surface look rough. Reduce Noise smooths these small irregularities while keeping the overall shape of the object. It works on meshes, point clouds and lines: the same Reduce Noise button is on the Mesh Repair, Points and Lines tabs, and the panel shows the modes that fit the selected object. Add Noise, in the drop-down next to it, does the opposite.
Reduce Noise moves points to smooth the surface; it does not delete stray points that float away from the scan. To remove those from a point cloud, use Select Outliers first.
Reduce noise
- Select one mesh, point cloud or line in the Scene tree.
- Open Mesh Repair › Reduce Noise (or Points › Reduce Noise, Lines › Reduce Noise). The panel opens on the right.
- Choose a Mode (see the table below) and expand Advanced to see its parameters.
- Click Apply and check the result. The panel closes after Apply. If the surface is still rough, open Reduce Noise again and apply it once more, or undo and raise Iterations step by step.
On a mesh, in every mode except Via Normals, the border of the mesh and the edges marked as creases do not move, and if part of the surface is selected, only that part is smoothed.
In this example, the mesh is covered with small irregular bumps.
Choose a mode
| Mode | Available for | When to use |
|---|---|---|
| Via Normals | Meshes (default) | Scans of objects with sharp edges and flat faces. It first smooths the normals and detects sharp edges, then moves the vertices to match, so edges stay sharp |
| Simple | Meshes, point clouds (default), lines (default) | The fastest mode for light noise. Works well with a few iterations, but the object shrinks toward its center with more iterations |
| Equalize Tri Areas | Meshes | A fast mode like Simple that also makes triangle areas more equal |
| Keep Volume | Meshes, point clouds, lines | A fast mode that prevents the object from shrinking as a whole. A good choice when you need many iterations |
| Planar Approx | Meshes, point clouds | Noise on flat areas: each local neighborhood is approximated by a plane |
| Quadric Approx | Meshes, point clouds | Noise on curved areas: each local neighborhood is approximated by a curved (quadric) surface |
Safe starting values
- Start with the defaults: Iterations 1 and Smoothness 0.5 (0.2 in Planar Approx and Quadric Approx). Apply once, look, then repeat. The panel remembers the values you used last time.
- Smoothness is the share of the way each point moves toward its smoothed position. The field stops at 0.5, because higher values make smoothing unstable; lower it for a gentler pass.
- Turn on Limit near Initial to set a Max Displacement: no point moves farther than this from where it started. Its default is 1% of the bounding box diagonal of the object; set it close to the size of the noise.
- In Via Normals, Gamma sets the amount of smoothing, and Beta sets how sharp the edges stay (lower is sharper).
Avoid shrinkage
Simple smoothing pulls every point toward the average of its neighbors, so a rounded object gets slightly smaller with each pass. To keep the size:
- Use few Iterations in Simple mode, or switch to Keep Volume for many iterations.
- In Equalize Tri Areas, keep No Shrinkage on (the default).
- In Via Normals, Guide Weight pulls points back toward their original positions; it must stay above 0.
- In any mode, turn on Limit near Initial with a small Max Displacement.
Mode parameters
Via Normals
This mode works in two stages. First, it computes a smoothed field of normals and detects discontinuities such as sharp edges. Then it moves the vertices to match the corrected normals. This removes noise while keeping important features.
| Parameter | What it does | Default |
|---|---|---|
| Fast Indicator Computation | Uses a faster, approximate version of the algorithm | On |
| Normal Iterations | The number of iterations to smooth normals and find creases. More iterations give better results but take longer | 10 |
| Point Iterations | The number of iterations to move the vertices to match the normals. More iterations give better results but take longer | 20 |
| Beta | How sharp the detected edges stay: 0.001 keeps sharp edges, 0.01 moderate edges, 0.1 smooth edges | 0.01 |
| Gamma | The amount of smoothing: 0 means no smoothing, 1 is average smoothing, higher values smooth more | 5 |
| Guide Weight | How strongly the points are attracted to their original positions, to avoid general shrinkage. Must be above 0 | 1 |
| Limit near Initial | Limits how far each point can move | Off |
| Max Displacement | Shown with Limit near Initial: the largest distance a point can move from its original position | 1% of the bounding box diagonal |
| Select creases | Selects the sharp edges detected during denoising, so you can check them | Off |
Simple
The fastest mode. It works well with a few iterations, but with more iterations the object shrinks toward its center.
| Parameter | What it does | Default |
|---|---|---|
| Iterations | The number of times the algorithm runs for each vertex. More iterations smooth more and shrink more | 1 |
| Smoothness | How far each vertex moves toward its smoothed position: 0.5 is half way. Values above 0.5 lead to instability, so 0.5 is the maximum | 0.5 |
| Limit near Initial, Max Displacement | Same as in Via Normals | Off, 1% of the bounding box diagonal |
| Relax Tetrahedrons | Meshes only: a vertex with only three neighbors is put in the plane of its neighbors | On |
Equalize Tri Areas
Moves vertices so that neighboring triangles get more equal areas. This smooths the surface and evens out triangle sizes. The parameters are the same as in Simple, plus No Shrinkage (on by default), which prevents the surface from shrinking after many iterations.
Keep Volume
Fast smoothing that keeps the object from shrinking as a whole. The parameters are the same as in Simple.
Planar Approx
Smooths the object by approximating each local neighborhood with a plane. The parameters are the same as in Simple, plus Neighborhood Radius, the radius of each local neighborhood. For a mesh, its default is about six times the typical triangle size.
Quadric Approx
Smooths the object by approximating each local neighborhood with a quadric (curved) surface. The parameters are the same as in Planar Approx.
Example
Here is a noisy mesh before smoothing.
And here is the same mesh after Apply in Simple mode with 10 Iterations and 0.5 Smoothness.
Point clouds and lines
The same Reduce Noise panel opens for a point cloud or a line; only the list of modes and parameters is shorter.
- Point clouds: Simple (selected each time you open the panel), Keep Volume, Planar Approx and Quadric Approx. Neighbors are found within a radius that MeshInspector computes from the density of the cloud; in Planar Approx and Quadric Approx you can change it as Neighborhood Radius. Relax Tetrahedrons and No Shrinkage are not shown.
- Lines: Simple and Keep Volume, with Iterations, Smoothness, Limit near Initial and Max Displacement. A line with long segments has few points to move; to smooth it more evenly, split the segments first with Lines › Subdivide.
Add Noise
Add Noise moves every point of the object by a small random amount. It is useful, for example, to test how a workflow handles a noisy scan. Click the arrow next to Reduce Noise and select Add Noise. It is available for meshes, point clouds and lines; on a mesh or a point cloud with a selection, only the selected part gets noise.
The Add Noise panel has one parameter, Sigma: the magnitude of the noise. Its default is the bounding box diagonal of the object divided by 256. Click the Add Noise button in the panel to apply it.
Here is a clean model before Add Noise. We will use a Sigma of 0.35 mm.
After Add Noise with 0.35 mm, the mesh is noisy.
