Check, repair and convert meshes in Mesh Lab

Mesh Lab checks triangle meshes on your device: STL (binary or ASCII), OBJ and PLY files up to 30 MB and 500,000 triangles. It tells you whether a mesh is a closed solid, measures it, estimates print material and can repair or convert it. Nothing is uploaded. The same engine powers the 3D Mesh Analyzer, 3D Mesh Repair and 3D Mesh Converter tools, so the app and the tools give identical numbers.

Make a test file and open it

1. Choose Templates and open L-shaped counter.
2. Open Geometry and reusable recipes under the preview and choose STL mesh (mm). The file is called L-shaped-counter.stl.
3. Choose Mesh Lab in the toolbar. Under Mesh file (STL, OBJ or PLY), choose the file you just saved.

The status line reads L-shaped-counter.stl is watertight. and the list below the preview says The mesh is closed and consistently oriented (watertight). You can also choose a mesh with Open in the toolbar: STL, OBJ and PLY files go straight to Mesh Lab.

Read the report

The flat-shaded preview shows the mesh from the front right. Red faces point away from you; on a closed mesh you only see them through holes or where triangles are flipped.

• Topology: the counter has 12 vertices, 20 triangles and 30 edges, no open boundary edges, an Euler characteristic of 2 and Genus 0: one closed piece without handles.
• Geometry in mm: Volume (cm³) 2893500 and Bounding box size (mm) 2800 × 2200 × 900. The PCA box follows the main directions of the part; for an L shape it is larger than the axis box, because it is not a minimal box.
• Triangle quality: 1 means equilateral. Long thin caps give a minimum of 0.326 here; only values below 0.1 are counted as slivers.
• Material estimate: with PLA · 1.24 g/cm³ the solid part would weigh 3588000 g. Enter a value in Infill (%) to estimate a printed part instead: the shell is surface area × Shell thickness (mm), the rest is filled at your percentage.

STL files carry no units. If your model was drawn in inches, set Model units to Inches (in) and every figure updates.

When a mesh is not watertight

Export the Studio corner template the same way and open it. Now the list reports 2 edges are shared by more than two triangles., 5 vertices join separate surface fans. and The mesh has 16 separate parts. The desk and seat legs touch the tops they carry, so their surfaces meet at shared edges and corners. That is expected for an assembly of touching solids. Print services usually want them united in CAD or exported separately.

Repair and convert

Repair and download runs a fixed sequence: weld duplicate vertices, remove zero-area and duplicate triangles, make the winding consistent with outward normals and close holes up to Largest hole to fill (edges) with flat patches. The Repair report lists each change, and a before → after table shows what improved.

To try it on a broken file, run the first example of the 3D Mesh Repair tool (an open box with a flipped and a duplicated triangle) and choose Open Renderloom under Continue in a premium app. Mesh Lab opens with the repaired file and reports it as watertight.

Convert and download writes the mesh in the Output format you choose and converts from Model units to Target units for conversion, for example from inches to millimetres.

Use the mesh in a scene

Renderloom scenes contain editable solids, not arbitrary meshes. Insert bounding box as a scene solid adds a box with the mesh's exact bounding box, named after the file and tagged Mesh bounds, so you can check scale and composition against your other solids.