Convert CGR to STL

A slicer, inspection package, or mesh editor may require STL when the available CATIA model is only a CGR visualization file. Converting it produces a triangular mesh for sharing or printing, but does not restore CATIA’s parametric model.

What the CGR format is

CGR means CATIA Graphical Representation. CATIA V5 and related Dassault Systèmes products use it as a lightweight, faceted display representation for CATPart and CATProduct geometry, especially in large assemblies, DMU review, and product navigation.

A CGR is intended primarily for visualization. It generally does not retain sketches, feature history, assembly constraints, material properties, exact analytic surfaces, or the editable solid structure of the source CATPart. Its accuracy is limited by the tessellation settings used when the CGR was created.

What the STL format is

STL stores a surface as connected triangular facets. It is supported by most slicers, 3D printers, mesh-repair applications, inspection systems, and rapid-prototyping tools. Binary STL is normally preferable because it is substantially smaller than ASCII STL.

STL does not store units, colors, materials, assembly structure, tolerances, or parametric history. Coordinate values are commonly interpreted as millimeters, but the receiving application must assign the unit explicitly or the model may import at the wrong scale.

How to convert CGR to STL

Using CATIA V5

1. Open the CGR in CATIA, or open the CATProduct that references it. A CGR loaded only as a visualization cache may not be directly editable or exportable.
2. If the CATIA installation and license provide the relevant function, use the command commonly named Tools → Generate CATPart from CGR. The command location, supported CGR types, and required workbench vary by CATIA release and configuration.
3. Open the generated CATPart and check the recovered faceted body. Remove unwanted assembly components and inspect placement, missing faces, gaps, and the intended export scope.
4. Export the body using the available STL export command, commonly through File → Save As or the STL/rapid-prototyping workbench. Select Binary when offered and set the chordal deviation, sag, or tessellation tolerance. A smaller deviation represents curved geometry more closely but creates more triangles.
5. Open the STL in a mesh validator or slicer. Confirm the scale, triangle normals, closedness, separate shells, and surface count before manufacturing.

If the original CATPart or CATProduct is available, export from that source instead of converting the CGR. The original model allows a new, controlled tessellation and can preserve more accurate geometry.

Using a dedicated converter

CAD Exchanger is a suitable desktop or web option when its current format list explicitly includes CGR input and STL output. Import the CGR, select the required part or assembly components, choose File → Export, select STL, and set the available tessellation and binary-output options. Format support can differ between CAD Exchanger editions and releases, so verify CGR support before purchase or upload.

Other commercial CAD translators may support this conversion, but support must be checked for the exact CGR variant. MeshLab and FreeCAD do not normally read proprietary CGR files directly, so they are useful after conversion for inspection or repair rather than as dependable CGR importers. Online conversion is appropriate only for nonconfidential files; engineering CGR data may contain sensitive product geometry.

Quality and compatibility limits

The STL cannot contain more geometric detail than the CGR. If the CGR was generated with coarse display settings, curved edges may remain visibly faceted even when the final STL uses a fine export tolerance. A fine STL setting cannot reconstruct exact surfaces that were discarded before the CGR was created.

For an assembly, decide whether to export one combined mesh or separate STL files for individual components. Confirm the intended unit after import, because STL has no unit field. Before printing, check that the mesh is watertight, has consistently oriented normals, and contains no self-intersections, duplicate faces, internal shells, or unintended overlaps; repair tools may correct some defects but cannot reliably recover missing geometry.