Reverse Engineering Objects with Metashape: From Scan to CAD

Reverse engineering physical objects into editable CAD models is invaluable in manufacturing, product design, and quality control. By combining photogrammetry with Agisoft Metashape’s powerful processing engine, you can generate accurate meshes from photographs and convert them into parametric CAD geometry. This guide walks you through the end-to-end workflow: from capture to Metashape processing, mesh cleanup, and CAD import.

1. Why Use Photogrammetry for Reverse Engineering?

Traditional 3D scanning methods—like structured light or laser scanners—can be expensive and require specialized hardware. Photogrammetry leverages standard cameras (DSLRs, mirrorless, even smartphones) and software to produce high-resolution 3D meshes at a fraction of the cost. When accuracy of a few tenths of a millimeter is acceptable, Agisoft Metashape is an ideal solution.

2. Step 1: Prepare and Capture Photos

Success begins with high-quality images. Follow these best practices:

• Lighting: Use diffuse, even illumination to minimize shadows and highlights.
• Background: Place object on a neutral, textured surface for easier masking.
• Overlap: Capture 70–80% overlap between consecutive photos around the object.
• Angles: Shoot from multiple elevations and azimuths—top, sides, and oblique angles.
• Stability: Use a tripod or turntable to maintain consistent framing.

3. Step 2: Process Images in Agisoft Metashape

Import your image set into Metashape and execute the core photogrammetry workflow:

• Align Photos: Use “High” accuracy to generate a precise sparse point cloud.
• Build Dense Cloud: Choose “Medium” or “High” quality with mild depth filtering.
• Build Mesh: Generate a 3D mesh from the dense cloud (Depth Maps → Arbitrary surface).
• Build Texture: Bake high-resolution textures (optional for CAD but useful for reference).

After these steps, you have a detailed, textured 3D mesh of your object.

4. Step 3: Clean and Simplify the Mesh

Photogrammetric meshes are often dense and contain artifacts. Before exporting to CAD, clean them:

• Delete Noise: Use Rectangle or Lasso selection to remove floating points and stray geometry.
• Fill Holes: Apply Tools → Mesh → Close Holes for small gaps.
• Decimate: Reduce polygon count to a manageable level (e.g., 500k–1M faces) via Mesh → Simplify or external tools.
• Ensure Manifold: Check for non-manifold edges and overlapping faces; repair if needed.

5. Step 4: Export the Mesh for CAD

Export your cleaned mesh in a CAD-friendly format:

• OBJ: Includes geometry and optional UVs/textures.
• STL: Widely supported for solid modeling; ideal if no texture needed.
• PLY: Preserves color and normals; less common in CAD tools.

In Metashape, go to File → Export → Export Model and select your format with appropriate units and precision.

6. Step 5: Import and Retopologize in CAD Software

Once in your CAD or modeling environment (e.g., Rhino, SolidWorks, Fusion 360):

• Import Mesh: Insert the OBJ/STL into your workspace.
• Retopology: Use polygon reduction or quad remeshing tools to create a cleaner mesh.
• Surface Fitting: Fit NURBS or CAD surfaces to the mesh—use tools like Rhino’s ScanTo3D or SolidWorks’ Surface Wizard.
• Parametric Modeling: Trace key edges and features to rebuild in native CAD geometry (planes, cylinders, fillets).

7. Tips for Accurate Reverse Engineering

• Scale Correctly: Use GCPs or known dimensions/scale bars to set accurate size in Metashape before export.
• Maintain Tolerances: Keep mesh deviation under your CAD tool’s tolerance (e.g., ±0.1 mm).
• Use Reference Markers: Place coded targets on parts for precise alignment between scans and CAD.
• Check with Calipers: Verify key dimensions on the physical object to validate the 3D model.

8. Applications and Case Studies

• Heritage Preservation: Reverse engineer architectural details or artifacts for restoration.
• Tooling and Manufacturing: Create CAD models of legacy parts lacking CAD drawings.
• Quality Control: Compare manufactured parts against reverse-engineered CAD for deviations.
• Custom Prototyping: Use scanned shapes as foundations for new design iterations.

Conclusion

By leveraging Agisoft Metashape for photogrammetric scanning and a structured cleanup and CAD import workflow, reverse engineering real-world parts becomes accessible and cost-effective. From detailed mesh generation to parametric CAD modeling, this pipeline empowers engineers and designers to recreate, analyze, and innovate on existing objects without expensive dedicated scanners. Follow these steps to streamline your reverse-engineering projects and unlock new possibilities for design and manufacturing.