For many reasons, it may be useful to scan an existing object to use in CATIA. This could be for styling, to scan a clay model of a part, then use this as a starting point of a CAD part. Perhaps an old part that has no CAD model needs to be scanned and reverse engineered. Parts can be pulled from production, scanned, and compared to their CAD counterparts to check for accuracy.
Digitized Shape Editor (DSE) and Quick Surface Reconstruction (QSR) are the main workbenches in CATIA for dealing with scanned and point cloud data. DSE is used to import the scan and improve its quality, ultimately generating a mesh. QSR takes this mesh and converts it to surface data that can be used in other CATIA workbenches, such as Generative Shape Design or Part Design, as the basis of a new part.
Many types of scanners are available and will create a cloud of point data, typically in formats such as STL, OBJ, CGO, or ASCII. For this post, we’ll take a high-level look at the general procedure, which can be broken into the following general steps:
- Import Data
- Refine Point Cloud
- Generate Mesh
- Repair Mesh
- Create Surfaces
- Build Part
Use Import () to load point data from a file. Options will vary depending on the type of file being used.
In the case of STLs, it’s possible to automatically create meshes when importing. This is useful if you know the mesh has already been refined and is of good quality.
Refine Point Cloud
Quite often, the point clouds are very dense and contain more data than needed. Use commands such as Filter () and Remove () to reduce the number of points. This will help with general performance and can also lead to smoother, cleaner surfaces, especially when dealing with rough or less-than-ideal scans.
A mesh is built from the cloud of points. Mesh Creation () takes the current point cloud and converts it to a usable mesh. This mesh will be used in Quick Surface Construction to create surfaces.
Quite often, the generated mesh will have problems. These can be as simple as small holes that need to be filled, or they can range from triangles facing the wrong directions to inverted faces.
Typically, start with the Mesh Cleaner () and run it to fix major issues. This process may need to be repeated a few times.
If there are gaps in the mesh, Fill Holes () can be used to automatically fill these openings. Or, Interactive Triangle Creation () can be used to manually fill these gaps by hand-drawing needed triangles.
It is very important that the final mesh does not contain any deformities. If it does, it cannot be converted to a CATIA surface.
After creating the mesh, head to the Quick Surface Reconstruction workbench. The Automatic Surface () tool can be used to quickly generate a surface that matches the meshed shape from DSE. Depending on the end goal, this may be enough to get a usable surface. Other options include PowerFit (), used to adapt to surfaces within curves, or Basic Shapes
(), used to generate primitives such planes and cones around certain areas of the mesh to get more robust features. Curve and Surface Networks can be used to generate surfaces akin to a Multi-Section.
Alternatively, it may be easier to skip creating surfaces directly and instead, trace characteristic curves on the mesh with 3D Curves (). Then, using Generative Shape Design, create a high-quality CATIA surface from these curves.
In the image above, the top of the part primarily consisted of flat faces, which were built using Basic Shapes, ensuring the faces are completely flat, planar, and high-quality. The gear portion at the bottom of the part was converted to a surface with Automatic Surface.
Once the QSR surfaces have been created, these can be used in any of the standard CATIA part workbenches. You may need to Split/Trim/Fillet these individual surfaces to get a finalized shape. Above, the Basic Shapes were filleted and trimmed, then Joined with the Automatic Surfaces to create the final model skin.
Or, sometimes, simply take the automatic surface and make it into a solid using the Close Surface() in Part Design.
For this one, a solid was generated from the joined surface in the prior step. From here, any standard Part Design commands, such as Pad, Pocket, Hole, Chamfer, etc. could be used to modify, tweak, update or otherwise redesign this part.
The Big Picture
Whether you’re new to working with scanned data or just new to working with scanned data in CATIA, we’ve taken a look at the big-picture approach to this subject. Sometimes, the hardest part is figuring out which workbench to be in, which icons to use, or just plain simply where to start. Though there are finer details and more commands to be discovered, this knowledge should make for a good starting point in your scanned data/reverse-engineering endeavors.
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