CAD import / export and reconstruction...

Reverse engineering software

The polygonal mesh modeling of 3DReshaper® generates models, made up with hundreds or thousands of non- continuous triangles.

These 3D meshed models are ready for rapid prototyping, tool path generation, simulation, analysis, etc.

However sometimes, a “continuous” model is required by CAD-CAM software. This process of making a CAD model is also called “reverse-engineering” because you generate a continuous model, also called “exact model” from scattered data sets: mesh and point cloud.

This module allows you to make CAD Surface reconstruction starting from a mesh. CAD Surface means NURBS and BSpline surfaces that are fitted on your original mesh. Finally, these surfaces could be exported into IGES or STEP file and/or used to make inspections.

Nurbs Surfaces

To reconstruct in 3DReshaper a CAD model from a scan data, you will be able to:

• create a polyline network with few rules to follow in order to delineate the future surface patches.
• take advantage of the automatic and manual functions for creating and editing your polyline network.
• automatically compute the BSpline curves from the previous lines.
• adjust all or part of the polylines and BSpline curves at any time.
• compute NURBS surfaces.
• locally improve the result if necessary (new patch creation, surface continuity, hole creation within a patch...).
• export the CAD data and make a surface compound in case of 3D inspection.

CAD import (IGES-STEP)

The most common use of IGES and STEP import is to perform inspection; i.e. the comparison of reference geometry with an as built geometry (2 and only 2 entities: the reference geometry and the other object). Then, you MUST insure that your reference is a unique object, which is often not the case after the import command.

Some rules are very important to remember:

• If you have used the option "try to sew" and you have obtained one object, you are 100% sure that you can directly use this object for inspection.
• If you have poor quality geometry, so that it is not possible to quickly make a correct surface, it is possible to only group all the surface pieces into a compound mesh using the appropriate command.
• To obtain good inspection results, it is necessary to have all the surface pieces having the same normal orientation.
• It is also necessary to have NO duplicated surface. Unfortunately, some CAD software provide files with duplicated surfaces. This is not really a problem on the CAD side but on the inspection side some of the points are projected on one of the surface while other points are projected on the other.

3DReshaper enables you to quickly import and prepare if necessary the CAD models.

With the NURBS reconstruction module, the import of CAD surfaces is very fast. The mathematical definition of the CAD model is preserved.

Note that if you do not have the "CAD modeler base" license, you will be still able to import CAD objects but the Iges and Step export will be not possible.

3DReshaper offers all necessary tools to handle, reconstruct or improve typical CAD objects.

 

Point cloud coming from a scanned hull

 

3D mesh with a designed network of polylines

 

BSpline curves creation

Nurbs surface patches generation

 

Import or surface compound of a CAD model in the frame of a 3D inspection