Reverse engineering is the process of discovering the technological principles of a device, object or system through an abductive analysis of its structure, function and operation.
As computer-aided design has become more popular, reverse engineering has become a viable method to create a 3D virtual model of an existing physical part for use in 3D CAD, CAM, CAE and other software. The reverse engineering process involves measuring an object and then reconstructing it as a 3D model. The physical object can be measured using 3D scanning technologies like CMMs, laser scanners, structured light digitizers or computed tomography. The measured data alone, usually represented as a point cloud, lacks topological information and is therefore often processed and modeled into a more usable format such as a triangular faced mesh, a set of NURBS surfaces or a CAD model.
A triangulated surface can be generated from the 3D volume CT reconstruction. The resolution of the 3D model depends on the number of voxels generated from CT reconstruction.
Typically models are composed of 50000 faces up to 10 millions faces.
About surface rendering
A threshold value of radiodensity is chosen by the operator (e.g. a level that corresponds to plastic). A threshold level is set, using edge detection image processing algorithms. From this, a 3-dimensional model can be constructed and displayed on screen. Multiple models can be constructed from various different thresholds, allowing different colors to represent each component of an assembly. However, the interior structure of each element is not visible in this mode of operation.
The 3D model can be exported to many different formats including Points Cloud or STL, compatible with most CAD software.
It’s then possible to load the 3D CT model into CAD software and perform measurements, model comparison or simulations.
There are numerous benefits to using CT as a Reverse Engineering tool. First and foremost the generated model is complete (no shaded zone) and has all internal information. Also, CT is faster than any other 3D technology, CMM or Laser scanning. Finally, the resolution is excellent and largely fulfils designer’s needs.