One of the largest and misunderstood challenges people encounter when converting physical objects to digital is a major incompatibility between two different types of 3D models: 

 

Scanner output = meshes(.stl/.obj) and CAD output = solids(.STEP/.IGES or any native CAD).

Scanner output = difficult to edit or machine                       CAD model = Easily modifiable or machinable

 

The most common processed output for both commercial and consumer 3D scanners is the .STL file format, and it's also the format that is used by 3D printers. This makes creating a 3D print from a 3D scan very easy if that is the goal for the 3D scan. However, that is not always the case. An .STL files is composed of many points in space that create triangles, the triangles, then connected, create the surface of the object being scanned. A Mesh model does not contain feature or size information about the object other than the position of the points/triangles that define the overall component. Some larger scans contain many millions of point and triangles, making editing or viewing in some CAD programs unfeasible.

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If the end goal is to make major modifications or design changes to the scanned part, the 3D scan will have to be converted to a solid CAD model, this is where reverse engineering by Northeast 3D bridges the gap from scan to CAD.

 

There are 3 common ways to achieve this:

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• Full Reverse Engineering

  • The goal of full reverse engineering create an end use 3-D model, which can be a near exact replica of any given physical component. This process is used for a wide range of applications – from prototyping to reproducing and scaling artwork. This is ideal for complex parts or parts that need to be recreated in traditional CAD software for the purpose of producing a parametric model based design.

• Hybrid Reverse Engineering

  • A hybrid model will contain characteristics of both a Feature Based Model as well as a Rapid Surface Model.  It is developed using a variety of techniques in order to develop a model that has both mechanical as well as free-form or organic geometric features.

• Wrapped Surface model

  • A wrapped surface model is developed using a “blanket” of surface patches that are “shrink-wrapped” onto the .STL file to create a model suitable for import into CAD. When viewed in CAD the surfaces are similar looking to an STL file but they are stitched together to form a non-parametric solid model. Rapid surface models are useful for highly complex shapes such as organic forms, art & sculpture or intricate castings. 

 

Hybrid modeling used to repair broken bracket in preparation for printing.