Designing from the Outside In: Reverse Engineering

Product design today is largely a digital effort. Paperless design has been something that writers and analysts in the industry have been writing about for years, but the reality is that though designs can be tested, verified and validated digitally, physical parts and prototypes remain a reality for most manufacturers.

As a result, capturing data from physical objects and putting that data back into the digital model is often a crucial part of the design cycle.  With the use of 3D CAD systems on the increase, reverse engineering has become a practical tool to create a 3D virtual model of an existing physical part that can then be used in 3D CAD, computer-aided manufacturing and other computer-aided engineering applications.

More manufacturers are adding reverse engineering to their product development efforts, in part, because the costs of the scanners and other hardware used to input measurements have dropped dramatically in price. At the same time the hardware has gotten smaller and easier to use. The software has also become easier to use and the process of converting and managing scanned data simplified.

The reverse engineering process requires hardware and software that works together; the hardware is used to measure the object and the software reconstructs it into a 3D model. The physical object can be measured using 3D scanning technologies, such as coordinate measuring machines (CMM), laser scanners, structured light digitizers or computed tomography.

Let’s take a look at some of the advancements in reverse engineering technology, from the 3D laser scanners to the software that helps convert the scan data.

Scanning new advancements

A growing number of engineers are using laser scanners to help create prototypes for new products and ensure their conformity to original CAD designs. Even when prototypes are produced using the latest and most accurate methods, they still often need to be measured and checked against CAD designs to ensure accuracy for the customer. Laser scanners make it easier to capture 3D data from physical objects.

New 3D laser video scanners capture a 3D image in each frame and then combine them automatically into a single mesh. The scanning process enables users to walk around the object while continuously videoing it from 360 degrees. The video-based scanners measure speeds of up to 500,000 points per second, making them faster than laser scanners and are able to scan moving objects as well as stationary ones. Because they are portable, they can be used for sports, medical, computer graphics, architecture, prototyping and manufacturing applications.

Traditionally scanners required multiple setups and fixed-position tripods, mechanical arms or external positioning devices that must be aimed at re-aimed at the target surfaces. New handheld scanners can digitize 3D surfaces in real time and capture surface information in full 24-bit color, rendering the complete picture of the object, not just the geometry.

These handheld models are ideal for scanning objects in tight spaces. Also, they capture data in a single reference model so users don’t have to invest the time or risk errors post-processing to stitch multiple scans into one. Color 3D data enables more realistic and data-rich visualization and concept models, making it perfect for product design and reverse engineering.

On the soft side

Several improvements on the software side have also made the process of reverse engineering easier and faster.  The result of scanning a physical object is a point cloud of data, which is often enormous in size. With previous versions of reverse engineering or point cloud processing software, users would then weave surfaces through those point clouds, continually tweaking the accuracy and fit. The result was a model with no features, parameters or intelligence, just geometry.

Today, reverse engineering software is now easier to use and more affordable than ever. It’s also tightly integrated with CAD programs so engineers can access the most important features through their CAD software. Users can scan objects and then import the scanned data into reverse engineering software. The software processes the 3D point could data and then convert it into a model, a neutral, surface-based CAD model or a mesh that can be simulated digitally.

When further optimization is required, however, these models often lack the intelligence or design intent from which to make further refinements and changes. The wider adoption of direct modeling tools could change that. Direct modeling capabilities enable designers to direct manipulate model geometry without regard to its history, making it much easier to manipulate and tweak surface-based models created with scanned data.

Image by Paolo Tonon

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