Surface models are ready for design, simulation and manufacturing applications.

A reverse engineering project starts with a 3D scan of an object. A laser scan returns a point cloud that can roughly resemble the object—if you squint. It requires the mind to connect the dots to “see” the object, not unlike seeing Orion—or his belt—in the stars. Luckily, we have apps for that. There are applications that connect the dots for you, creating a mesh of triangles, each a surface, and assemble a faceted surface approximation of the object. The more sophisticated applications will create smooth surfaces, fitting splines through the points and a smooth surface through the splines.
One of these sophisticated applications is PolyWorks Modeler by InnovMetric, which has released a major update for 2021. PolyWorks Modeler joins a class of point-processing, surface producing applications including Polygonica and, perhaps the best known in its class, Geomagic Design X.
Not only do surface models, such as those from PolyWorks Modeler, look more realistic, they are also far more compact (a smaller file size), easier to manipulate and usable for design and simulation as well as downstream applications, like CAM, for manufacturing.
How PolyWorks Modeler Can Help
Triangular meshes are not always perfectly formed. They can have gaps where a triangular surface should be. The human eye cannot discern a gap from a surface in a triangle—but PolyWorks Modeler can, and it will fill in the missing surface, making the mesh “watertight.” PolyWorks Modeler will also perform sketching on the mesh and building of additional geometry, with operations such as extruding, offsetting, filleting and Boolean operations (add and subtract).
PolyWorks Modeler intends to make a “CAD-friendly” model using NURBS-based surfaces that can be imported into design applications. You can extract curves from it or from the intersections with it. You can smoothly join surfaces with four-sided and N-sided patches. As point clouds can be “noisy,” PolyWorks Modeler can assist by finding the best fit through the points.
PolyWorks Modeler does not automatically create a solid model from a point cloud but does have a toolbox to help you create the solid model. You start using or creating planar geometry from the surface that will work as profiles for sketches. The geometry can be edges of slices of the surface or the whole surface. The profiles can be modified with additional 2D geometry (arcs, lines, circles and splines). And as with any solid modeler, the profile can be used with solid modeling operations such as extrude, revolve, sweep and loft to build a solid. The solid can be imported into any CAD program from the big four CAD vendors—SOLIDWORKS, CATIA, NX and Inventor and Creo.
What’s New with v2021
The big reason to upgrade to PolyWorks Modeler 2021 is that it allows you to get a full surface model of your part automatically. One click on a faceted mesh surface and the whole mesh surface is instantly recreated with a smooth NURBS-based surface—ready for your design, simulation or manufacturing application. If PolyWorks Modeler didn’t get it quite right in spots, the 2021 version has a retooled surface modification tool bar that lets you change it. You can add, delete or pull the existing splines this way or that so that they conform better to the scanned object—or to create a different version of the object.
PolyWorks Modeler v2021 lets you shortcut the reverse engineering process by scanning or modeling half the object and using a symmetry plane to create the other half.


PolyWorks Software in Use

Detroit-area Pratt & Miller Engineering provides automotive clients with engineering and low-volume manufacturing. Clients include GM’s Corvette and Cadillac CTS-V teams, which have won multiple racing victories. Pratt & Miller uses the PolyWorks product line to help reverse engineer its car components into CAD software.
Pratt & Miller provides many automotive design, engineering, fabrication, and race program management services. The company also does vehicle kinematic analysis, compliance testing, seven-post ride analysis, wind tunnel testing and development and vehicle dynamics and evaluation testing.
The company used to have its technicians build a 3D computer model from individual data points, fitting curves manually to the points to match curved body parts.
“That was an extremely time-consuming process and it didn’t give us the precision and accuracy we needed,” said Blair Sonnen, a Pratt & Miller engineer. “If we had to redesign a part to improve its performance, we would have to build another model the same way. In order to reduce the time spent in this process, and improve accuracy, we would sometimes hire an external company to come in and collect dimensional data using the scanning process, or to create curved surfaces from the discrete point data we collected. It was not a cost-effective way of creating models.”
Now it does 3D laser scans and uses PolyWorks Modeler to create the surface models that are read into CAD program. This method has been used for its GT-1 champion Corvette Racing Team, which is run in conjunction with General Motors.
Engineers create a clay model of a part, which is scanned with InnovMetric software and a FARO Platinum Arm equipped with a laser scanner. InnovMetric software is used for a best-fit alignment of multiple scanning paths.
For a whole car, many surface models are combined. Pratt & Miller uses the InnovWorks IMEdit application to fit the surface models together, nipping, tucking and filling as needed to produce a smooth assembly. Then, PolyWorks Modeler is used to make a class A surface model that is ready to be imported into Siemens NX, the company’s CAD program.
The CAD model is used for CFD simulation to analyze external aerodynamics and is used by ADAMS for dynamic analysis in a racetrack simulation.
Pratt & Miller’s Corvette Racing Team has scored successive championships in the American Le Mans Series as well as finishes in the Rolex 24 Hours at Daytona and the 24 Hours of Le Mans.

About InnovMetric
A Quebec City-based firm, InnovMetric specializes in 3D measurement software. The company was founded in 1994 and is best known for PolyWorks Inspector, which performs 3D dimensional analysis and quality control. The PolyWorks product line also includes IMAlign, IMEdit Reviewer, ReportLoop, Talisman, AR, DataLoop, PMI+Loop as well as PolyWorks Modeler (reviewed here).