One of our customer runs CFD Analysis on Boats. The software is using provides STL outputs. A STL model is a lightweight representation that only contains triangles. It is mainly used for 3D printing and also by some 3Dviewer.

Our customer contacted us because he needed to transform his scan into a surface. This article will explain you how we can transform a scan into a surface using automatic feature in CATIA.

Analyzing the data

Our customer sent us a model that directly from a CFD Analysis. The model is representing waves generated by a boat in motion. With a quick check using Digitized Shape Preparation application, we could see that half of the model contains a massive amount of triangles (600,000).


Half of the model contains 606,566 triangles.

If a scan contains a lot of triangles, it can takes time for your machine to work on the model but the result obtained will be more accurate.

We could also run a quick curvature mapping analysis on the scan to see where are the sensitive area to convert into a surface.


Curvature mapping on the scan.

Triangles to surface using automation

With the feature Automatic Surface   feature  that you can find the the Digitized Shape to Surface application, you can automatically transform a scan into a surface.

Before using this feature, be aware that if the topology is too complex (very high deviation for instance), the software will not proceed to the operation. However it is still possible to split the scan into several domains, apply the automatic surface on each domain then merge all the surfaces together using Generative Shape Design.

Using the automatic surface feature allows you to modify some parameters:

  • The mean surface deviation: If the value is low, then the surface will be sharp. In opposite the higher the value is the smoother the surface is. the software reach a limit if the value is too high, the result will be the same.
  • The surface detail: The parameter influence the number of patches the surface will be composed. The surface is more accurate with a higher number of patch, but it will take more time to compute.

Difference between the automatic surface’ parameters.

In this following video you can watch the full process of transforming the scan into a surface using the automatic surface feature. You will also see how to analyze the data at the beginning but also analyze the result obtain with the feature.

You can see the difference between a low quality surface and a more accurate surface. Of course you have to accept a small deviation tolerance from the original data.

You will also learn how to change the environment using Rendering Scene Design and observe the quality of the surface watching the light reflection.

Some operation are made in GSD to make a symmetry and merge the surface together using the blend feature.

You can watch the full design process on this following video.


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