Scanning & Digitizing

An important consideration when capturing point data is accuracy. The greater the accuracy, the bigger the file size. This obviously has an impact on the usability of the file. The key is to get data that are “accurate enough”— something best achieved through experience and through fully understanding the project. For example, there is a big difference between scanning a bathtub and a thumb!

Another critical step is to determine the number of scans necessary to capture the whole part. With Action Man’s head, for example, we had to make several scans to ensure that we fully captured the geometry of such features as the top of the head, behind the ears, and under the chin. Obviously, minimizing the number of segments makes the process simpler and faster.

Importing Scanned Data

Scanned data can be taken into Pro/ENGINEER as points, curves, or surfaces. Usually, the best approach is to create a point cloud file (usually a .pts format) from the scan and import it into Pro/ENGINEER as either points or datum curves. You can easily move or delete points, and then create datum curves through sets of points as required. We actually converted the points file from a .txt or .pts format into a .ibl format, which creates datum curves automatically. You can also use standard Pro/ENGINEER functionality to smooth the curves.

The curves can then be used to create surfaces in Pro/ENGINEER using standard boundary surfaces options. Control points are particularly useful to manipulate the surface, usually to make it smooth, as required. Although IGES creates large, highly complex surface files, it is still the best method for capturing complex details (such as hair) or textures (such as leather).

We did consider using Pro/SCANTOOLS ® (which can read point clouds and create curves at different pitches and orientations), but this process takes more steps than our preferred approach. It also requires careful control of the curves selected for surfacing.

What We Learned

During our Action Man project, we discovered that the most difficult—and certainly the most time-consuming— part is piecing together multiple complex surfaces to form a complete part. We found that the following techniques helped to speed this process:

1. To join the separate point cloud files, stick pins in the part as references. You can then use these points to join the sections, and later remove or patch over any “marks” from the pins.
2. Assemble the separate surfaces using offset coordinate systems to aid with translation and rotation.
3. Outline datum curves, showing the extremities of the part.