Precision 3D scanning with GOM scanner

2019-03-01

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Technologies used:

  • 3D Scanning
  • GOM
  • MeshMixer
  • MeshLab
A 3D Scan of a David statue made with a GOM Scanner

Introduction

The piece that we started with is a scale model of David statue, we wanted to scan this model as a practice on how 3D scanning can be a great tool in design.

The equipment we had available to do the task is a Gom Scanner Atos Core which is a high precision 3D scanner that uses photogrammetry techniques to obtain detailed models of small objects.

Calibration

The scanner comes with a calibration piece that is stored in a heavy duty briefcase for protection.

The calibration tool is a white piece with holes which is placed on the scanner bed, the software in the scanner will then use this piece as a reference for measurements.

Calibration plate for the GOM Scanner

The software also asks for a temperature measurement of the bed, for which we used a thermometer.

Taking a temperature measurement of the calibration plate

Once we input the temperature, the software will guide us on how to move the bed with the calibration tool.

Moving the calibration plate

You only need to follow the movements indicated

Software steps to calibrate the scanner

When we complete the set of instructions the software provides, we will receive a window with the calibration confirmation, as the below picture shows.

Calibration success popup

Scanning

After calibration of the scanner, we proceed to prepare the piece to scan. For this task a set of stickers were placed on the piece which the software uses as reference when rotating the piece on the scanning bed.

Tracking markers for the piece to be scanned

You need to put enough sticker so that the scanner can always see at least 3 markers.

Model of David statue with tracking markers

We then proceed to fix the piece to the scanning bed using bluetack.

Then using the software, we started to capture geometry by taking pictures of different positions as we move and rotate the piece around.

Scanning the model with the GOM Scanner

Cleaning the scan

The file received to be processed was in the format of .stl file, which can be open and manipulated in several software tools. In our case we are interested in cleaning, combining and turning into a solid two separate pieces that we received by scanning a miniature statue of a David.

The software that we choose to use waa meshlab and meshmixer wich you are available as a free download, we use meshmixer because it offers an easy way of moving the scan around and also cleaning the parts that we don't need, while meshlab will be used to patch the parts of the scan that might be missing.

Meshmixer

The scans received consisted of two .stl files that were the front and back part of the statue, this files had some cleaning since they had scans from the bluetack used to secure the piece to the bed, other than that the files were detailed and clean. In the next picture we can see one of the scans obtained.

3D Scan imported into MeshMixer

In order to align the two parts correctly the transform tool was used which allows us to rotate, scale and translate the scan.

Aligning the 3D Scan in MeshMixer

In order to clean each part we use the selection lazo tool which allows us to select a surface by drawing a circle around it.

Cleaning the scan with MeshMixer

Then once you have the piece selected you can hit edit -> Discard or it's hot key x.

Combining the scan with MeshMixer

The next step consist in combining the two halves of the statue, which is done by using the Union tool that appears when you select the two scans.

Combining the scan with MeshMixer

Once we had a single file, we proceeded two export it as an .ply file, which can be further manipulated in Mesh lab in order to close the gaps in the scans.

Meshlab

We use Meshlab to patch the surfaces that the scanner wasn't able to acquire.

3D model imported into meshlab for cleaning

Once we imported the .ply file into Meshlab we proceeded to use the screened poisson surface reconstruction tool that can be found under the filters -> Remeshing, Simplification and reconstruction, with its default settings.

Patched model of the david statue in MeshLab

After the computer handles the calculations, we obtain a pretty good surface, where the newly generated surfaces integrate to the scanned ones. Next we save the file as both .ply and .stl to further use it in other applications like 3D printing. The next images show the finished scan in more detail.

Final 3D Scan front Final 3D Scan side