Bathing in Blue Light

NPC uses blue light 3d scanning to preserve a piece of the past.

Victoria Russman
Victoria Russman
Vintage 1920's bathtub

It may look plain, but this is no ordinary bathtub. This is a vintage, cast-iron tub installed in a Chicago high-rise apartment in the 1920’s. It withstood the test of time. They don’t make tubs quite like this anymore. NPC is on a mission to preserve the past. We are helping a customer gather important data they will need to manufacture these calming casks. We can measure different object sizes, surface finishes, and shape complexities utilizing structured light 3d scanning. Here, Design Engineer, Chad uses the ATOS Q blue light scanner to digitally capture the tub’s exact size and shape. Before we get to the final deliverable there are steps we need to achieve for success on this unique blue light scanning project.

Step 1: Calibrate

Let’s walk you through what it takes to scan a part of this size while on location in, of all places, a bathroom! The first step is to calibrate the blue light scanner. We do this because we have to change out the two lenses. The lenses are used to capture the data much like a camera lens. For this project we use a 350mm measuring volume which equates to the field of view of the lenses. The calibration process can take an hour to an hour and a half. To save time, we do this before arriving on location.

Calibrated stickers for blue light scanning

Step 2: The Stickers

Up next, Chad adheres tiny, calibrated stickers all over the surface of the tub. He uses tweezers to handle the small dots. They are delicate and he has to be careful not to damage them. The stickers are calibrated to an exact size and thickness. As one can imagine, this part of the process is time consuming due to the size of the object and number of stickers needed to cover the area being scanned. We use these stickers because each scan is made up of several sub-scans. Using the stickers enables us to triangulate the areas and stitch the scans together seamlessly.

Structured light, blue light scanning a bathtub

Step 3: Scanning

It takes about 75 scans all the way around the tub to complete the task. This is completed in approximately two hours. There are some challenges along the way, including shiny fixtures. These have the potential to affect the quality of the 3d scans. To combat this, Chad uses a special 3d scanning spray made by AESUB. We use it on the reflective surfaces of the fixtures and drain. It can be applied on any surface either reflecting or transparent and sublimes within four hours. It has a powdery texture to it and enables the scanner to pick up shiny surfaces with better accuracy.

Step 4: Post-Scan Processing

Once the scanning is complete, Chad heads back to the office. There is collection of data and post-scan processing to be completed. He uses software created by GOM to perform this task. There is a transformation process where the data is stitched together to make one single scan file. The software also knows to subtract the stickers because of the diameter and thickness we discussed earlier. The final deliverable is a point cloud of the data in STL format.

Not a typical job, but fun to get out of the office and spend the day... in a bathroom?!?!

If you have a project that would be suitable for structured light 3d scanning, contact Nel PreTech today!

Seeing Is Better
Than Believing!

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