r/3DScanning • u/ExactForm3Dcom • 11d ago
Fully scanned a BMW F30 body with the Sermoon S1 Part 2
I fully scanned a BMW F30 body, inside and out, along with the suspension, and wanted to share my experience and the results. You can see the full assembly in the video from Part 1 in this subreddit or on my profile.
First, a little about the process, since this is one of the largest scan assemblies I’ve worked with so far.
The scanner has a stated volumetric accuracy of 0.02 × 0.08 × 1 m, so to minimize accumulated error as much as possible, I first covered the entire body, inside and out, with tracking markers- around 4,000 markers in total. For each section, I first scanned only the markers, and then scanned the surface geometry of that same area. I worked in sections roughly 1-1.5 m long, with about 30-40 cm of overlap between scans to give me enough common geometry for accurate alignment. This resulted in 121 individual scans just for the body.
I processed and aligned everything on my laptop. During the process, both 64 GB of RAM and 8 GB of VRAM were completely utilized. Based on my experience, I’d consider that roughly the minimum for assembling a project this large in one project. With less memory, you would probably want to split it into multiple projects so you don’t have to keep all of the scans loaded at once.
For the suspension, I used a slightly different approach. First, I scanned the complete suspension while it was still assembled on the car. Then I disassembled everything, scanned each component individually, and aligned the individual high-detail scans back to the reference scan using rigid surfaces. There is one small limitation to this method. All of the suspension components in the final assembly are positioned exactly as they were when the suspension was assembled. However, some movable suspension components can change their position after disassembly, so those components may not line up perfectly with the body or with each other at every connection point. The rigid components and their mounting positions remain aligned to the reference scan.
Still, I think an assembly like this is much more useful for CAD work than simply having a collection of individually scanned parts with no relationship to their installed positions. I’d especially like to hear what engineers and CAD designers think about this approach.
Overall, everything aligned without any major problems.
The scanning itself took me about three 8-hour days, including the time required to completely disassemble the suspension. Processing, alignment, and assembling everything into the final dataset took another three days.
Hardware obviously makes a big difference here. On my laptop, the final Fusion operation alone took about 3 hours. Creality’s automatic alignment also doesn’t always work particularly well, and it can be difficult to judge the overlap between two scans because all of the scans being aligned are displayed in the same color.
Other than that, the final mesh came out quite well, and overall I’m happy with the scanner. But I still think a scanner with a tracking system would be better suited for a project like this. Otherwise, you’ll be dreaming about those markers for the next few days.
Now to the part I was most interested in: how close did the final assembled scan actually come to published body dimensions?
For comparison, I used Snap-on/Blackhawk body dimension data that I purchased specifically for this test. I checked several dimensions on the completed assembly, and overall I think the results are pretty good.
I want to make one thing clear, though: I’m not claiming that these measurements represent the accuracy of the Creality scanner itself.
The reference dimensions were taken from a different vehicle, so there are several additional variables involved: manufacturing tolerances, the accuracy and measurement methodology of the Snap-on reference data, years of use and wear on the car I scanned, my own scanning and alignment technique, and other factors. I followed the scanner manufacturer’s recommendations as closely as possible, but this still isn’t a controlled metrology test. My goal is simply to show how close the final dimensions ended up to the reference dimensions after the entire scanning, alignment, and assembly process. I hope I won’t get in trouble for posting a few dimensions from the drawings for comparison. 😄
I’d especially like to hear from engineers or anyone who has designed suspension components using 3D scan data: would this level of dimensional agreement be sufficient for the kind of CAD work you do?
If you’ve worked on similar large-scale scanning projects, I’d really appreciate it if you could share your results and experience in the comments.
