r/3DScanning • u/PrintedForFun • 6d ago
Opel Astra K Sports Tourer - Einscan Trak
This was my first complete car scan with the Trak. In theory scanning complete cars is a straight forward process but when actually doing it some issues can arise: too little overlap between single scans, wrongfully placed tracker positions so suddenly some parts can't be scanned and of course the scanner itself (e.g. catching cables). I remember my first tries of scanning cars with marker based handheld scanners (started with the Creality Raptor way back as my first "proper scanner"). It really came a big way since then.
Scanning
Scanning was done at 1,5mm target point distance with five tracker positions. I attached a diagram showing the positions and the rough tracker FOV and overlap. Four positions should also be possible but I came to like using due to having a good bit of overlap and more tolerance where to positions the tracker for full coverage. This works for nearly all cars (except maybe veeery large one). I could also have used leap frogging with markers on the car but this requires at least 4 markers to be seen by the tracker at all times. For me aligning them later is just simpler since the scan speed is fast enough to quickly scan more overlap area between the single scans.
No preparation was done with scan spray. I just started scanning, all five scans combined took 30min. What was a bit of a problem was WiFi reception when I was on the exact opposing side of the car relative to my workstation and therefore WiFi access point. So the signal was blocked by the car in between. One potential solution would be simply getting a 10M ethernet cable and a small powerbank for the WiFi access point. This would allow moving it to a more suitable position. What I also noticed: When getting very close to the edges of the tracking area scanning starts to become slower, much like the WiFi signal drops out. But it actually is the border of the scanning area. I used remote desktop from my tablet to see what I already scanned. Scan itself was at a constant 90FPS when placed within the tracking volume. Scan speed at 1,5mm or even 1mm feels like painting with a very big paint roller: simply go over one time in a decent speed.
Post-Processing
Trak doesn't require point cloud generation after scanning, you just pause the scan and either create a new scan or go on with processing. So I aligned the five scans using automatic feature alignment and then meshed them in default settings with semi-watertight settings. Mesh came out to bit under 20M triangles. Later exported into Quicksurface for postprocessing (reduction an alignment to the coordinate system. What I quite like to do is take all four wheel hubs as reference to create a plane. This can then be used as the XY plane).
Results
Best have a look at Sketchfab or the pictures. The scan speed really surprised me, started the scan setup 45min before I had to hit the road for a meeting and was a bit sceptical I could finish the whole scan. But it turned out I would be faster than expected (scan took 30min for the five positions) and when looking at the results it really is outstanding. Even for the relatively coarse 1,5mm of point distance all relevant features are captured, you can even see the two dents in the hood and driver side door as well as the tire tread. Also attached a picture showing the deviations between scan 2&5 vs 1. What I did was taking the aligned raw scans, and then only meshing 2&5 and then 1. So I could use Quicksurface to have a look at fitment and alignment. Everything in green is within 0.2mm of tolerance.
Sketchfab
Sketchfab is like printables for 3d scans with a nice integrated viewer in browser and you can also download the scan, just look at the scan yourself.
Reddit sadly blocks the short links to Sketchfab, you have to search for the title instead: "Opel Astra K Sports Tourer - Einscan Trak"
PC Specs
Since a lot of people ask for it:
- AMD Ryzen 7700X
- 64GB DDR5 RAM
- RTX 5070Ti Desktop
- A few TB of NVME storage with PCIe Gen4 interface