This past week I got my hands on one of Creaform’s latest scanners the GoScan! 50. This white-light scanner is designed for “medium to large” sized objects and scans while collecting RGB data in order to produce a photorealistic mesh. Scanning is controlled and registered via Creaform’s VXelements software suite which is included with the scanner. The GoScan! 50 measures at 550,000 measurements/sec at a resolution of 0.020 in. (0.500mm) and an accuracy of 0.004 in. (0.300mm).
Test Applications
I started off with small objects around the office (coffee cup, computer keyboard, etc.) I then moved on to more organic shapes (mostly toys my kids have, like an Incredible Hulk action figure and some model aircraft). Lastly, I used it on some pipe sections varying from 1 inch (25.4mm) OD to 42 inch (1.06m) OD in size.
Scanning
To scan, you have to connect the GoScan! 50 to AC power and a laptop running Creaform’s VXelements software suite. Next, you calibrate the scanner using a provided calibration plate (normally takes < 1 minute) and you are ready to go.
The scanning works using two methodologies: natural feature dependent or target dependent. While the natural features option is very handy, it does have some limitations. The object you’re scanning will need to have unique geometry and/or color variation within the 15 in X 15 in (38cm X 38cm) field of view in order for this methodology to be successful. Additionally, you may have problems if you have the same feature repeated in multiple areas.
For target-dependent scanning, you place small adhesive dots on or around the surface being scanned. While this allows you to scan things that offer less geometrics variation (like a flat surface), it does take a bit of time to place the stickers at the recommended 0.75-4 in (20-100mm) spacing and then remove them after scanning. The fact that they cost about 10¢ a piece seems a bit problematic as well when you start trying to cover a 42 inch OD pipe.
For the most part, you scan and the data pops up on the screen. If the light on the scanner stays green, you are registering and everything is fine. Red lights tell you that you are too close to the object, too far from the object, or that you have lost your lock and the scanner no longer knows where it is. If you lose lock, you simply go back to an area that you have already successfully scanned and the scanner should regain lock. The real-time visuals enable you to make sure that you have full coverage and that you are registering correctly–especially if you are using natural features as constraints.
Data Processing
There are not many things built into VXelements when it comes to the basic package. However, there are additional add-on modules, including Scan to CAD which aids in producing CAD models from the scan data, and VXinspect which allows users to compare a CAD model to the scanned data. I could write an entire column on the Scan to CAD module (and may) but for now I will concentrate on the sections of the software related to scanning and data export.
You can select and delete erroneous data and targets after the fact. You can also delete previously collected frames while in Scan mode. Exporting is basically limited to mesh export which is a bit of a disappointment–as the last Creaform I used also allowed for the export of point cloud data. The only way I was able to convert the data to point cloud was by importing the mesh into CloudCompare and then exporting a grid sample. It was accurate and quite dense but it took a bit of time to get there.
Results
On the small stuff I was incredibly impressed. The scanning was fast, the processing was fast, and the results were print-ready watertight meshes (with very good RGB values) in under an hour.
As things got larger the difficulties began. Let me first say that the manufacture’s guidance for the intended use was a bit vague. “Medium to large sized scan projects” to me is something less than a General Motors assembly plant. I get the feeling that to Creaform, the size object they mean is closer to what you could fit in the overhead bin of an aircraft. While the scanner seems capable of handling larger things, the software starts to hit a wall.
First of all, your project is stored in your laptops RAM while scanning. I immediately ran into issues here, as I only had 16GB of RAM. I added more sticks and at 32GB, I never ran out of space again. However, simple processes like saving, or updating a surface for a larger object took a very long time to complete. For example, when I deleted some frames that were registered in the wrong place, it took 6 hours to update the surface on a project that was less than 2GB in total size! That, “Am I going to be done for the day if I hit this command” mentality started taking a toll on us by the end of the week.
Cable management also became an issue on the bigger jobs. Essentially you are holding a hand scanner that is tethered to an AC outlet and a laptop (that is also tethered to an AC outlet) and if anything comes unplugged you may be in an hours-long save mode to get back up and running. Essentially, I started viewing any job outside of a lab situation as a two-man job. The second set of hands doesn’t need to be trained as a scanner as much as a gaffer. We also experienced some registration errors on the 42-inch OD pipe. Essentially, it would use flange bolts as natural feature constraints and occasionally, it would simply choose the wrong bolt(s). We were able to overcome this by turning off the “use natural features” tab and relying solely on targets for constraints.
Conclusions
For most things I found the GoScan! 50 to be exceptionally useful and quite practical for capturing items for inspection, 3D visualization, and reverse engineering. We did have some issues with larger objects but as I said, it had more to do with an inability to accurately judge the time necessary to process the data than anything else. I’ll be checking in with Creaform this week and hopefully find that there are some settings on my hardware that will remedy this. One of the most impressive takeaways from this was the reaction I received from clients that have seen the data captured by the GoScan!. It is beautiful and exceptionally clean when compared to most tripod based point cloud data that we are all accustomed to seeing.
When you need submillimeter accuracy and resolution the GoScan! 50 is definitely hard to beat.
