First Scan – Cessna 172 Nosebowl

After playing around with the EXAscan for the past few days, I feel like I’ve got the hang of it.  There is certainly a bit of a learning curve when transitioning from a mechanical arm to a laser scanning one, but overall I found it took me far less time to get up to speed with the EXAscan than it did with the FARO.  I decided to use my Cessna 172 as a test case, and scanned the cowling nose bowl.  That’s one of those tasks that I really dreaded with the mechanical arm, and boy what a difference it makes to do it this way.  Here is the final scan in VXelements, which is the software used to interface with the scanner:

The classic rookie mistake with these devices seems to be to set the resolution very high, but for surfaces like this, there’s no need to take all that much data.  I do most of my work in inches, and in this case set the resolution to 0.1″.  I thought that would be way too coarse, but as you can see there is plenty of data there from which to build my model.  Here’s what the unit looks like in action, you can see that it’s quite small:

Here’s how the .stl file looks once it’s imported into Rhino – no surprise here, it looks exactly like the VXelements rendering:

Overall I’m over the moon for this thing.  Love, love, love it!  Soon I will show you my process for taking this .stl mesh and making a very nice watertight NURBS surface.  I think you’ll be pretty amazed……

Comments
2 Responses to “First Scan – Cessna 172 Nosebowl”
  1. Harry says:

    That’s certainly a compact little rig….it’s funny how used to “precision” we get now that we have access to digital everything…I wonder if Cessna had a 0.1″ tolerance on their nosebowl specs!!

    Is VXelements the proprietary s/w that goes with the scanner? Or is it some 3rd party suite that is necessry to get it ready for Rhino?

    You’ll probably be scanning everything in sight!

    • Harry –

      What’s important to remember is that resolution and accuracy are independent of each other. The accuracy of the scanned mesh is determined by the size of the part. The resolution is simply how much data the unit collects to stitch together a mesh – the density of that mesh. It took me a bit to realize that by turning up the resolution, you weren’t getting better data, just more of it. Really the sweet spot is to find just barely enough data to get the job done. I could probably bump the resolution up to 0.2″ and still get a fantastic mesh.

      VXelements is strictly used to interface with the scanner. It’s relatively simple, especially if you have any CAD experience, and that’s one of the things I really like about it. Very intuitive, enough features to do what you need it to do, but not so much extra stuff that it’s difficult to learn. That was one of the things I was turned off by with the new FARO products – there is simply a dizzying array of software available for both scanning and processing, but for me what I just want is to scan a surface and then work on it in Rhino.

      Just got back from a scanning job, and have three more booked for next week, so yes, trying to scan as much as I possibly can!

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