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Laser Scanners

Scott D. Haselden
I have used Romer arms with DMIS for a few years now, but never had one with a laser scanner before. I may have an opportunity to take on a new role in a facility that uses a scanner to do profiles on curved surfaces like car dashboards, etc. Id like to hear from anyone that may have used laser scanners before, before I toss my name in the hat. i don't want to leave a company where I am successful for a position that has some advantages, if I know my chances of success are low.

How are scanners different than a probe based romer? Are they much easier or more difficult to use? Do you have to import a Cad model to take measurements? If so, is it the same as programming in CAD, on a regular CMM? And finally, all the videos I have seen show an imported cad model being overshadowed by the cad being "painted' in the Graphic Display Window. Does the software automatically compare the profile of the produced part to the Cad model, or do you have to take traditional dimensions from the "painted surface", in the way that you would a standard part measured by touch probe? I know that the CAD is produced as you take touch points. I was wondering if the version of DMIS works the same with a laser scanner.


Does anyone have any links to more instructional videos, concerning using laser scanners?
  • You would really need training, nothing is really "automatic" and you can do a lot of interesting stuff with the laser scanner that just really isn't intuitive. There also isn't a whole lot of online tutorials since a lot of what you might encounter can be relatively specific to the application at hand. Sometimes you might be just creating a color map from a point cloud, other times you might need to generate features from scanned points. Understanding the point cloud and how to work with it and manipulate the data can be a bit overwhelming if you have no experience in the matter.
  • I have used Romer arms with DMIS for a few years now, but never had one with a laser scanner before. I may have an opportunity to take on a new role in a facility that uses a scanner to do profiles on curved surfaces like car dashboards, etc. Id like to hear from anyone that may have used laser scanners before, before I toss my name in the hat. i don't want to leave a company where I am successful for a position that has some advantages, if I know my chances of success are low.

    How are scanners different than a probe based romer?
     You've been using a hard probe to capture accurate points, very slowly. A laser scanner can be used to capture slightly less accurate points, extremely quickly. Think 100,000 points/sec. How long would it take to hardprobe enough points to define, say, a human face? Months? With a laser scanner, you can capture the data in 15 seconds.

    Are they much easier or more difficult to use?
     Depends on how well you understand the hardware/software. There's more involved. With a hard probe, all you care about is that your part and arm are firmly fixtured, and you can begin probing/programming. With a laser scanner, you don't touch the part, so it doesn't NEED to be fixtured. However, now you have to worry about noise/surface condition/reflectivity, and a host of other issues that don't arise with hard probing.

    Do you have to import a Cad model to take measurements?
     Doggone hard without it, but it can be done. I almost never bother.

    If so, is it the same as programming in CAD, on a regular CMM?
     in PCDMIS, there is a feature called a CoP (cloud of points). It's the features that holds the mass of scan data you generate. You can either generate autofeatures from the CoP, or alter it directly (filter it? remove some of it? colormap it vs the CAD?) with special CoPOperators.

    And finally, all the videos I have seen show an imported cad model being overshadowed by the cad being "painted' in the Graphic Display Window. Does the software automatically compare the profile of the produced part to the Cad model, or do you have to take traditional dimensions from the "painted surface", in the way that you would a standard part measured by touch probe?
     No, you basically have to use the CoPOperator to generate the equivalent of a Profile Dimension

    I know that the CAD is produced as you take touch points. I was wondering if the version of DMIS works the same with a laser scanner.
     PCDMIS doesn't generate CAD.


    Does anyone have any links to more instructional videos, concerning using laser scanners?
     Google and YouTube!
  • in reply to Colin Simithraaratchy
    very informative, thanks. I was fortunate enough to sit down with a hexagon engineer at the South Tec Conference this past week, and they helped me understad a lot of the differences and the similarities between what I am accustomed to and using the scanner. they also showed me a lot of techniques and tricks of using the scanner, so that was very helpful. thannk you very much for taking the time to reply as thoroughly as you did.
  • While the scanning functions in PC-DMIS aren't the best out there, they are easy to use and can be figured out by spending a few days playing around with it. I wouldn't let it be a deal breaker if you can improve your situation.
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