this is what we need to be working toward :) http://www.faro.com/en-us/products/metrology/measuring-arm-faro-scanarm/overview
On Wed, Jun 12, 2013 at 7:53 AM, jeremy youngs <[email protected]> wrote: > sorry sent before finished , i agree with all of the other statements > though > > > > On Wed, Jun 12, 2013 at 8:52 AM, jeremy youngs <[email protected]> > wrote: > > > ted said > > > > Even if it did, one would have to scan a "known-good-master" at each > > step of the production for the test scan to reference against. If you > > want accuracy, measuring scale on a single volumetric scan is near > > impossible. You need to have many angles and views stitched together to > > see past obstructions. Any imperfection in the part, including > > unintended, is recorded [perfectly]. > > > > > > not exactly just compare it to an iges file that will never change . or > > other parametric solid > > > > > > On Wed, Jun 12, 2013 at 8:44 AM, Ted Hyde <[email protected]> wrote: > > > >> In regards to a depth sensor, there's a good change Aram is referring to > >> a Kinect or the Asus Xtion (Pro Live). There's been plenty of > >> hacker-friendly attempts for "point-n-shoot" capture solutions using > >> these over the years, adding to the laser-line, and distributed-light > >> methods. The Xtion unit retails sub-$250, so it's an expensive > >> experiment, but a contender for entry-level scanning - but it's only > >> part of the hardware side. The DAVID project uses just laser and > >> distributed light methods (at current, IIRC), so not a compatible > >> software piece. There are retail packages that speak with a Kinect or > >> Xtion, my favorite low-cost at the moment is Manctl's "Skanect", but I > >> also like the free Faro (tickler), "Scenect". There are of course > >> others. Most are Win32 or Win64 offerings only. OpenCV is often used as > >> a framework for open-source attempts, so not all hope is lost if someone > >> wants to try.... > >> > >> In a commercial environment, I do create and provide "difference scans" > >> of parts in some cases as required by a client, but it's pretty rare. A > >> big thing to note about volumetric scanning versus probing is that > >> scanning gets you a profile, and it takes a lot of time; probing gets > >> you parametric data and can be extremely fast. > >> > >> To implement an in-process scanning technique effectively, I would have > >> to do it in between machining operations - not just at the end, as one > >> part feature may be dependent upon the next, such as a helical thread > >> inside a drilled then bored hole) - and although most faults like that > >> would cause tool damage, I wouldn't want to write part programs so that > >> each individual feature is a separate operation (that's what automation > >> is supposed to make easier!) - thus the logic decision as to how to > >> "fix" the problem won't exist. > >> > >> Even if it did, one would have to scan a "known-good-master" at each > >> step of the production for the test scan to reference against. If you > >> want accuracy, measuring scale on a single volumetric scan is near > >> impossible. You need to have many angles and views stitched together to > >> see past obstructions. Any imperfection in the part, including > >> unintended, is recorded [perfectly]. > >> > >> Furthermore, the scanner is unable to understand chips, swarf or coolant > >> sitting on the part - it will look like a fault in the part and raise an > >> alarm. Get coolant on the lens and your scanning is of no value. > >> > >> Probing, on the other hand, can be more easily automated, and directed > >> towards achieving the stated goal - whether or not a particular feature > >> is within tolerance. > >> > >> I use both laser and depth-based scanning plus probing for a variety of > >> tasks, but only probing on my machines. > >> > >> I would liken volumetric scanning versus probing to the earlier > >> implementation of a webcam (camview by pavel et al, for example, which I > >> really do applaud) for tool-length-setting (and more) versus a touch > >> probe. Although I'm enamored with having a non-contact tool setter, a > >> camera is much less tolerant of mistakes or changes in the environment > >> than a touch probe. When you just want to get parts out, the touch probe > >> "JustWorks". > >> > >> That's not to say that having a volumetric scanner as a tool in a > >> machine isn't a possibility or a value, but the historical intent for > >> LCNC not to require a "64bit 8-core watercooled machine with Cray > >> loadbalancing (sic)" makes it a difficult challenge to have it > >> integrated with LCNC. My preference would be to have it on a separate > >> machine as a standalone application, but load the sensor as a tool when > >> needed. The benefit is the automation of the motion of the camera > >> (instead of human hand) which in that aspect, would return a much more > >> accurate result. Since the software has to "chew" on the scanning > >> result, it would actually be dangerous to have this type of interruption > >> (and I guarantee it would be an interruption) to the safety of the LCNC > >> realtime loop. > >> > >> Ted. > >> > >> > >> > ------------------------------------------------------------------------------ > >> This SF.net email is sponsored by Windows: > >> > >> Build for Windows Store. > >> > >> http://p.sf.net/sfu/windows-dev2dev > >> _______________________________________________ > >> Emc-users mailing list > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > > > > > > > > -- > > We conclude that the Second Amendment protects an individual right to > keep > > and bear arms. That right existed prior to the formation of the new > > government under the Constitution and was premised on the private use of > > arms for activities such as hunting and self-defense, the latter being > > understood as resistance to either private lawlessness or the > depredations > > of a tyrannical government." - U.S. Court of Appeals, D.C. Circuit, March > > 9, 2007 > > > > > > > > jeremy youngs > > > > > > -- > We conclude that the Second Amendment protects an individual right to keep > and bear arms. That right existed prior to the formation of the new > government under the Constitution and was premised on the private use of > arms for activities such as hunting and self-defense, the latter being > understood as resistance to either private lawlessness or the depredations > of a tyrannical government." - U.S. Court of Appeals, D.C. Circuit, March > 9, 2007 > > > > jeremy youngs > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Windows: > > Build for Windows Store. > > http://p.sf.net/sfu/windows-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- dos centavos ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
