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Handheld laser triangulation measure

Goes the distance
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BorgCo engineers have designed an innovative measuring device.

Given the availability of cheap laser rangefinders, a handheld unit has been produced that allows measurement of a linear distance by non-contact methods.

The device resembles a handheld barcode scanner. A red laser beam is emitted from the slot, although this is merely for guidance; the actual measurement is carried out by a pulsed infrared laser.

The beam is projected onto the surface to be measured. By manipulating the trigger on the device, the width scanned can be widened or narrowed. When the centre of the trigger is pulled, the unit registers the positions of the two extremities of the line and then by simple 3D geometry calculates the linear distance between them, which is then displayed on an LCD panel.

Any "clutter" between the ends of the guide line is ignored; the unit is only interested in the two end points.

Useful for measuring things not easily reachable; the spacing between brackets on house guttering, the distance between fence posts without struggling to pass a tape over intervening herbage, or the span between two tree branches to allow Christmas lights to be deployed in the most efficient way without resorting to a ladder and trial-and error.

8th of 7, Dec 09 2019

"Who hung the monkey ?" https://en.wikipedi...nimal_trial#Monkeys
British justice at its finest. [8th of 7, Dec 10 2019]

[link]






       Hmm. I'm thinking that handheld wobble is going to be the main issue here. As I understand it, you first aim it and adjust it until the two spots are aimed at the two targets you want to measure. This alone will be tricky, because you'll be looking at one target whilst trying to keep the spot still on the other one. But then you've also got to pull the trigger whilst holding the same aim - clearly doable, but perhaps not easy if you're not a gunslinger.   

       This could work if the device were held in some sort of fixed stand.
MaxwellBuchanan, Dec 09 2019
  

       Or (and here's a thought), how about a digital camera that indcludes a rapidly-scanning IR laser rangefinder. That would enable you to take a photo of a scene, and assign each image pixel a distance (from the camera). Then just click on any two points on the image, and software will tell you the distance between them.
MaxwellBuchanan, Dec 09 2019
  

       [+] easily bakeable. Two cheap rangefinders on a digital protractor. Angular resolution might be a problem depending on the distance you're expecting to use this with.
mitxela, Dec 09 2019
  

       // handheld wobble is going to be the main issue here //   

       <Sigh> Like we said, take more water with it. Or in Sturton's case, a bit less ... well, let's not go there.   

       // two spots //   

       No, it's a line, with two (2) ends.   

       // not easy if you're not a gunslinger. //   

       We fail to comprehend the problem there.   

       //some sort of fixed stand //   

       There's a threaded bush in the bottom of the grip so you can mount it to a standard photographic tripod. Or you could lean on something, a concept with which you appear to be rather familiar.   

       // camera that indcludes a rapidly-scanning IR laser rangefinder //   

       Good, but complicated; however, useful for postmission image analysis.   

       // how accurate you want it to be //   

       You get what you pay for.   

       // optical range finders and “tape measure” analogues are available at most hardware stores. //   

       They're all 1-D devices; this works in 3-D.   

       // Two cheap rangefinders on a digital protractor. //   

       Yes, but ours has it all in the one convenient package.
8th of 7, Dec 09 2019
  

       // Leica Disto [link] - good enough? //   

       No, because after you've bought one, you're then lacking an arm and a leg, which makes it difficult to use.   

       We're talking about a consumer grade device for under USD $50.   

       The same goes for handheld lidar. Oddly, not seen one of those on offer at a Wal-Mart ...
8th of 7, Dec 09 2019
  

       It doesn't do anything like what's suggested. The Disto 1 is a 1-D linear measure. It measures the distance from its own position to another position within its range.   

       Our device measures the distance between two positions, both at a distance from the device, by triangulation and 3-D geometry. You can do the same thing with a linear measure and (as [mit] suggests) a digital protractor - but it's hardly point-and-shoot. You could probably write an app to do the geometry for you, tho.
8th of 7, Dec 09 2019
  

       //indirect measurement by Pythagoras method// To do that, it must have some kind of angular sensor, which is what I was going to suggest.
MaxwellBuchanan, Dec 09 2019
  

       The problem with the accelerometers in that device is drift between shots. No matter how careful you are with trying to maintain the position of the device between the two shots, the accuracy is awful (yes, we've used one) even on a tripod.   

       Our device is a "one click" system with no need for the error and drift prone accelerometers.
8th of 7, Dec 09 2019
  

       // //indirect measurement by Pythagoras method// To do that, it must have some kind of angular sensor, which is what I was going to suggest. //   

       No. You must be thinking of the cosine law. The Pythagorean theorem assumes a right triangle. I just pulled out my Bosch GLM 35 and used it in this mode, and it worked fine. It doesn't measure any angle. The only limitation is that you have to be on a line that passes perpendicularly through the line you wish to measure at one of its endpoints, so as to form a right triangle between its two endpoints and the measuring device.
notexactly, Dec 10 2019
  

       // you have to be on a line that passes perpendicularly through the line you wish to measure at one of its endpoints //   

       That's exactly the irritating limitation that our design is intended to overcome. You don't need a right angle anywhere; knowing a, b and theta for any triangle, c can be calculated irrespective of orientation.
8th of 7, Dec 10 2019
  

       Or, you could just continue to use a trained monkey, equipped with a tape measure! - (otherwise that's you out of another job 8th)
xenzag, Dec 10 2019
  

       Well, if you have plenty of time to do the training you could always hire a french carbon unit and train them up; they are plentiful, and cheaper than monkeys because monkeys learn faster, smell better, and are easy to housetrain.   

       It's hard to understand how the people of Hartleypool made such a sad mistake; it must have been an exceptionally ugly, stupid monkey. <link>
8th of 7, Dec 10 2019
  

       Yes, but we don't want it now, or in a month - we want it three days ago, so that the "No, they won't reach between those two branches" argument can be resolved without scrambling up ladders in the wind, rain and gathering datkness.
8th of 7, Dec 10 2019
  

       // many have ToF sensors on the front (for facial recognition) //   

       Not being a phone user at the moment, the only one I have specific knowledge of is the iPhone X, and I was under the impression that that one used coded light, like the first-generation Kinect (not to be confused with the second-generation Kinect, which uses time of flight).   

       Speaking of time-of-flight cameras, how do they do in full sunlight these days? How about in full sunlight on Mars?
notexactly, Dec 20 2019
  

       [Chairborne Hero] my Wacom computer has (some form of) 3D scanning built-in, but I haven't managed to get it to work yet :-(
neutrinos_shadow, Mar 18 2020
  

       TIL Wacom makes drawing tablets with built-in computers now.
notexactly, Mar 20 2020
  
      
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