3D for Crazies

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    Default 3D for Crazies

    The recent posting which mentioned the toy nailbed, as used to give a 3D metal version of your face(ugh) got me thinking yet again about methods of extracting z axis information.

    There are various diy(almost) ideas with links already in the forum, and no doubt they will get posted here also.
    While waiting for some of them to come to fruition, I thought I might as well start a thread for other crazies like myself for whom ideas are easier to come by than cash.
    This is not to put off contributions by eminent engineers, etc, but just be warned that extra points are awarded for the intellectual distance between one idea and the next.

    Starting with the kid's toy, there seem to be two basic problems in getting something useful out of it.
    1. Low resolution, unless you can produce a version with piano wire, and 32dpi is ok for you.
    2. By extending the whole area upwards, little is gained except a metallic or reflective surface.
    This would at least give you a surface with a consistent property to be exploited by the scanning method.

    If the toy was reduced to a single line in the manner of the tool used for copying wood moulding sections, this then allows the raising of each contour above the level of the original.
    Sideways scanning of this would allow a fairly simple optical method of retrieving the shape of the silhouette against an illuminated background.

    A method like this has the possibility, given the resolution problem, of speeding up the production of z axis information, but still requires software to convert the file to a usable form.
    Some interpolation might be acceptable, of course, and if you run your machine in raster mode, the programme might be easy to write.(Beyond me, naturally, but I'm sure someone will tell me how.)

    My off the wall idea is to paint the object black, place it in a shallow dish, then just cover it with diluted milk, and photo it.
    This will give me in a single step a greyscale image of the whole area suitable for converting to a raster carving programme.

    Your turn.

    John

    Similar Threads:
    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    John,
    Really like your idea of the milk for acquiring images. Here in the US one can purchase ORGANIC diluted milk as the real thing. It's sold as 1%, 2%, or 5% fat content.

    My idea:
    I think that if someone could build a STEREO digital camera with electronics that could calculate the difference in the different pixels from the two images and would give an output for the X, Y, and Z coordinates, that we would be in business; That is, if we could afford the camera.

    Anyone care to take on the task?

    Jerry



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    Hi Jerry,
    How about moving the camera between shots, or does that introduce too many possibilities for inaccuracies to creep in ?

    Or split the view with an optical setup (binoculars plus mirrors/prisms)into a standard digital ?

    Organic milk - I drink nothing else unless it's got ethanol in it.

    I'll actually try the milk idea tomorrow. For now it's nightcap time.
    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    Default Digital 2 1/2D

    John,
    With a stereo camera, (it would have 2 sets of lenses and 2 different digital sensors) one would electronically have a true 2 1/2D view of the subject from one side only, not true 3D as stated in previous post.

    Just think of the old stereo photographs of WW1 or WW2 days that the military used for intelligence gathering, and the viewer that was used.

    Only a single photo would have all information needed to compute the topography for a 2 1/2D dimensioned part. The resolution could be near 1/1600th of an inch if the pixel layout was 1600 X 1600 which equates to 2.6 Megapixels. Many reasonably priced digital cameras attain 8 Megapixels now.

    The camera would not have to output any photos, just process the info into a data or pointcloud file usable to create 2 1/2 D g-code.

    I Have not given any thought yet to rotating an object and having overlapping photos taken. This action would require custom software which probably already exists in Military and NASA circles, but is probably not available to the general public.

    Here is a website relating to a camera setup: http://www.ledametrix.com/
    The crossed viewing is by crossing your eyes to see the true 3D images.

    Jerry

    Last edited by CJL5585; 12-05-2006 at 07:29 PM. Reason: Add Digital Stereo website.


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    http://www.camtronics-cnc.com/

    Before you all re-invent the wheel....take a look at this website.



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    Quote Originally Posted by ViperTX View Post
    http://www.camtronics-cnc.com/

    Before you all re-invent the wheel....take a look at this website.
    Oh, I don't want to re-invent the wheel, I just want to go from a wooden wheel to a radial low profile tire with custom rims.



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    "Like doing jigsaw puzzles in the dark"

    John,

    Could you elaborate on these puzzling things that you are "working on" in the dark?

    Jerry



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    Jerry, what are you doing up at 6 am or thereabouts ? Doing jigsaws in the dark ? No, I haven't tried it either, but it might be quite a challenge.

    Well I tried the milk photo, examples attached. First the object - part of an old drawer handle. Then the photo immersed in 1/50 milk in water. Then a screen shot of the greyscale imported into Designer, the Carvewright software.
    I didn't bother to spray it black, not that would have made a vast amount of difference. The crucial oversight, simple afterwords of course, is that the milk obscures detail as well as adding the desired to the greyscale.

    I'd earlier thought of using a dye solution, and converting the depth of colour to a greyscale, but the milk seemed easier.
    Anyway that's the next experiment, but will have to wait for a couple of days.

    Attached Thumbnails Attached Thumbnails 3D for Crazies-iron-jpg   3D for Crazies-iron-02milk-jpg   3D for Crazies-carved-iron-jpg  
    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    John,
    When you get something that works for you, I want to know the secret since I need the same setup.

    My son gave me a NEW FACTORY turnkey servo router system for christmas. He paid $3500.00 per the receipt. It is setup with 3 ea. Gecko 320's, 3 Pittmam servos with Pittman 500 cpi encoders, 8 TPI leadscrews, 2 120 volt switched AC sockets, and Everything just plugs togather, has limit switches, all cables etc. but some weird Supercam control software. I had it running under TCNC awhile ago, but it needs some setup and so forth.

    He also gave me a new un-opened dremel tool and a new un-opened wet/dry vac that he had received in Christmas's past.

    He is an outstanding human being. I taught him well, and it stuck. I am really blessed and also very thankful.

    Jerry



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    Quote Originally Posted by CJL5585 View Post
    John,
    When you get something that works for you, I want to know the secret since I need the same setup.
    ....... some weird Supercam control software. I had it running under TCNC awhile ago, but it needs some setup and so forth........

    Jerry
    Well well. That's the same software that I'm in the process(lengthy as ever) of setting up.
    I picked it up in the fall last year, so I suppose a year building isn't too bad by zone standards. The package was as per their kit - software, three steppers, a control box, cables etc., but no hardware as far as the machine goes.
    The guy I bought it from threw in the computer that the software was loaded on as well for free. Like you say, it's designed to just be plugged together.
    However the software is unusual compared with what most people use on the zone, with the g-code support seeming to be as limited as the designer thought necessary. Mine's the 98 version, and I see no season to lash out for the xp yet. Certainly a raster mode seems to be the way I'll start.

    Back to 3d.
    I'm next going to try immersing the same object, after I get some matt white paint today, into copper sulphate solution. This is the one simple innocuous solution that I can think of that doesn't dye the object(Even meths has a tendency to leave a purple stain).
    I've just thought of using malt vinegar, but that would probably attack the metal.

    It also occurred to me that if I put an object in a glass beaker of solution, resting on a turntable, I could then produce a complete 3D panorama of the surface. Having done the same with a plain cylinder as a reference, I could then remove the errors produced by the container.

    Now the tricky bit, where we get to the "jigsaws in the dark" - what do I do with the images. I've no idea how to get from there to a 3D mesh/g-code, or whatever is required.
    40 years ago I wanted to be a programmer, but never pursued it. There you go.
    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    OK, I will bite, what about triangulation, three laser beams (what else???) very small resolution, software to move the beams and recognize when all three are all aligned (I never said this was gonna be simple), calculate the beam's relative angles and use trig functions to calculate depth... simple

    Another method is to utilize a standard scanner, install a wing wong mounted to a doovalackey that will interpret the signals sent by the scanner head into a depth value. OK so the second idea isn't alltogether serious, but it is a concept nontheless.

    Failing that you could use latex rubber, immerse the part to be copied face down into a pool of the stuff, wait for it to dry and use it as a mold.

    OK... I got nothin'

    Russell.



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    Hi Russell.
    Your contribution is in keeping with my original intention of the thread.
    Please keep us up to speed on your development of the doovalackey.
    We had a wing wong, but it died.

    I, too, wondered about using a scanner, but mine doesn't like working upsidedown, so I thought about converting the milk into a jelly, then I could turn it out onto the scanner glass. Not sure about the effect of lowering the lid, though.
    Regards
    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    I'm not sure if I'm understanding what you are trying to achieve, but it sounds fun.
    Is this kind of thing any use?
    http://www.brucerayne.com/scanz_explain.html

    Regards Terry.



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    Quote Originally Posted by MrBean View Post
    I'm not sure if I'm understanding what you are trying to achieve, but it sounds fun.
    Is this kind of thing any use?
    http://www.brucerayne.com/scanz_explain.html

    Regards Terry.
    Ha !!! I knew that lasers would be the answer, is there anything you cant do with a laser ?

    Actually, this may not be that hard to do, well maybe not easy, but "possible".

    OK, its added to the "to do" list, right up there with router # 5...

    Russell.



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    Quote Originally Posted by greybeard View Post
    Please keep us up to speed on your development of the doovalackey.
    We had a wing wong, but it died.
    You probably had a European wing wong, notoriously hard to keep alive, I was going for a Asia/Pacific breed, very hardy but nearly impossible to catch.

    Quote Originally Posted by greybeard View Post
    I, too, wondered about using a scanner, but mine doesn't like working upsidedown, so I thought about converting the milk into a jelly, then I could turn it out onto the scanner glass. Not sure about the effect of lowering the lid, though.
    Regards
    John
    My biggest fear of that approach would have to be how to explain to my better half exactly WHAT I was doing if I got caught with jellied milk and the scanner.

    In all seriousness, if you had a laser line, and took photo's with a camera, possibly from 2 or three or more angles, averaged them, recomposed the result, applied a smoothing mesh, the result might be usable. I'm thinking of a rotating axis with the piece to be "cloned" in the centre, fixed laser line to one side, and another rotating axis inline with the first with the camera mounted facing to the middle, with set or programmable number of angles/photo's per index position of the job. What would be handy is the parts needed to do this :

    1 - Digital Camera : Show me someone who doesn't have one.

    2 - CNC knowledge and/or keen interest : You are on CNCZone, you're hooked

    3 - Stepper's : Lets see, no load, slow speed required, damn, floppy drive steppers would work.

    4 - Laser line : You can buy them here for less than $60.00 and they come with a free circular saw.

    5 - CNC router : OK so probably not needed, but I just happened to finish making one, and thinking of what project to build next...

    6 - Software : This might be the sticking point, but surely there will be a "Guru" reading this that could help.

    Might give this a bit more thought, but in the spirit of forward planning, I would think the machine needs to be large enough (in keeping with photocopiers and fax machines worldwide) to scan someone's butt... just a thought.

    Russell.



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    I wait to see the first milk jelly butt.

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    Till then, here's my latest trial. Same piece but sprayed matt white(not very successfully - the top lines broke through the paint and are still dark), then immersed in mouthwash !
    Flash photo, imported into Corel Photopaint, the contrast increased and converted to 8 bit greyscale. Exported to Designer as before.

    I can see the possibilities now, and think the nextstep is to try a much higher concentration of colour than the mouthwash had. I'll probably try a spirit dye for the next test.

    Attached Thumbnails Attached Thumbnails 3D for Crazies-carved-iron2-jpg  
    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    [QUOTE=epineh;226773] I'm thinking of a rotating axis with the piece to be "cloned" in the centre, fixed laser line to one side, and another rotating axis inline with the first with the camera mounted facing to the middle, with set or programmable number of angles/photo's per index position of the job. What would be handy is the parts needed to do this :

    Russell,
    I'm losing the plot here. (They all say I did years ago)
    Fixed laser line - vertical ?
    The second laser is giving me orientation and rotational axis problems.
    Is the piece rotating ?
    John

    It's like doing jigsaw puzzles in the dark.
    Enjoy today's problems, for tomorrow's may be worse.


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    epineh-

    That is exactly the idea I've been persuing over the last few weeks! I'm going to have some time this spring, and thought a nice DIY might be the design/development of a good 3D laser scanner... My concern has been in how accurate I could make the thing, after all we all want to be able to throw a hair in it and get a precise 3D model out, right?!?!

    In all seriousness, I think using the multiple camera shot per orientation of the article and laser might help iron out errors... The machine itself wouldn't be too complicated, and the software to drive it not much worse (just steppers and tell the camera to take a picture, then analyze pixels for color of laser) but I haven't looked to far on the math behind the smoothing algorithms... Come to think of it, I'll start a thread on that subject... Be a nice partner with this one about probes, they'll go hand in hand!



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    John, yup the piece is in the middle of the rotating table, vertical laser line, with the camera set at say (just picked a number here) 30deg rotationally to the laser line. The camera will see a profile, compare that to a "calibration" shot with a laser line dead centre (might have to play around with a flat piece of cardboard or MDF or similiar), and you should be able to calculate a depth relative to centre.

    As jabuffi mentioned, using varying camera angles will help to "sniff out" any dark spots caused by complex shapes, or simply to average out the profile for better accuracy.

    Once the photo (or series) is taken of one profile, the piece is rotated by whatever resolution you think will be adequate, then so on...

    If the depth from centre is worked out in software, you could use something like an Excel spreadsheet to do the averaging of the different camera angle values, then export this straight into g-code of sorts.

    I guess the trickiest part will be converting the image data to a set of depth values, and I'm sure that could be done with little fuss. Just had a thought, you could include a "middle pointer" - a cone shape pointing down (centred) just above the piece being scanned, the laser line will show as an angled line above the piece, this could be used as a centre reference for the profiling software... I think you have stopped me from making my second router here John... ah well, I don't have enough room for what I had in mind yet any way

    This will make an interesting Christmas project.

    Russell.



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