Page 1 of 9 12345 ... LastLast
Results 1 to 10 of 81

Thread: "Free" "LIDAR"

  1. #1
    Join Date
    Apr 2008
    Location
    Sacramento, CA, USA Area
    Posts
    5,341
    Rep Power
    173

    "Free" "LIDAR"

    Since LinuxGuy and I first started talking about the lasers that were being carried in the catalog here, I've been working on designing an effective but super cheap LIDAR. I've put a ton of time and thought into it, and I'm finally getting close to something to show for the effort.

    The basic theory is that we calibrate a camera to correct any abberation. Then subtract the image from the image (basically creating a flat image), and then scan a laser line down the area that the camera views. The laser needs to be above (works better than below) the camera by a pretty good bit, but as it scans down the object(s), the line will appear offset by a number of pixels depending upon how close it is to the focal plane of the camera. We're looking at the parallax of the camera and light source.

    Using trig, we can then figure out the distance of any given point in that three dimensional scene of objects. This is a point-cloud. We can assemble that point-cloud into a three dimensional image - but only as much of the image as our laser and camera can see.

    My latest experiments [finally] show some good progress, but with still some substantial limitations.

    - I need to use a better camera. I've been cheaping-out on this project from the start. Free/repaired lipstick camera at only 180 lines. It has horrible light sensitivity and is terribly noisey.

    - I need a more focused laser. I'm using a $0.50 pointer shining through a glass bubble-level capsule. The thinner the line, the more resolution and faster the scan can be run.

    - There's still a lot of limitations to my software. It takes a full second to scan 60deg, but only a couple milliseconds to process it. Part of that is the laser as above.

    - The resolution is pretty good, sub-millimeter (as you'll see), but really only accurate with this camera out six feet or so before it loses too much depth of field.

    - Another software limitation: I have to stop moving to scan. Since I subtract my images before running a 1sec scan, I can't keep moving or the subtracted image and the natural image will no longer match.

    - Calibration takes a good ten minutes, but is pretty stable over the entire session.

    Here's an image of my progress.

    What we see here is the depth-map that is created, this is from the camera's viewpoint, as you can see. I assembled the point-cloud in MatLab so that we could visualize what the depth looks like. As you can see, I've rotated it some counter-clockwise to show the depth-field.

    So the upshot is: I'm now confident that this CAN be made to work for next to nothing. There's still at least another month or two of coding on it, but this will at some point fly... It may not be as fast as a commercial SICK/LIDAR system, but it's going to work darn it!
    I Void Warranties�

  2. #2
    Join Date
    Apr 2008
    Location
    Nelson, New Zealand
    Posts
    1,356
    Images
    58
    Rep Power
    70

    Re: "Free" "LIDAR"

    M'mmm Interesting work Adrenalynn, I wish I had your talents in this area, Mine is modeling and mechanical, yours is programing, Oh, to have both.
    People yearn after this robotic dream, but you can't strip your life of all meaning, emotion and feeling and expect to function.


  3. #3

    Re: "Free" "LIDAR"

    Quote Originally Posted by 4mem8 View Post
    M'mmm Interesting work Adrenalynn, I wish I had your talents in this area, Mine is modeling and mechanical, yours is programing, Oh, to have both.
    Actually, Adrenalyn does have both of these skills. I've never seen any of her code, so I don't know what her programming ability is, but it's clear she has great mechanical and electronics skills. If she were developing things Open Source, she'd be a great contributor in both hardware and software.

    I'd rather skip the mechanical and PCB design stuff and go right to the software. I also do 3D modeling of my designs, and would like to learn more about doing simulations and CAM. My 3D CAD software has modules for simulation and CAM.

    8-Dale
    I can handle complexity. It's the simple things that confound me.
    Do everything in moderation, ESPECIALLY, moderation..
    Sometimes the only way to win, is not to play.. -- Stephen Falken

  4. #4
    Join Date
    Apr 2008
    Location
    Sacramento, CA, USA Area
    Posts
    5,341
    Rep Power
    173

    Re: "Free" "LIDAR"

    Although I've conservatively written more than 6,000,000 lines of code in my life, and if you're running Windows post-1996 you're likely running my code and architecture, I don't really identify as a programmer. Although I do modeling, electronics design, mechanical systems design, board layout, ... I don't really identify in there either.

    On the technical side, my specialty is a lot narrower. If someone needs my area of expertise, they _really_ need it. I'm a mathematician specializing as a numerical receipist. In other words, I solve problems by beating them to death with math.

    Robotics are an interesting avenue because I can play with my first love AND my second - problem solving in general - and that's where my broadest strength lies - solving problems in general.

    Job-title-wise, that makes me a CTO (Chief Technology Officer) or a minimum position of Lead Architect/Principal Architect.

    I write code to solve problems. I do mechanical design to solve problems. I do electrical engineering to solve problems. You get the idea...

    My doctorate is actually in business administration, where I... solve problems. Primarily operations issues, although I'm pretty solid in the finance/GAP side too.

    I really don't have the patience or attention span to sit down and bash out code every day. Nor do I have the patience to make things look really really pretty, like your Wall-E. I can turn out some pretty cool code in short sprints, like this laser ranger, but traditionally this is about the time I'm turning it over to a team - all the problems have been solved, now it's code-monkey work...

    I admire the tenacity and attention to detail that goes into something like Wall-E, but try as I might I know that I don't have that gift.
    Last edited by Adrenalynn; 07-20-2008 at 11:36 AM.
    I Void Warranties�

  5. #5
    robot maker Guest

    Re: "Free" "LIDAR"

    i know about that type of design
    thats really great you started on that,i havent had the time to try with my lasers
    have about 7 lasers and 2 line lasers,i even got a chance to get a optical bench
    but with all my robot projects,plus home projects and being a cook at my house ,kinda hard
    but good news going to retire over 20 years early
    and spend full time building robots,mostly i build and design high end in house test equipment for big companywhere i am in charge of the test and calibration lab ,been there 19 years ,i guess now you know my age ,also have electronic photography memory,if i see a design for a few minutes i can latter rembember the circuit and draw it
    and when i started building robots,started to learn programming ,besides robots and cooking ,i travel alot mostly once month or 2
    Quote Originally Posted by Adrenalynn View Post
    Although I've conservatively written more than 6,000,000 lines of code in my life, and if you're running Windows post-1996 you're likely running my code and architecture, I don't really identify as a programmer. Although I do modeling, electronics design, mechanical systems design, board layout, ... I don't really identify in there either.

    On the technical side, my specialty is a lot narrower. If someone needs my area of expertise, they _really_ need it. I'm a mathematician specializing as a numerical receipist. In other words, I solve problems by beating them to death with math.

    Robotics are an interesting avenue because I can play with my first love AND my second - problem solving in general - and that's where my broadest strength lies - solving problems in general.

    Job-title-wise, that makes me a CTO (Chief Technology Officer) or a minimum position of Lead Architect/Principal Architect.

    I write code to solve problems. I do mechanical design to solve problems. I do electrical engineering to solve problems. You get the idea...

    My doctorate is actually in business administration, where I... solve problems. Primarily operations issues, although I'm pretty solid in the finance/GAP side too.

    I really don't have the patience or attention span to sit down and bash out code every day. Nor do I have the patience to make things look really really pretty, like your Wall-E. I can turn out some pretty cool code in short sprints, like this laser ranger, but traditionally this is about the time I'm turning it over to a team - all the problems have been solved, now it's code-monkey work...

    I admire the tenacity and attention to detail that goes into something like Wall-E, but try as I might I know that I don't have that gift.

  6. #6
    Join Date
    Jul 2008
    Location
    Madison Wisconsin USA
    Posts
    50
    Images
    8
    Rep Power
    35

    Re: "Free" "LIDAR"

    Are you guys aware of the David laser scanner software? It has been under development for a while, was freeware but they may be charging now, but it used a line laser just as you describe Adrenalynn (I use a Home Depot laser level), and a webcam. The software builds up a 3d mesh model of what you are scanning. So far the applications are fairly small scale, and you need to do a calibration with a right-angled pattern so it knows how to calculate the mesh. But it works pretty slick, and they recently added some features. Check it out at http://www.david-laserscanner.com/
    (disclaimer- I'm in no way associated with the David project)

    @Linuxguy, what 3d software do you use? I'm heavily into Cinema4D and can use Maya, trying to learn SolidWorks too. C4d is not really intended for CAD tho, more for Pixar type character animation, but I may use it to simulate my mech!

  7. #7
    Join Date
    Apr 2008
    Location
    Sacramento, CA, USA Area
    Posts
    5,341
    Rep Power
    173

    Re: "Free" "LIDAR"

    Back to laser ranging -

    I'm beginning to think this is the wrong direction. I'm getting crazy insanely good resolution, certainly it wouldn't miss a chair leg, but except in an instance of object identification - I suspect this isn't the way to go about navigation. Do I really need sub-millimeter with all the overhead that involves? If I were trying to shoot down projectiles in mid-flight maybe...

    I'm thinking about going back to my original point-design that I tossed together when LinuxGuy and I were chatting about it in another thread, and just modify that for line detection. At first blush, I suspect all I really need is to fix the camera and laser a known distance apart, and then mount that assembly to a tilt head. Just build a map of the distances to everything in view, even +- 0.5cm is fine...

    I went back and completely rewrote my calibration algorithm - calibration is down from 10mins to <1min now. Using the same camera with better lighting as well, but it becomes apparent that focus is going to be the killer. That line needs to be razor thin over the entire visible area.

    Naw, I'm really starting to think that building a hires 3D map is for chumps. I was looking at the TTF (Time To Flight) systems like the SICK, and they are really very low resolution devices...
    I Void Warranties�

  8. #8
    Join Date
    Apr 2008
    Location
    Sacramento, CA, USA Area
    Posts
    5,341
    Rep Power
    173

    Re: "Free" "LIDAR"

    Quote Originally Posted by milw View Post
    Are you guys aware of the David laser scanner software? It has been under development for a while, was freeware but they may be charging now, but it used a line laser just as you describe Adrenalynn (I use a Home Depot laser level), and a webcam. The software builds
    Thanks for the pointer, I just checked 'em out. Surprised I missed 'em first search a couple months ago.

    Alas, totally inappropriate for robotics. It requires a known 90 degree plane be in place to wrap the line around. Great idea for 3D scanning objects, but that methodology won't work in the wild, in much the same way that the interesting 3D scanner in Make Magazine this last time won't work (requires the target to be rotated around a plane)
    I Void Warranties�

  9. #9
    robot maker Guest

    Re: "Free" "LIDAR"

    it seems that most everyone has some or more talents of each skills and 1 skills or 2 of what they do really good
    mostly we need to put each of our resources together and build a really good design
    i spend a very long time testing each part ,electronics or mechanical before i build the next part
    also dont like the full johnny five kit,i like to buy each part seperate as needed,some parts might need to be milled or special made,same for any robot project
    but i do like Adrenalynn work on the laser,thats the main design looking for mine,even servo magazine has info on using lasers with webcams,also from laser tracking designs on the internet i saved many links for diferent types to try ,one project getting near done is a sonar ring, ordered 25 sonars for a 16 sonar ring design,mostly the code will be the problem
    Quote Originally Posted by 4mem8 View Post
    M'mmm Interesting work Adrenalynn, I wish I had your talents in this area, Mine is modeling and mechanical, yours is programing, Oh, to have both.

  10. #10
    Join Date
    Jul 2008
    Location
    Madison Wisconsin USA
    Posts
    50
    Images
    8
    Rep Power
    35

    Re: "Free" "LIDAR"

    actually not just as you described, David has you adjusting brightness and contrast to get only the laserlight visible. Issues I've had are with objects that are not evenly colored- you get better reflectance/visibility off of white, very little to none off of transparent tinted plastic (I tried to scan the head of my white/black Robosapien V2).

Thread Information

Users Browsing this Thread

There are currently 2 users browsing this thread. (0 members and 2 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •