I've been thinking include OpticalFlow whit laser sensor point.
all came into my mind after seeing this post.

I've been thinking include OpticalFlow whit laser sensor point.
all came into my mind after seeing this post. or I I think it would very accurate. What do you think?.
but as this in the arducopter?3689459335?profile=original


http://ashishrd.blogspot.com/2006/11/obstacle-detector-using-webcam-and.html

Hi everyone! I’m back with another webcam project, as usual. :) I’ve been having a lot of fun making cool things using my webcam over the last couple of months. This time, I’ve created an obstacle detector which uses a cheap laser pointer and a webcam to determine how far an object is from the camera. I worked with my cousins, Anuj Karpatne and Prateek Raj on this project.

There are all sorts of range finding devices available in the market like ultrasonic and infrared range finders. All these devices work well, but where portability and cost are of primary concern, this technique could be more desirable.
3689459365?profile=original

So, here’s how it works. A laser pointer is fixed below the camera at a known distance (as you can see in the picture above). The pointer is kept parallel to the optical axis of the camera. Then, a laser-beam is projected on an obstacle which is supposedly in the camera’s field of vision. The scene, along with laser dot is captured by the camera. Then, the image is scanned for the brightest pixels (we are assuming that the laser dot is the brightest point in the scene). Then, we calculate how far along the y-axis the laser dot is from the center of the image. The farther from the center, the closer we are to the obstacle. So, the distance from the object (D) is inversely proportional to the number of pixels from the center of the image (y):

D = hY/2y * cot (A/2)
Where the constants used are:
h = the actual distance between the laser pointer and the optical axis of the camera.
Y = total number of pixels along the y-axis
A = angle of view of the camera

As these values are constants, we obtain,
D α 1/y
Or, D = k/y (where k is the proportionality constant for all the constants used above)

We used an experimental approach to determine the value of k. We wrote a simple program in C# to do the entire image processing work and for finding the position of the laser dot in the scene. We calibrated the apparatus by placing an obstacle at known distances from the center of the camera and noting down the number of pixels the laser dot is from the center of the image along the y-axis. After taking several readings, we obtained the value of k. By using this value, we were actually able to determine how far an obstacle is, from the camera.
Well, we had a lot of fun working on this project! I hope you find it interesting. I’d love to hear your comments and ideas. :)


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  • 3692433561?profile=original

    LinkSprite JPEG Cámara a Color de interfaz TTL

    http://mbed.org/cookbook/Camera_LS_Y201

    3692433446?profile=original

  • Ritchie;

    who do you think of this camera, might work?. when ttl and with good resolution.

    http://www.sparkfun.com/products/10061

  • had considered this 50mw Green Laser Pointer With 5 Blades 7km Effects. 3692433504?profile=original3692433516?profile=original

     since that is needed is a good work light for the camera and measurement. supporting evidence;I am doing with my camera controur laser hd 1080.3692433409?profile=original

  • Norman.  Just taking a shot at this.  If you have a 500mw green laser, would it work better for a longer distance?

  • 3D Scanner

    It uses avicap32.dll so should work with most webcams. No support, no warranty, no liability.

    2 years old but works

  • I think I will not go to concerts and clubs where laser use. not to be blinded.

     think the chances of this laser affects the human eye is almost inposible
    first, the vehicle is in motion I can not point to the eye for more than a second.
    second, would have to see the bottom-up publishing vehicle in a right angle by more than 20 seconds looking at the laser.
    third, this is for low level laser and use as a supplement to maintain altitude in conjunction with the Optical Flow Sensor.

    In practice shooting with my gun laser sight, 5 meters a millimeter of movement in a second I will not give in the center of the target, and we're talking about a center of diameters 4 centimeter  human eye has a 1 centimeter in diameter.
    I must be immobile for a period of 2 to 3 seconds with the laser pointing right in thecenter of the target.


  • The only reason this has not been done on our systems is because it does not have the processing power to use a camera with sufficient resolution to create viable detection. We need both good resolution (100pixels on one axis at least) and reliable framerate (10Hz). Optical flow sensors are great at being low overhead but the resolution isn't high enough.I know we have someone on here that creates those sensors so this could be a reality at some point but until we get a low overhead sensor USB is our only option which is no use.

    The reason I say about the resolution and framerate is I did this 2 years ago upgrading Colin Ords 3D scanner to .NET (which if you are interested I'll zip it and put up here - although it may be here already Ive spent long enough here :D). Basically whatever your biggest resolution is half it and that is the useful resolution for parallel distance measurement. Parallax measurement like the 3D scanner I created uses trigonometry to use the entire resolution.

    Massive problem is off axis light is skewed by the lens characteristics and the math for that is not kind.

    Sorry to put a downer on it but without a raspberry pi on board or some other tiny PC we are stuck with low overhead stuff. If you track the brightest part for an axis and add a wine glass stem in front of the laser thats a 3Dscanner.

  • Project download page

    for those who want to test the project

    http://www.codeproject.com/Articles/91470/Computer-Vision-Laser-Ran...

  • More details of this fabulous project

    http://www.robosapiens-india.com/engineering_projects_details.php?i...

  • Autonomous RC Car with Laser Based Obstacle Detector

    http://ashishrd.blogspot.com/2007/02/autonomous-rc-car-with-laser-b...

    http://vimeo.com/141198

    Hello Readers!

    This is my first project with the computer controlled RC car, I made. Instead of purchasing ultrasonic obstacle detectors, I used my laser based obstacle detector with the RC car to turn it into an autonomous vehicle. The computer determines the position of the laser dot in the webcam's field of view. Based on its position on the y-axis, it determines how close the obstacle is, in front of the car. When an obstacle gets really close, the computer stops the car and turns it until it finds a place with no obstacles in close range. Check out the video above to see it in action! I apologize for the camera shakes in the video. I was finding it really difficult to do several things at the same time. Anyway, I admit that it would be much more fun and exciting if I had a wireless webcam. I can't stop thinking of the possibilities!3692431302?profile=original3692431260?profile=original

    Autonomous RC Car with Laser Based Obstacle Detector
    Autonomous RC car with laser based obstacle detector on Vimeo Hello Readers! This is my first project with the computer controlled RC car ,...
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