September 2012
I am trying to build a close-range 3D location system that works within about a 10 ft square area.
I need X, Y, and Z coordinates from one fixed point; then record the points into a computer.
I prefer a laser based system that records its rotation in degrees and for both Z and X axis and the length of the laser to the object for a calculated Y coordinate.
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Since you didn't mention precision, price and ease of construction must be more important to you. Therefore, I don't think that a laser-based system is necessary or appropriate.
For approximately a three foot cube working space, you could use a webcam parallel to one axis and another webcam perpendicular to that axis. Using an object of known size and location, you could calibrate that photogrammetry system in software.
If you feel you need a laser system, a lens in front of a Microsoft Kinect system could shrink it's working space, though that might not be necessary in your application. Both of these systems assume that there is an unobstructed view of the target (or targets), and that the object is reflective. Other approaches are necessary for transparent objects.
Can't help with most of your questions except for one "length of the laser to the object for a calculated Y coordinate" is a pretty tricky thing to do, even with a computer, at such short distances. The speed of light is about 300 million meters per second (roughly 1 billion feet/sec). If you are thinking of blinking the laser then measuring how long it takes the beam to bounce off an object ten feet away and return to a sensor then you'll need to measure time intervals of a fair bit less than 1 billionth of a second. 1 GHz is a billionth of a second.
To get an accuracy of say one foot out of ten you would need to measure time at 10GHz, to get 1" you would be up near 100GHz. That is possible but not for cheap. Even a $1000 O’scope wouldn't be able to measure a time interval that short. I believe vision systems like what you want (e.g., XBox Kinect) use multiple lasers and a video system. With two laser beams you get two dots, if the two beams are parallel the distance between the dots is proportional to the distance from the laser to the object. A PC does the distance calculation based on the video image.
I think your best bet would be to start with an XBox Kinect system and mount the transmitter/receiver on a rotating platform. The Kinect will do 3 dimensions all by itself. The rotating platform will let you look in all directions. I believe there are software platforms for communicating with a Kinect system.
