You don't really need any particular framerate, but the faster it is, the more useful it is. This is a triangulation scheme; so the position of the laser dot as seen by the camera (which is offset by some baseline from the laser source) determines the distance to the reflecting object. Each frame generates just one distance ranging value (unless you've got multiple beam intersections, like through a glass window, or windowscreen, at edges, etc). You put the laser+camera on a spinning platform so you can sweep out 360 degrees. If your camera does 4k fps and your assembly rotates at 10 Hz (600 rpm), you can then acquire 400 points per rotation, which gives you slightly better than 1 degree angular resolution for your range map. Those are the parameters of the "Neato Robotics" XV-11 robotic vacuum cleaner which maps out the borders of the room it is in, in real time.poing wrote:I didn't read the whole paper, but why do you need 4000 fps?
I see. The camera they used must have had a different architecture to permit the higher frame rate. Thanks for looking into it, anyway!jamesh wrote:The sensor only bins to 2x2, as you would expect, but it might be possible to skip multiple lines/pixels on readout. Not sure though - looking at the datasheet there is nothing obvious. I'll keep looking.
EDIT: registers 0x3814 and 0x3815 are the ones, but there are upper limits to frame rate based on the speed of the sensors ADC's, and they top out fairly soon once you get above 120fps or so (depends on the sensor, not sure of exact figure for the 5647)
Well I did say it was slightly ridiculous . Also, since I made the original request there have been other developments in the LIDAR field, with simple systems like Lidar-Lite ( http://pulsedlight3d.com/ ) now around $100, so no worries there.6by9 wrote:Actually your request is subtly different from jbeale's original (I think). AIUI His request was for effectively 2952x2 so that he could get a rotating line array. That sort of mode won't be added as it just gets too onerous to support all the different potential requests and use cases.
I've been looking at a lot of possible platforms for small, lightweight, inexpensive camera/vision development, including somewhat expensive CV cameras from PointGrey. Nothing else I have seen comes close to RPi for small, lightweight, and access to uncompressed camera data fast and with low overhead. Awesome platform for computer vision. I kind of got sick of people who thought that the act of doing something on the RPi made it (and them) clever, but in the realm of computer vision I think it is a fantastic platform.jbeale wrote:Currently I'm getting a lot of use out of the existing RPi camera for normal photo/video applications. There are various other dev-board type cameras (ARM-based systems, even Arducam, etc.) but to my knowledge nothing is even close to as well supported, capable, or useful as the RPi camera.
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