Is the crio powerful enough?

[davidthefat]

Originally Posted by gblake

Before you invest too much in this project, assume a reasonable error in the angles you are able to measure after you try to get both cameras to lock onto a single small point on the object. Additionally assume the object is not perfectly "broadside" to your two cameras. Then compute the range of distance errors that will arise as a consequence of those angular errors.

If you are thinking of using an FRC bot for the base of your triangle, and you are trying get the distances to objects that are scattered around an FRC field, You might be disappointed by the probable size of the distance errors

Or you might be perfectly happy. Just don't overlook the extreme precision required for accurate distance measurements across a reasonably wide field of view.

Blake

I am perfectly fine with "that object is close" "that object is farther" type of thing, I am not making the next mars rover or anything I don't need to be that exact, may be off by a foot or 2 is fine

[gblake]

Originally Posted by davidthefat

... off by a foot or 2 is fine

How about a foot or 50? ... There are important non-linearities in the calculations that magnify small measurement errors dramatically.

[davidthefat]

Originally Posted by gblake

How about a foot or 50? ... There are important non-linearities in the calculations that magnify small measurement errors dramatically.

I have no idea what that means, but... Its like the IR Range finders, the voltage output is a curve, gradually evening out and becoming very inaccurate; is this an example of your explanation?

[PAR_WIG1350]

I love trig

team 1350 used binocular vision in 2006 somewhat successfully, I wasn't there to get the specifics, but it used 2 CMUcams and trig, and that was with the old IFI rc, assuming there is a target that can be easily picked up at a low resolution, and the servos controlling the cameras are accurate enough (the closer the object, the less acurate they need to be), it should be *relatively simple. Streamlining the rest of the code to free up memory should also help.

Hint, research "boids", it could help with programing how to react to other robots.

[JamesBrown]

Originally Posted by PAR_WIG1350

I love trig

team 1350 used binocular vision in 2006 somewhat successfully, I wasn't there to get the specifics, but it used 2 CMUcams and trig, and that was with the old IFI rc, assuming there is a target that can be easily picked up at a low resolution, and the servos controlling the cameras are accurate enough (the closer the object, the less acurate they need to be), it should be *relatively simple. Streamlining the rest of the code to free up memory should also help.

Hint, research "boids", it could help with programing how to react to other robots.

If memory serves, you guys also used a Gumstix as a Co-Processor to handle the stereo vision. I dont think the old controller could handle two CMU cams very well.

[Nadav Zingerman]

The cRIO is powerful enough so that a few trig functions make absolutely no difference. We used a couple dozen of them for our drive routine with no noticeable slow-down at all. Using them in the vision routine should be no different. The main thing that will be slow is image processing, which is mostly affected by the camera resolution.

In addition, I imagine that the existing trig functions are already highly optimized for real-time applications, as that's what the cRIO is for. The cRIO has a floating point processor, so that should work pretty well.

Also, in my experience, one camera is good enough for range finding, provided you know the physical dimensions of the target, which has been the case in the last few games.

[EricVanWyk]

This conversation is focusing way too much on the cost of the trig functions, compared to the cost of the vision functions. Trig is a lot more expensive than addition and subtraction, but trivial compared to vision.

[kamocat]

In summary:
Yes, the cRIO is powerful enough for trig functions.
No, the cRIO is not powerful enough for stereo image processing at 60hz, without reprogramming the FPGA.

[kamocat]

Originally Posted by davidthefat

I have no idea what that means, but... Its like the IR Range finders, the voltage output is a curve, gradually evening out and becoming very inaccurate; is this an example of your explanation?

It's an secant function where x is your angle and y is your distance.
You can see that after about 60 degrees it gets very inaccurate.
The IR sensor, on the other hand, is exponential decay, which makes a slightly friendlier curve. (Your error at 75% maximum distance is only +-25% of the total range of the IR sensor)