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Old 03-10-2016, 01:55 AM   #21
AntDX316
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Get some sort of waypoint GPS?
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It's my responsibility to make sure it works and know what could go wrong despite what everyone else is saying because they do not see what I foresee.
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Old 03-10-2016, 07:44 AM   #22
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Quote:
Originally Posted by AntDX316 View Post
Get some sort of waypoint GPS?
Could you expand what you mean by this, I have no idea
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Old 03-10-2016, 07:58 AM   #23
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Good job!

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Originally Posted by LinusLarsson View Post
Update, I started all over!

I digged more into the camera API of the rasperry and I am now outputing uncompressed YUV data from the camera instead of a H264 video stream. What this means is I get the data truly frame by frame (and get a timestamp on the frame as soon as get it).

This is a lot of data, every frame is 230kb so I can't of course save this to disk reliably. so what I do is to send the frames into a jpeg encoder on the fly and save the jpegs. The raspberry can't do this on one core, but it has four so I went multithreading for the encoding and saving of the images. Now I save the images over NFS (network) to a RAM drive on a Linux computer. It's extremely fast.

So my first program is scrapped, and a new one is in! It's a way better program, less steps to go through.

And now to the important part, accuracy!

I am seing jitter times from the camera of as max 9ms. What this mean is that I know a jpeg is captured somewhere within 9ms. This is extremely good and better than I had hoped for.

Doing the math on this taking some other variables into account I think I can have an accuracy of 1% if you run 250kmh over a 100M stretch. 0.5% over 200M. This is in my opininion nothing short of spectacular for this kind of cheap hardware...

What I like about this new program is it feeds you directly a bunch of jpegs with timestamps on. There is very little "programmer black magic" going on here, which means it's easy to explain exactly what the program do.
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Old 03-10-2016, 08:40 AM   #24
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Linus, what is the size of the window through which the heli/plank needs to pass iot be captured reliably?
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Old 03-10-2016, 08:59 AM   #25
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I have pointed the camera out of the window onto a tree to get a feel of the distance, and there where no problem recognising the birdhouse in the tree. The birdhouse is way smaller than a helicopter. This is about 20 meters away. So I think you could go quite far from the camera and still get a good picture. There would be no problem capturing the heli at speed at 20M and I think double that is also ok and still work out which frame is the one where the heli passes.

Fortunately for me when running at 90 fps the PI compromises the Y resolution of the camera to save internal bandwith. The X resolution is still good. I will be running at 160x480 to start of which internally in the camera is 160x160. I want to have a good Y FOV (480) but don't really care about the resolution, you should be able to pass the camera at great variances of height. The X resolution needs to be good but does not need or want as much FOV (160), it only needs to capture the helicopter as it flys by in a couple of the frames. Theoretically you could do 320 pixels in X resolution (the hardware can do it), but it would need a lens to be of any use. And that's too hi tech for now.

I think it should work out. There are tweaks that can be done if it doesn't, but this is where I have planned to start testing. This will probably be some time into the future though.
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Old 03-10-2016, 09:16 AM   #26
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Hopefully the winter will end soon, so I can take my preview hardware out and field test it. It's still all theoretical...
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Old 03-10-2016, 09:36 AM   #27
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Might not be bad if you have a highway nearby just for a feasibility test to see how it captures somewhat high-speed moving objects along with visible field of view.
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Old 03-10-2016, 11:16 AM   #28
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I actually have the field only kilometers away, and the snow is dissapearing at the moment. But I don't want to bring all the things with me I need for this in the cold. But it will soon be spring. And there is a lot I can work on in the meantime. Would of curse be better if I had a definitive answer on some things...
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Old 03-11-2016, 12:30 AM   #29
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Quote:
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Fortunately for me when running at 90 fps the PI compromises the Y resolution of the camera to save internal bandwith. The X resolution is still good. I will be running at 160x480 to start of which internally in the camera is 160x160. I want to have a good Y FOV (480) but don't really care about the resolution, you should be able to pass the camera at great variances of height. The X resolution needs to be good but does not need or want as much FOV (160), it only needs to capture the helicopter as it flys by in a couple of the frames. Theoretically you could do 320 pixels in X resolution (the hardware can do it), but it would need a lens to be of any use. And that's too hi tech for now.
This was an error of me. I missread a memorydump . The internal sensor of the camera is using 80 * 240 when outputing 160*480 image. I have an image here taken from my program, really bad but show a lot of what can be expected and interesting features. I do think it will suffice, small details can be seen such as the lamppost. The base of the tree is about half a meter across. And it's easy to make out lot of details even with the low resolution. The tree is still 20M away from the camera.

I go black and white, the camera is outputing YUV and the Y portion of YUV is the black and white image and is straight memory in the computer, no postprocessing needed. That is fast, and color is not needed.

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Old 03-11-2016, 02:30 AM   #30
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That looks good. Will a grey overcast day not hide the subject a bit? Sorry for my dumb questions as I know zip about these things.....
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Old 03-11-2016, 03:08 AM   #31
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I am not a camera guy. But I think you can see the helicopter whatever the weather. We are not trying to shoot world class pictures here...

I have something very exciting to show you guys.. This is straight output from my program, then screen casted a small slow motion movie player I built. Look at those small birds passing by (imagine a straight camera and a red line in the middle of the picture). Now the birds aren't as fast, but they are small. Video quality is even better on the original.

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Old 03-11-2016, 08:32 AM   #32
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Hopefully I can get out tommorow, temperature above freezing! Do some real field testing, and get a "make or break" for this project. I am optimistic.
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Old 03-12-2016, 09:55 AM   #33
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And here we have it, actual testing. I have to admit anything is harder the soon you get a camera in front of the helicopter, even flying straight. There are however some nice passes in here in the 150kmh range (Logo 690SX, GPS meassuring). I wasn't really trying taking it to the limit, The Logo can do like 170. There is no problem seeing what is going on even when flying far from the camera. None of the passes are uncomfortably close. And the faster you go, the easier it will be to see when you "pass the imaginary line". At the end of the video there are a brief moment where I show the shutter speed.

Please don't forget, I take this through extra encoding steps, and youtube. Raw material is better.

It was no sun out a little foggy. Just as the weather you where talking about Vinger. I call this initial testing a success.

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Old 03-12-2016, 03:00 PM   #34
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That looks really promising Linus, great work.
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Old 03-13-2016, 04:21 AM   #35
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Very nice. With some image processing using opencv you could probably get this to fully automated.
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Old 03-13-2016, 05:01 AM   #36
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Quote:
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Very nice. With some image processing using opencv you could probably get this to fully automated.
You mean like this
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Old 03-13-2016, 09:59 AM   #37
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This speed measurement is just a friendly frontend.

I'm actually building a turret system to take out invading plankers...
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Old 03-13-2016, 10:31 AM   #38
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Hehe
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Old 03-14-2016, 04:18 PM   #39
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Here is a preliminary GUI. It uses motion tracking to find the helicopter, then you step to the right frame. These images are from the same video (And the speed is bogus), I have not done two cameras yet.

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Old 03-17-2016, 12:05 AM   #40
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I have done som more hacking on the speed measurement project. First, I've upgraded hardware to PI3 and got the jitter times on the images down to 6ms, I really want to get this to zero or very close to in the future but I would need to hack the libraries for the PI, and that can wait.

I have also changed the way the images are transferred to the base station, it now uses HTTP instead of a mounted disk. That's just better and multiplatform, ie Windows ready, I normaly use Linux when programming these kind of things. I'm working to get a full HTTP API for starting stopping etc. going.

The PI3 is some serious hardware. It compresses 90 320*480 JPEGs a second on half a core. There are four cores.

So, it's shaping up. Becoming better. Still a lot to do though. But I see the end of the tunnel where I can at least try out the system for real. Need to get 2*60M network cable though. WIFI could work, but ethernet is one less problem to care about (it definitely works).
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