Militarizing your backyard with Python, Arduino, and computer vision.

I imagine the team behind Kinect feels the same way when lightsaber-anything gets made.

As a person who used those bindings in a couple of projects (this includes tutoring the computer vision course at uni) I will use this opportunity to say thanks.

I don't say this enough to people like you, so THANK YOU SO MUCH!

Awesome, I have been using the your work a lot recently. I do have one question though, is SIFT available in the python bindings? I have not been able to find it.

Thanks for contributing your time, it has made my life much easier.

Hey, thank you for that code! Your OpenCV bindings made more than one appearance at PyCon this year. I used it in my "Angry Birds playing robot". Thank you, thank you, thank you! http://pyvideo.org/video/683/building-a-robot-that-can-play-...

Thanks! You definitely made things much easier for me. I had also played around doing some raw ctypes work with OpenCV and now greatly appreciate your efforts.

I think a fair number of nation-states would be willing to pay a lot of money for a version of this system they didn't have to program themselves. And had more firepower, of course.

I'm not sure. I've thought about building this kind of system from time to time, but I've never gotten around to it. I'd pay up to $75 for a simple version that keeps pigeons from my balcony. Nothing fancy required: it could fire at anything that moved. I would switch if off if I wanted to use the balcony myself. I wonder whether $75 would be enough to make this a viable product.

Adding complementary features such as edges (I'm guessing this is what you mean by lines) tends to improve the accuracy. It would also be possible to do this in real time.

I don't have time to watch the full video so I don't know what features he is currently using, but in object detection nowadays most people are using some variant of the SIFT descriptor. These are built not upon edges but on the image gradient per-pixel. The current 'hot' feature in terms of frequency of use is probably Histograms of Oriented Gradients (HOG) which do exactly what they say on the tin: Take a region of the image and count how many times a particular gradient direction occurs and the total magnitudes. Slightly more difficult to run in real-time but libraries exist.

I didn't show the false positive video. :P There were some additional features thrown in, but for presentational simplicity I went with some strong, easy ones to explain. I think one thing helped keep FPs low was some frame-based signal thresholding. So, I required a significant squirrel signal (over multiple frames) before it went hot. That prevented any small FP blip to trigger the gun.

I was there too :) It was such a fun talk, especially the part where in the end of the demo video, the squirrel stopped caring about the water cannon anymore, and decided to steal food while getting sprayed on. I wonder if there is a better way to deter them instead of bigger water cannons?

You'd have to keep the sprinkler system constantly pressurized, though. I've never seen one that can do that - they all take x seconds to really get going.

Well sure, but its not really about that, its about the process, figuring out how to do this stuff and then doing it is extremely enjoyable and really cool, as is doing a talk for others who think the same thing.

He has trees from which the squirrels can leap to the feeder

I can tell you right now that those don't work at all. We've got a few on our feeders with NOTHING else around them and the squirrels still get on them. They only work if you have a single feeder/pole within about 10 feet of each other. Those little fsckers pull some ninja-esque moves jumping from metal pole to metal pole to get around them. It's entertaining to watch but it can get expensive since when they get up there they eat their fill which can sometimes be 1/6th to 1/5th of the feeder at a time.

Innovation in technology comes from using technology in ways it wasn't intended, not necessarily what is the most efficient.

We have chickens too, around 25 free range + a pony + a few ducks, and had issues with dogs and wild coyotes. I think harming the animal is a bit inhumane but I totally understand where you are coming from. Remember you are a guest in their space.

Here are some suggestions that have worked for our farm:

1. Pee around the coop. Enough said.

2. Get a puppy and train him. We have an aussie that does a great job, but there are other breeds that make even better farm dogs.

3. Train the chickens to go back into the barn when the sun goes down. This isn't very hard and most of the time they will do it themselves.

4. Motion sensor and/or electric fence on a timer.

5. Be aware; this is by far the hardest thing.

Our first year we lost 10 chickens. If that's not motivation enough to do something, I don't know what is but I would never hurt another animal for doing what they do naturally.

I thought about going that direction, but was concerned the birds might eat the pellets.

Relevant XKCD: http://xkcd.com/382/

Squirrels are notoriously ingenious at raiding feeders. They are really good at defeating feeders that are specifically designed to be "anti-squirrel" too.