PyCon 2012: Militarizing Your Backyard: Computer Vision and the Squirrel Hordes

Militarizing Your Backyard With Python:Computer Vision and the Squirrel Hordes Kurt Grandis PyCon 2012

Overview● Background & Goals● OpenCV ○ Working with Python● Detecting Squirrels ○ SVMs ○ Squirrely features● Shooting Squirrels● Wet Squirrels● Next Steps

The Great Backyard Bird Counthttp://www.birdsource.org/gbbc/

Squirrels...

Sentry Water Gun http://wiki.teamfortress.com/wiki/Sentry_Gun

SystemSensor (Camera) Blob Detection Targeting Shoot the Squirrel Squirrel Detection

OpenCVOpen Source Computer Vision● Image Processing● Video Analysis● Feature Detectors● Object DetectionC, C++, Python Interfaceshttp://opencv.willowgarage.com/wiki/http://code.opencv.org

Python & OpenCV● Support for native Python structures● Works with numpy● Efficient data sharing

Sensor : Webcam

OpenCV import cv cv.NamedWindow("camera raw", 1) capture = cv.CreateCameraCapture(0) img = cv.QueryFrame(capture) cv.ShowImage("camera raw", img) # Convert to Gray Scale gray = cv.CreateImage(cv.GetSize(img), cv.IPL_DEPTH_8U, 1) cv.CvtColor(img, gray, cv.CV_BGR2GRAY) # Canny Edge Filter cv.Canny(gray, edges, 50, 200, 3)

Blob DetectionHow do I find regions of interest (i.e. Blobs)?● Birds● Squirrels● Neighbor ChildrencvBlobsLib http://opencv.willowgarage.com/wiki/cvBlobsLibcvFindContours (OpenCV function)

Background SubtractionForeground SegmentationNoisy BackgroundCodebook Approach

Squirrel Detection

Support Vector Machines (SVMs)Supervised Learning from svm import * ...Classification c = my_trained_model.predict(vector)Featureslibsvm http://www.csie.ntu.edu.tw/~cjlin/libsvm/

Squirrely FeaturesWhat is squirrel-ness?● blob size● histogram analysis of blob● entropy of blob (texture)

Blob Size

Color Histogram

Entropy Measure of randomness Calculate entropy for regions of the blob ● Overall Entropy ● Stdev Entropy ● Left Mean Entropy - Right Mean Entropy h_prob = [ h / histo_sum for h in histogram ] entropy = -sum( [p * math.log(p) for p in h_prob if p != 0] )

SVM & Classifing Blobs● blob size● color histograms● entropy of blob (texture) Classify!

Shoot the Squirrel

The Gun

The Turret

Python and ArduinoArduino Unopyserial import serial arduino = serial.Serial(device, BAUD_RATE) arduino.write("a")Project Sentry Gunhttps://sites.google.com/site/projectsentrygun/Python-On-A-Chiphttp://code.google.com/p/python-on-a-chip/

Results● Squirrels get wet● False positives extremely low● More satisfying if it camps the feeder● Need stronger firepower● Need larger water reservoir● Squirrels are extremely persistent...no really

Next Steps● Better Optics● Stronger Firepower ○ Laminar water jet ○ Pressurized water pump● Python-On-A-Chip● Bird Classifier & Counter

Questions?kgrandis@gmail.com@kgrandishttp://kurtgrandis.com/no animals were harmed in the development ofthis project. Bird seed and other snacks wereprovided to all participants free of charge.

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PyCon 2012: Militarizing Your Backyard: Computer Vision and the Squirrel Hordes

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PyCon 2012: Militarizing Your Backyard: Computer Vision and the Squirrel Hordes Presentation Transcript