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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

  1. Militarizing Your Backyard With Python:Computer Vision and the Squirrel Hordes Kurt Grandis PyCon 2012
  2. Overview● Background & Goals● OpenCV ○ Working with Python● Detecting Squirrels ○ SVMs ○ Squirrely features● Shooting Squirrels● Wet Squirrels● Next Steps
  3. The Great Backyard Bird Count
  4. Squirrels...
  5. Sentry Water Gun
  6. SystemSensor (Camera) Blob Detection Targeting Shoot the Squirrel Squirrel Detection
  7. OpenCVOpen Source Computer Vision● Image Processing● Video Analysis● Feature Detectors● Object DetectionC, C++, Python Interfaces
  8. Python & OpenCV● Support for native Python structures● Works with numpy● Efficient data sharing
  9. Sensor : Webcam
  10. 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)
  11. Blob DetectionHow do I find regions of interest (i.e. Blobs)?● Birds● Squirrels● Neighbor ChildrencvBlobsLib (OpenCV function)
  12. Background SubtractionForeground SegmentationNoisy BackgroundCodebook Approach
  13. Squirrel Detection
  14. Support Vector Machines (SVMs)Supervised Learning from svm import * ...Classification c = my_trained_model.predict(vector)Featureslibsvm
  15. Squirrely FeaturesWhat is squirrel-ness?● blob size● histogram analysis of blob● entropy of blob (texture)
  16. Blob Size
  17. Color Histogram
  18. 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] )
  19. SVM & Classifing Blobs● blob size● color histograms● entropy of blob (texture) Classify!
  20. Shoot the Squirrel
  21. The Gun
  22. The Turret
  23. Python and ArduinoArduino Unopyserial import serial arduino = serial.Serial(device, BAUD_RATE) arduino.write("a")Project Sentry Gun
  24. 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 really
  25. Next Steps● Better Optics● Stronger Firepower ○ Laminar water jet ○ Pressurized water pump● Python-On-A-Chip● Bird Classifier & Counter
  26. Questions? animals were harmed in the development ofthis project. Bird seed and other snacks wereprovided to all participants free of charge.