I am trying to build a high-tech scarecrow using a opencv-bird-detector. Following the tutorial http://coding-robin.de/2013/07/22/train-your-own-opencv-haar-classifier.html I created 7000 positive samples (from 400 images) and 750 negatives. The resulting classifier detects mostly anything, from grass to blue skies. It even accepts the negative samples.
I wonder why this doesn't work at all. One thought I have is that maybe the positive images are too diverse, showing birds in trees, on the road, walking and flying. I used only 4 different kinds of birds (the ones I expect to eat my cherries). On the other hand that's what I understood the training is meant to handle.
I know I could use motion detection for a first approximation, but with winds etc. that doesn't seem sufficient.
Any idea?