Welcome to the world of OpenCV and object detection using cascade classifiers!
Some insights
- List item
- Start by completely ignoring the haartraining interface. We know there are TONS of tutorials using it out there, but it is outdated! Rather use the updated C++ interface called traincascade.
- Yes it focusses on a complete class of objects, but it all depends on how you define that class based on its training samples. If you supply only pictures of 1 cat species, then it will only detect and generalize well over new samples of that species. But if you succeed in supplying a lot of different cat species, then yes, it will be able to detect and generalize over them all looking for more general cat like properties.
- Keep in mind that a cascade classifier is NOT rotation invariant. So stick with samples to a single rotation, then rotate your image for detecting on multi rotations. It is multiscale however.
- Yes imageNet contains large databases of classes like cars!
