When I said soon, I meant in a day or two. Training a Haar cascade takes a lot of processing time. Training an LBP cascade is relatively quick. However, in either case, we need to download some big collections of images before we even start. Settle down with a reliable internet connection, a power outlet, at least 4 GB of free disk space, and the fastest CPU and biggest RAM you can find. Do not attempt this segment of the project on a Raspberry Pi. Keep the computer away from external heat sources or things that might block its fans. My processing time for Haar cascade training was 24 hours (or more for the whisker-friendly version that is sensitive to diagonal patterns), with 100% usage on four cores, on a MacBook Pro with a 2.6 GHz Intel Core i7 CPU and 16 GB RAM.
We use the following sets of images, which are freely available for research purposes...