I get that you are using a database to compare the object and recognize it but what is the name of the method that does so and on what basis does it do the comparison. It would be much better if you can clarify this in the course itself. Thanks.
Hi,
Have a look at the ofitial ROS documentation that it might give you some extra info: http://wiki.ros.org/find_object_2d
Its using SIFT, SURF, FAST, BRIEF and other feature detectors. Here is a paper where you have explanations on how it works: https://arxiv.org/pdf/1710.02726.pdf
Hope this guides you to the right place.
For sure this si not the only way to recognise objects. There are many other methods, one of them is using DeepLearning models. You have examples on how to use that in the Tensoflow and other AI related courses in TheConstruct.