Convert SURFpoints object MATLAB

Question

Is there any way I can convert the SURFpoints object, generated by matlab, into a matrix with x and y positions, for feeding into a neural network?

I am a pretty much complete beginner, but from what I can tell, and by looking at documentation, I wasn't sure if there was a way to get SURFpoints into neural networks?

Many thanks, Hugh

Answer 1

SURFPoints has a field, Location, that is an n x 2 matrix that has the (x,y) coordinates of each SURF point detected in the image.

Note, however, that SURF points have other attributes beside their location (such as scale and orientation). If you only take into account the (x,y) locations, you are throwing away a lot of data.

Also, it's unclear how you would feed this information into a neural network. A neural network, like many other machine learning models, expects a uniform length feature vector of an entity. If your task is something like image classification, you'll have to come up with some way to convert the list of SURF points into a feature vector that captures the properties you want your classifier to care about. Depending on your application, a neural network may or may not be the best way to go. In the context of computer vision and image processing, neural networks these days are more commonly used for unsupervised feature discovery (see "deep learning"). For supervised learning tasks, other models like boosted decision trees and SVMs give better theoretical guarantees and have fared much better in practice.