“detectSURFFeatures” function is just a feature extraction tool, it will help you to extract important information about the image in a robust way. I am assuming you want your input not to be multidimensional data whereas descriptor gives multidimensional data. One way to tackle this is to use “bag of features”. It discretizes the space of descriptor and gives you a single vector.
You can check out furthermore on “bag of features” in
On the other hand, Target (t) vector you can construct it depending on whether you want to classify or detect something in Image.
For example, “an Iris dataset” has 3 classes and you want to classify the image in one of the three class, so target vector should look something like [0,0,1] (a categorical data) where “1” represent the image belong to that class.
Hope it helps!