Note: Many of the images are cropped by hand. I did this so I could show the images off to my friends and family (since it was their pictures I took).
Note: In order to add control points I added a point and click function to matlab, two of the above functions are related to that: mouse_pressed.m and track_positions.m
Q1)
The quality of the morph is highly related to the number of control points. The more points, as long as they are accurate, the better the registration. Interestingly enough I found that more points were needed than I might have expected, but still a reasonable amount. And it's also very important to focus on certain areas of the image. For instance I was doing the morph with faces. Originally I thought that a single point in each eye would be sufficient. I later found that it took at least 3 points to get the eyes to match up in a realistic way. I was also surprised at how important it was to match up girls hair, their hair required a fair bit more work than I expected.
A good example of bad control points is the following morph. This was a morph between my brother and me. A total of 38 control points were used to accurately describe the morph. Yet we notice artifacts along the ears. Even though we have more control points, our ears aren't adequately explained. We could add an arbitrary number more of control points, but unless we added one on the two edges of the ears, it wouldn't benefit us much.