What is currently considered the "best" algorithm for 2D point-matching?

Question

I have two lists containing x-y coordinates (of stars). I could also have magnitudes (brightnesses) attached to each star. Now each star has random position jiggles and there can be a few extra or missing points in each image. My question is, "What is the best 2D point matching algorithm for such a dataset?" I guess both for a simple linear (translation, rotation, scale) and non-linear (say, n-degree polynomials in the coordinates). In the lingo of the point matching field, I'm looking for the algorithms that would win in a shootout between 2D point matching programs with noise and spurious points. There may be a different "winners" depending if the labeling info is used (the magnitudes) and/or the transformation is restricted to being linear.

I am aware that there are many classes of 2D point matching algorithms and many algorithms in each class (literally probably hundreds in total) but I don't know which, if any, is the consider the "best" or the "most standard" by people in the field of computer vision. Sadly, many of the articles to papers I want to read don't have online versions and I can only read the abstract. Before I settle on a particular algorithm to implement it would be good to hear from a few experts to separate the wheat from the chaff.

I have a working matching program that uses triangles but it fails somewhat frequently (~5% of the time) such that the solution transformation has obvious distortions but for no obvious reason. This program was not written by me and is from a paper written almost 20 years ago. I want to write a new implementation that performs most robustly. I am assuming (hoping) that there have been some advances in this area that make this plausible.

Answer 1

I saw a program on tv a while ago about how researchers were taking pictures of whales and using the spots on them (which are unique for each whale) to id each whale. It used the angles between the spots. By using the angles it didn't matter if the image was rotated or scaled or translated. That sounds similar to what you're doing with your triangles.

Answer 2

I think the "best" (most technical) way would to be to take the Fourier Transform of the original image and of the new linearly modified image. By doing some simple filtering, it should be easy to figure out the orientation and scale of your image with respect to the old one. There is a description of the 2d Fourier Transform here.

Answer 3

There is no single "best" algorithm for this. There are lots of different techniques, and each work better than others on specific datasets and types of data.

One thing I'd recommend is to read this introduction to image registration from the tutorials of the Insight Toolkit. ITK supports MANY types of image registration (which is what it sounds like you are attempting), and is very robust in many cases. Most of their users are in the medical field, so you'll have to wade through a lot of medical jargon, but the algorithms and code work with any type of image (including 1,2,3, and n dimensional images, of different types,etc).

Answer 4

You can consider applying your algorithm first only on the N brightest stars, then include progressively the others to refine the result, reducing the search range at the same time.

Using RANSAC for robustness to extra points is also very common.

Answer 5

If you're interested in star matching, check out the Astrometry.net blind astrometry solver and the paper on it here. They use four point quads to solve star configurations in Flickr pictures of the night sky. Check out this interview.

Answer 6

I'm not sure it would work, but worth a try:

For each star do the circle time ray Fourier transform - centered around it - of all the other stars (note: this is not the standard Fourier transform, which is line times line). The phase space of circle times ray is integers times line, but since we only have finite accuracy, you just get a matrix; the dimensions of the matrix depend on accuracy. Now try to pair the matrices to one another (e.g. using L_2 norm)