I'm working on Multiple Image Stitching and I came around the term Pairwise Matching. I almost searched on every site but am unable to get CLEAR description on what it exactly is and how it works.
I'm working in Visual Studio 2012 with opencv. I have modified stitching_detailed.cpp according to my requirement and am very successful in maintaining the quality with significantly less time, except pairwise matching. I'm using ORB to find feature points. BestOf2NearestMatcher is used in stitching_detailed.cpp for pairwise matching.
What I know about Pairwise Matching and BestOf2NearestMatcher:
(Correct me if I'm wrong somewhere)
1) Pairwise Matching works similarly like other matchers such as Brute Force Matcher, Flann Based Matcher, etc.
2) Pairwise Matching works with multiple images unlike the above matchers. You have to go one by one if you want to use them for multiple images.
3) In Pairwise Matching, the features of one image are matched with every other image in the data set.
4) BestOf2NearestMatcher finds two best matches for each feature and leaves the best one only if the ratio between descriptor distances is greater than the threshold match_conf.
What I want to know:
1) I want to know more details about pairwise matching, if I'm missing some on it.
2) I want to know HOW pairwise matching works, the actual flow of it in detail.
3) I want to know HOW BestOf2NearestMatcher works, the actual flow of it in detail.
4) Where can I find code for BestOf2NearestMatcher? OR Where can I get similar code to BestOf2NearestMatcher?
5) Is there any alternative I can use for pairwise matching (or BestOf2NearestMatcher) which takes less time than the current one?
Why I want to know and what I'd do with it:
1) As I stated in the introduction part, I want to reduce the time pairwise matching takes. If I'm able to understand what actually pairwise matching is and how it works, I can create my own according to my requirement or I can modify the existing one.
Here's where I posted a question in which I want to reduce time for the entire program: here. I'm not asking the same question again, I'm asking about specifics here. There I wanted to know how can I reduce time in pairwise matching as well as other code sections and here I want to know what pairwise matching is and how it works.
Any help is much appreciated!
EDIT: I found the code of pairwise matching in matchers.cpp. I created my own function in the main code to optimize the time. Works good.
