[question] ImageMatchingMultiSfM matching modes

[natowi]

Describe the problem

I could use some clarification for the Matching Mode:

ImageMatchingMultiSfM

Matching Mode description: The mode to combine image matching between the input SfMData A and B (notation is not optimal):

"a/a+a/b" for A with A + A with B. "a/ab" for A with A and B. "a/b" for A with B.'

This is how I understand the Input data is matched: 'a|a+a|b', -> merge (A with A) + (matches between A and B) -> Why (A with A) ? +? 'a|ab'-> merge A with (merge of A and B) ? 'a|b' -> merge (A with B)

It is difficult do understand, as this node computes matches between two inputs AND merges them.