问题
The SIFT descriptor is a local descriptor that introduced by David Lowe. This descriptor can be splitted up into multiple parts:
1- Constructing a scale space
2- LoG Approximation
3- Finding keypoints
4- Get rid of bad key points
5- Assigning an orientation to the keypoints
6- Generate SIFT features
So, my question is:
What is the computational complexity of SIFT descriptor? something like O(2n+logn)
回答1:
Here's a paper that talks exactly about this.
The actual time complexity for a n by n image is apparently
where x is the neigborhood of the tile,pi,po are the number of input, output pins of the chip, α,β,γ are the feature fractions, and Γ0,Γ1,Γ2 are the input, compute, output clocks.
来源：https://stackoverflow.com/questions/32667635/computational-complexity-of-sift-descriptor