ORB Algorithm: What Is Intensity Centroid?

Question

So, I am reading a paper about ORB: An Efficient Alternative to SIFT or SURF and it happens to calculate the direction of corner from it center . According to Rosin the author of the paper;moments of a patch is given by

moment

and the centroid is of the patch from the center is calculated using:

centroid

The direction of the patch is computed from

enter image description here

My question is what are these value of p and q and why is it out there?

score 4 · Accepted Answer · answered Mar 02 '14 at 11:41

4

p and q - order of the moments, it is the analogue of the mechanical moments (i.e. of force or inertia). Image moments are very basic properties of image, invariant to rotation, could be used as simple descriptor.

Example,

Moment of inertia Ix= I2 = mass *x_coordinate^2.

Image moment Ix2 = intensity * *x_coordinate^2.

http://en.wikipedia.org/wiki/Moment_(physics)

http://en.wikipedia.org/wiki/Image_moment

answered Mar 02 '14 at 11:41

old-ufo

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What or who determines the values of p and q. – motiur Mar 02 '14 at 11:55
It depends on what you need. – old-ufo Mar 02 '14 at 15:54
And in example in your question, p and q = 0,1. – old-ufo Mar 02 '14 at 19:11

score 2 · Answer 2 · answered Oct 19 '19 at 02:29

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Because wo want to get the centroid of the image(a block/patch) by the intensity. m00:p = q = 0,sum the intensity matrix. m10:p =1,q = 0,sum of the x-direction. m01:p = 0,q = 1,sum of the y-direction. (m10/m00,m01/m00) is the centroid.

answered Oct 19 '19 at 02:29

LingJun

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Forgive my poor English. – LingJun Oct 19 '19 at 02:31

ORB Algorithm: What Is Intensity Centroid?

2 Answers2