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realcrane / BASAR-Black-box-Attack-on-Skeletal-Action-Recognition

BASAR:Black-box Attack on Skeletal Action Recognition, CVPR 2021
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Random directional vector #2

Closed brianw0924 closed 2 years ago

brianw0924 commented 2 years ago

Hi,

In the Random exploration section:

Could you explain why the random directional vector is sampled from R^{z*z}, where z = mn/3?

I guess /3 is because three dimension(x,y,z), but why R is z*z matrix?

and, delta = R - (R^T d) d, does it mean that R perform orthogonalization w.r.t d?

Thank you.

qkicen commented 2 years ago

Hi brianw0924,

(1) The size of one motion is mn, where m is the number of Dofs in one frame and n is the total frame number. A random directional vector sampled from R^{z*z} is to ensure the generated perturbations keep the same size as the motion. (2) yes

realcrane commented 2 years ago

It looks like the issue has been resolved. I will close it now.