Automatic Person Identification in Camera Video by Motion Correlation

Algorithm 1

Patch tracking and motion estimation.

  Variables

   𝑝𝐷𝑒𝑠𝑐: patch descriptor, 𝑝𝐷𝑒𝑠𝑐={𝑖𝑑,𝑓𝑟𝑎𝑚𝑒𝑆𝑡𝑎𝑟𝑡,𝑓𝑟𝑎𝑚𝑒𝐸𝑛𝑑,𝑐𝑒𝑛𝑡𝑒𝑟,ℎ𝑖𝑠𝑡}.

   𝑝𝐷𝑒𝑠𝑐𝑠: an array of patch descriptors.

   𝑝𝐶𝑜𝑢𝑛𝑡: patch descriptor counter, initialized to zero.

   𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥: frame counter, initialized to zero.

   𝑖𝑑: the ID of a patch.

   𝑓𝑟𝑎𝑚𝑒𝑆𝑡𝑎𝑟𝑡,𝑓𝑟𝑎𝑚𝑒𝐸𝑛𝑑: frame index of first and last appearance of a patch.

   𝑐𝑒𝑛𝑡𝑒𝑟,ℎ𝑖𝑠𝑡,𝑎𝑐𝑐𝑠: center and color histogram of a patch.

   𝑠_thr,𝑑_thr,𝑎_thr: thresholds for histogram similarity, patch distance, and patch area, 𝑎_thr≥0, and 𝑑_thr≥0,0≤𝑠_thr≤1.

  Procedure

(1) Grab a video frame

   𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥=𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥+1

(2) Optical flow estimation

(3) Background subtraction

(4) for Each patch in current frame do

(5) Calculate 𝑝𝐴𝑟𝑒𝑎,𝑝𝐶𝑒𝑛𝑡𝑒𝑟,𝑝𝐻𝑖𝑠𝑡,𝑝𝑊𝑖𝑑𝑡ℎ

(6) If  𝑝𝐴𝑟𝑒𝑎<𝑎_thr  then

(7)  continue

(8) end  if

(9) 𝑝𝐷𝑒𝑠𝑐𝑠^∗=0/

(10)  for  all  𝑝𝐷𝑒𝑠𝑐∈𝑝𝐷𝑒𝑠𝑐𝑠  do

(11)   if  𝑝𝐷𝑒𝑠𝑐⋅𝑓𝑟𝑎𝑚𝑒𝐸𝑛𝑑+1==𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥  and  𝑠(𝑝𝐻𝑖𝑠𝑡,𝑝𝐷𝑒𝑠𝑐⋅ℎ𝑖𝑠𝑡)≥𝑠_thr  then

(12)    𝑝𝐷𝑒𝑠𝑐𝑠^∗={𝑝𝐷𝑒𝑠𝑐}∪𝑝𝐷𝑒𝑠𝑐𝑠^∗

(13)   end  if

(14)  end  for

(15)  𝑑_min=𝑑_thr∗𝑝𝑊𝑖𝑑𝑡ℎ,𝑝𝐷𝑒𝑠𝑐_min=𝑛𝑢𝑙𝑙

(16)  for  all  𝑝𝐷𝑒𝑠𝑐∈𝑝𝐷𝑒𝑠𝑐𝑠^∗  do

(17)   𝑑_𝑝=𝑝𝐶𝑒𝑛𝑡𝑒𝑟⋅𝑥−𝑝𝐷𝑒𝑠𝑐⋅𝑐𝑒𝑛𝑡𝑒𝑟⋅𝑥

(18)   if  𝑑_𝑝<𝑑_min  then

(19)    𝑑_min=𝑑_𝑝,𝑝𝐷𝑒𝑠𝑐_min=𝑝𝐷𝑒𝑠𝑐

(20)   end  if

(21)  end  for

(22)  if  𝑝𝐷𝑒𝑠𝑐_min is 𝑛𝑢𝑙𝑙  then

(23)   𝑝𝐷𝑒𝑠𝑐_min={𝑝𝐶𝑜𝑢𝑛𝑡,𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥,𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥,𝑝𝐶𝑒𝑛𝑡𝑒𝑟,𝑝𝐻𝑖𝑠𝑡}

    𝑝𝐷𝑒𝑠𝑐𝑠=𝑝𝐷𝑒𝑠𝑐𝑠∪{𝑝𝐷𝑒𝑠𝑐𝑠_min}

    𝑝𝐶𝑜𝑢𝑛𝑡=𝑝𝐶𝑜𝑢𝑛𝑡+1

(24)  else

(25)   𝑝𝐷𝑒𝑠𝑐_min⋅𝑓𝑟𝑎𝑚𝑒𝐸𝑛𝑑=𝑓𝑟𝑎𝑚𝑒𝐼𝑑𝑥

     𝑝𝐷𝑒𝑠𝑐_min⋅𝑐𝑒𝑛𝑡𝑒𝑟=𝑝𝐶𝑒𝑛𝑡𝑒𝑟

    𝑝𝐷𝑒𝑠𝑐_min⋅ℎ𝑖𝑠𝑡=𝑝𝐻𝑖𝑠𝑡

(26)  end  if

(27)  Calculate and save vertical acceleration for 𝑝𝐷𝑒𝑠𝑐_min

(28) end  for