Intel® Distribution of OpenVINO™ Toolkit
Community assistance about the Intel® Distribution of OpenVINO™ toolkit, OpenCV, and all aspects of computer vision-related on Intel® platforms.




I am not able to understand the output format of the person-detection-action-recognition-0006 model. It says there is 8600 number of priors but actually, when I tried to run on the local machine I only got 8550, 50 are missing. Along with that, I am not able to detect the actions/bounding box as mentioned in the documentation.

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2 Replies

Hi Aptha,

The documentation says - 

num_priors - number of priors in SSD format (equal to 50x86x1+25x43x4=8600)

How did you compute num_priors as 8550? Can you elaborate?

A recommendation is to check the respective values during runtime by adding the watch on the variables.

Priors are pre-computed, fixed-size bounding boxes that match the ground truth.

I used the following command to verify the sample:-

./smart_classroom_demo -i classroom.mp4 -m_act intel/person-detection-action-recognition-0006/INT8/person-detection-action-recognition-0006.xml -m_fd intel/face-detection-adas-0001/INT8/face-detection-adas-0001.xml -m_lm intel/landmarks-regression-retail-0009/FP32/landmarks-regression-retail-0009.xml -m_reid intel/face-reidentification-retail-0095/FP32/face-reidentification-retail-0095.xml -l lib/ -al out.txt

Sample Output in out.txt file:-

frame_id: 8
      det_conf: 9.8083811998367310e-01
      label: 0
      rect: [ 446, 488, 178, 395 ]


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Hi Aptha,

According the reported network, it has two heads and 5 predefined “prior boxes”:

  • The first head is placed on top of the feature map with 50x86 spatial size. For this head, we select 1 prior box from the 5 predefined one. So, we have 50 (height) * 86 (width) * 1 (num priors for current head) = 4300 generated “anchor boxes”. It means that at each pixel location we generate the set of “anchor boxes” from the selected set of “prior boxes”.
  • Similarly, the second head is 25x43 spatial size and we select the rest 4 “prior boxes” from the 5 predefined one. So, the number of generated “anchor boxes” at this head is 25 * 43 * 4 = 4300.
  • Finally, the total number of anchor boxes is 4300 + 4300 = 8600

There is a difference between the terms “prior box” and “anchor box”.

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