XNECT terminates when people overlap

[sneheshs]

Hi Dr. Mehta/ XNECT Team,

First of all, great work with XNECT! I am a PhD candidate at the University of Maryland College Park. I was trying to use XNECT for a paper I am working on. I had a weird issue when there was an overlap of two people in a given frame. In this setup, I have footage of two people overlap and person 1's number of joints detected are less than 4 -- I think this issue happens then due to pnp constraint. Try/catch does not capture this issue as OpenCV catches it and terminates the call. Can you or someone on your team please help resolve this issue?

Steps to reproduce:
Place the attached frame in the images folder path ../../data/images (defined by images_to_load variable)
run XNECT/src/main.cpp

Possible error after function call:

(line193 at XNECT/extern/xnect/include/xnect.hpp)(inside function XNECT::processImg ) :: postCNNSecondNet(m_SecondNet->blob_by_name("pred_3d_pose_scale_root")->cpu_data(), m_ColorSized);  

Command Line output:

terminate called after throwing an instance of 'cv::Exception'
  what():  OpenCV(3.4.9) /root/opencv-3.4.9/modules/calib3d/src/solvepnp.cpp:754: error: (-215:Assertion failed) ( (npoints >= 4) || (npoints == 3 && flags == SOLVEPNP_ITERATIVE && useExtrinsicGuess) ) && npoints == std::max(ipoints.checkVector(2, CV_32F), ipoints.checkVector(2, CV_64F)) in function 'solvePnPGeneric'

Here is a sample frame:

Thanks for your help!

Best,
Snehesh