rendering fails: TypeError: 'NoneType' object is not subscriptable

[anilesec]

Thanks for making the obman_render code available.
I am trying to render multiple views of obman. I installed everything based on your well written instructions.

But when I launch the blender using the commands provided in GitHub page, I am getting an error message at thie line

File "./blender_hands.py", line 223, in run
segm_img = cv2.imread(tmp_segm_path)[:, :, 0]
TypeError: 'NoneType' object is not subscriptable

same errors for blender_grasps,py also

I would like to know if you had also encountered this error at any point of time.
It would be a great help if you could have suggestions or hints to solve this error, because even after spending more than 2 days I could not find the reason(may be because, I am new to blender)

Thank in Advance!
Hoping to hear from you.

[ThibaultGROUEIX]

I hit the same issue and had to downgrade opencv.
The [blender_path]/pip3 install -r requirements.txt installs opencv 4.4 which is not retrocompatible for some reason.

It triggers an issue with the linkage of libpgn I was not able to solve:

libpng warning: Application was compiled with png.h from libpng-1.5.13
libpng warning: Application  is  running with png.c from libpng-1.2.50
libpng error: Incompatible libpng version in application and library

Downgrading to 4.1.1.26 solves it.

[blender_path]/pip3 uninstall opencv
[blender_path]/pip3 install opencv-python==4.1.1.26

@hassony2 you may want to update the requirements
opencv-python>=4.1 --> opencv-python==4.1.1.26