Weird results for rendering face

[zhipeng-fan]

Hi! Thanks for sharing this wonderful work! I tried to use it to render the face models but I obtained a weird rendering for the BFM. Basically I observed that some parts (nose) are partially transparent and there is a black border around the border of the face. I am wondering is that normal and if not, how to properly use the soft rasterizer?

I attached the rendering results for your reference.