> which I implemented for RenderMan

Cool, you work at Pixar? I've been working on a small hobby renderer [1] for a few years, and RenderMan has been a big inspiration!

[1] https://github.com/vkoskiv/c-ray

I used to until recently, but decided I was ready to try something new.

Glad you found RenderMan an inspiration. I had too when I was working on my own hobby renderer before joining Pixar! Yours looks very nice.

It seems like it's supposed to be "Pannini", after a painter (https://en.wikipedia.org/wiki/Image_stitching#Pannini), and that's what the original paper says.

But when the lead author spells it both ways in the same URL, and many software implementations use "Panini", it gets a bit confusing!

That's because historically it has been spelled both ways. I believe that even the artist himself was inconsistent. However, I'd read somewhere that he tended to sign his paintings with the single-n spelling, so that's what I went with for the plugin name.

He was probably very hungry, never think with your stomach!

Pannini Projection doesn't change occlusions though as described in the article.