I was able to replicate the issue
From 4D menu, do an "edge first" rotation
Select a green cell
Look at selected cell
Hide the cell

the result is not the same at all, and actually not as "clean"
https://i.postimg.cc/vDwJQMb2/windows-math-uwaterloo-ca-2019-01-07-13-53-26.png

Thank you for your patience. For some weird reason, quitting the program, restarting it, and then following these steps made it work.

Benoit

Thank you Robert, I really appreciate your patience.

I hid all but the green cells, and I tried with quite a few of the green cells. I attach here two trials. None were successful in getting me anywhere near the wikipedia image. I must be doing something wrong.

https://i.postimg.cc/rKvxz1JM ...

Thanks Robert.

This provide me lots of different projections, but I am not able to replicate the simple image for the 333-Gidpixhi I can find on Wikipedia, and neither am I able to get the other reflections. It is possible the author of that imagine has better knowledge of these Coxeter planes than ...

Good day everyone

obviously, someone has succeeded in using Stella to produce the projection on Coxeter planes of various 4D polytopes, including the omnitruncated 120-cell (333-Gidpixhi in Stella's database). See indeed this wikipedia page: https://commons.wikimedia.org/wiki/File:120-cell_t0123_H3 ...