Nostril glow is the result of setting up shadows to miss something as small as a nostril.

This can multiple ways, but the two most common being:

1. Depth-mapped shadows, plus a small shadow map dimension, plus a lot of scene to cover with the shadow map.

2. Depth-mapped or raytraced shadows, plus having your shadow min bias too high.

As always, if you want to know something about topic X, go to rendo search, enter X in the search text, enter "bagginsbill" in the field to search for a specific user. Example results:

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2765271&ebot_calc_page#message_2765271

Which will take you to two more posts by me on the subject.

Or

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2753785&page=30#message_3405687

There are more - probably hundreds by now. It is an eternal topic I guess.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)