Here’s another approach:
headslice transparency matte.c4d (772.7 KB)
Since it’s all being faked via transparency mask, this yields the cleanest result as it does no geo distortions. It also has ridiculously fast render times. Whereas the same render size and similar quality for other methods was anywhere from 30 to 90 seconds, this takes 1 second.
All good, but…
The masked edges come out quite janky regardless of how high object settings are cranked, so anti aliasing on render is a must.
The “bevel” is being faked by using the same flat luma shade for both the inside of the outer head, and the outside of the inner head. The illusion is broken if any diffusion, reflection, etc is used. Flat luma is ass I could get to work, thougu perhaps there’s a way to shade by distance from camera or something like that.
It only works with flat view as perspective would warp the relationship between the helix and head. Quite unfortunate since some other tricks I was looking to do rely on perspective.
Oh, and rotating the helix won’t move it as normal (or as seen in preview), so it has to be moved up / down.
This is certainly much easier and less problematic than other approaches… and MUCH quicker to render. I can live with the flat bevel coloring. My only issue is with being forced to do flat perspective to preserve the relationship between the camera, helix, and head. If that can be fixed, this approach may be ideal.
Only solution I’ve come up with so far isn’t exactly simple. To work properly in perspective, the transparent mask would have to exactly match the contour of the head (the exact intersection of the helix and skin). Furthermore, it would have to be done separately for the outer and inner head, and I’m not aware of a way of separately using two overlapping transparency masks int he same shot, so outer and inner heads would seem to need to be done separately and composited.
This isn’t simple either as the near portion of the head needs the outer head in front of inner, and the back portion of the head needs inner in front of outer, so there would perhaps need to be something like a plane bisecting the head that always faces the camera so the compositing order on the back half of the head can be switched.
That’s theoretically possible, but I’m not sure how to shrink wrap the transparency to the skin surface while retaining the helix’s shape (without again resorting to boole or mesh), and the compositing is kludgey at best.
Any other methods to allow perspective with masking approach?