odd faces and inversions rendered

Start with default cube
NUMPAD 1 front view

TAB edit mode

KEY W KEY 3 Percentage 500 (subdivide smooth)

Select left and right vertex (points)
KEY S KEY X -0.7 ENTER ( negative numbers, not typo)

Select top and bottom vertex (points)
KEY S KEY Z -0.7 ENTER

MUMPAD 3 side view
Select left and right vertex (points)
KEY S KEY Y -0.7 ENTER

TAB leave edit

KEY Z shade mode
Now you have a symmetrical spiked object. I have recalculated the normals but
the render still shows odd faces and inversions.
Does anyone know why?

KEY S KEY X -0.7 ENTER ( negative numbers, not typo)

i’m having a hard time putting this kind of description into a picture. could you put up a screenshot?

Yes. This spiked object looks good but it’s a pure mess :wink: It’s full of “inverted” faces, intersecting faces, etc.
I mean, the side of a face that is outside on one part of the object is inside the part of the other.
Blender can’t guess what faces to display as “outsides” and what faces to display as “insides”.

ah, kaleidescope modelling, as endi dubbed it.

.
I mean, the side of a face that is outside on one part of the object is inside the part of the other.
Blender can’t guess what faces to display as “outsides” and what faces to display as “insides”.[/quote]

And is unable to correct normals for that reason.
I understand, thanks