So how do people determine how many segments are needed when making a shape.

Let’s say you were to create a human/biped out of a box, how would you know how many segments (length, width, and height) are needed?

Whenever I’m following a tutorial they tell you how many segments are needed but they never explain why/how they get that number.

By the time I realize that I need more or have too many segments it’s too late. (Well it’s not too late but I’d like to know)

3DS Max 2011
Windows Vista 32 Bit
Dell XPS M1530
Intel Core 2 Duo CPU T5550 1.83 GHz
2 GB of Ram

If you were writing such a tutorial, how may segments would you use? How many times would you redo (follow) the entire tutorial checking and refining it each time? Many, many times is probably the answer - the final set of values presented to the reader may well have been refined many times before the exact number for that specific tutorial was arrived at.
They are, after all, just a starting point - easy enough to add or remove loops of edges later if the need arises - roughly equivalent to increasing or decreasing the Segments you started with.

Max 4.2 through 2013.
XP-64 (SP2)
NVidia 9800GTX-512 (Driver 266.58).
Core 2 Quad Q6600 2.4GHz, 8Gb Ram, DX9.0c.

Would adding more segments cause more rendering time?

Also instead of creating another topic, would Spline/Lathe Modifier be a good way to create a human head? And what I mean is I’m pretty good at using splines and I can create a human head this way but I was wondering if it would be orthodox/professional to create a human head/biped in general this way.

3DS Max 2011
Windows Vista 32 Bit
Dell XPS M1530
Intel Core 2 Duo CPU T5550 1.83 GHz
2 GB of Ram

Generally speaking adding more segments will increase render time because you are increasing your overall poly count; however, that all comes down to proper scene management & the importance of the LOD (level of detail) of the shot.  Anyway, that’s again something you just kind of get a feel for.

Personally, I would not use a Lathe modifier to create a head; however, a head could be created with splines & surfacing techniques; although, for me that method is fairly dated & tedious.  It’s kind of like Michele71 suggested, each artist has his or her own method of creation that works for them - you just have to find your niche.  Personally, if I were creating a head I would probably choose to box or strip model.

Chris Robinson
http://www.supercoonstudios.com (Under Development)
3ds Max 2011
Dell Precision 690, Intel Xeon Dual Quads @ 2.66 GHz, Dual NVIDIA Quadro FX4500s, 12 GB RAM, Windonws 7 x64