CHAPTER 02: MAX and NURMS

Understanding NURMS

In this application, a car body/components we need a smooth surface, often ending on a small rolled edge, and often creases through the body styling. If NURMS make objects all soft and rounded, how to we make sharp edges? By increasing the mesh at the points that need sharpening, we create tension. Like so:

2b: The two cubes in the top view port are the same size, the left has greater detail on the edges, when the SAME meshsmooth modifier of 2 iterations is applied to both, the difference is obvious

Here the NURMS are trying to touch the centers on the faces, but the angle is too tight so it creates a sharper edge. Two faces at a perpendicular angle will create an almost perfect rounded edge, Three or more will make it more accurate, it's up to your discretion as to where it needs to be accurate, and where it just needs to be rounded.

For example, in the edges of body panels, where the metal rolls around, putting a small tight edge that butts perfectly to another tight edge can make all the difference in realism, as where as a big roll on the bonnet for example, will need more faces, further apart, to look smooth and "un lumpy". It is sometimes better for the computer to figure out large curved surfaces rather than you try and make them.

2c: A high detail is used where needed, especially on the corners, the rest of the mesh is relatively simple

Now for the "4 sided" aspect of NURMS. Possibly the biggest challenge for the newcomer to NURMS, is the fact that NURMS only really understands 4 sided faces. Not quite as daunting at first glance, but the further you get into a model, the more complex it becomes. NURMS can use triangles, and 5+ sided faces, but generally, the results are far from what is desired. Though there ARE "work-around's".

Rather than re-invent the wheel, check out http://maxrovat.sns.hu/subdiv/ which explains NURMS or Subdivision modeling better than I can, but I'll give a general over view of what I've experienced directly concerning modeling a car.