Q: How did you approach building the model of the De Tomaso
Mangusta sports car?
A: The Mangusta model was done for a British Motors project back in `99.
It was for a QuickTime VR rotation of the car on their web site. As you can
imagine, that made it a little harder, because the entire model had to look
correct from every angle; there wasn't any way to hide mistakes. My job
was to build the model, and then rotate the camera around it, making a
render at every 10-degree increment. The QuickTime VR software was used
to combine the rendered frames and enable the user to interactively rotate
the car to any angle.
I started the project trying to figure out which modeling technique was
going to give me the flexibility and power needed to create the ultra-fine
curves that car modeling requires. I considered three different approaches:
NURBS, patch modeling, and polygonal "box modeling" combined with
subdivision surfaces. Although NURBS lends itself very well to creating
aerodynamic surfaces, I like to put the mesh detail where it is most
required and leave other areas less complex. NURBS requires hulls and CVs
to completely enclose the entire object, thereby adding complexity where
it is not needed.
Patch modeling seemed like the way to go at first, and I went as far as mod-
eling the entire back bumper as a patch before I realized that I needed an
approach that would allow me to get even greater control over the final
look. When you're working with a very detailed object, and each patch-
modeled vertex has a Bezier spline that needs to be tweaked, modeling can
quickly get very slow and cumbersome. So, I scrapped the patch-modeling
route and went with a solution that was something of an unknown for me:
box modeling. Although I had used box modeling before, I had never
attempted anything of this scale and complexity.
Let me take a moment to explain the theory behind box modeling and
subdivision surfaces. The reason that it's called box modeling is because
you usually start with a cube and then start extruding and editing faces to
create the form you want. Of course, you can start with any primitive that
best represents your object; sometimes I even start with just a single poly-
gon, and then pull and clone edges to create the hull.
Polygons are inherently flat, making smooth, organic objects very difficult
to construct. The only way to get a polygonal object to look truly curved
is to have each poly about one pixel in size; not something you could
do by hand. What subdivision surface tools--such as the Mesh Smooth
3 D G
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