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Mastering
3D Studio MAX R3 |
Chapter 5
Organic Modeling
Featuring
- Understanding Spline-Based Modeling
- Shaping Bezier Splines
- Shaping NURBS Curves
- Modeling with Patches
- Modeling with Surface Tools
- Modeling with NURBS
- Subdivision Surface Modeling with NURMS
This chapter will familiarize you with the three main
organic modeling options in 3D Studio MAX: patch modeling, NURBS modeling,
and subdivision surface modeling. You will explore the advantages and
disadvantages of the different methods and use MAX Surface Tools to create
a model. This chapter will describe the different tools and approaches
available to each type of model and give you important pointers for successful
modeling.
Modeling Organic Forms
When modeling characters and other organic objects, you often need to
create smoothly continuous surfaces that can be edited easily. MAX offers
three very powerful options for organic modeling: patch modeling, NURBS
modeling, and subdivision surface modeling. These correspond to the three
types of model outputs mentioned in Chapter 4: patches, NURBS, and meshes.
MAX offers extra versatility by allowing you to convert between the different
outputs. NURBS and patch models can be converted to polygonal models and
then further edited with mesh tools. Meshes can be converted to patches
or NURBS and then edited with the corresponding tools and methods. You
are free to experiment with whatever works for you.
Choosing a
Modeling Approach
Developing a modeling style is personal. What works fabulously well for
one person will be a hair-pulling bundle of frustration to another. You
may find using loft deformations to be completely intuitive, for example,
while your co-worker finds them unreliable and prefers to move each vertex
with transform type-in commands.
As another example of choosing your approach to your modeling workflow,
consider just the number of ways you can access the sub-object selection
levels (Vertex, Polygon, and so forth). You can go to the Modify tab of
the Command Panel, click the Sub-Object button, and choose the sub-object
level you want from the drop-down list. You can also get there by clicking
the individual sub-object icons at the top of the Selection rollout. And
when you right-click any object in a viewport, the shortcut menu includes
the Sub-Object options, allowing you to navigate levels that way.
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| TIP You can
cycle between sub-object levels by pressing the Insert key.
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Multiply this example by the many thousands of commands in MAX, and you
begin to get an idea of the choices available to you in developing your
modeling style. You may like to use shortcut keys, and may assign your
own in Customize Ø Preferences. You
may use the right-click shortcut menus for almost everything. These, too,
can be customized. You may write MAXScripts to streamline your workflow,
use the Tabs in the Shelf Area, or make your own toolbars. You may prefer
to build a coarse form first and then add detail, or you may build a very
detailed nose and then build the rest of your character piece by piece
around it. Youll find the methods that work best for you.
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| NOTE In the
exercises in this book, we will sometimes stick to one technique for
a while, to keep things simple, and sometimes vary our technique,
to better acquaint you with the different methods available. We hope
this will help you discover the methods and workflow that best suit
you.
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One choice you have to make up front is whether you want to use reference
images or to model freestyle. This choice can depend upon the nature of
the project, too. If you are hired to model a specific jet plane, for
example, you will need to acquire accurate orthographic drawings and model
from those. In the examples in this chapter, we will use a freer style,
since we have no specific constraints and simply want to acquaint ourselves
with the various tools and methods.
Top 5 MAX Concepts
Move or Modify?: The Difference Between a Transform and a Modifier
What is the difference between a transform and modifier? A simple
enough question,certainly, and easy to answer in some cases. Then
why ask it? Its a good question because it forces us to consider
what we are doing with our geometry. Do you really know what you
are doing to your geometry?
Well, if you dont, or if you donХt know what we mean by that,
consider the following.
On the surface, the definition of this topic is self-evident. A
transform is the movement of your geometry from one location in
world space to another. A modifier is a change to your geometry
in object space. What about when you use the Move, Rotate, and Scale
transforms to modify a model? Well of course you are in Sub-Object
mode, right? You are just moving a couple of vertices around. Maybe
you are collapsing a couple of faces or even turning some edges!
But by working at the Sub-Object level, you are working at the
heart of the math that the engineers at Discreet have calculated
for you. And by transforming an object through space, you are multiplying
that small amount of math by however many vertices you have in your
model.
The difference is the order in which they occur. This is critically
important! According to the sidebar in Chapter 4, the dataflow tells
us that transforms are calculated after the modifier stack. Meaning
that, for example, if you have a cylinder with a Bend that moves
20 units in the Z axis, it would be calculated like this: The cylinder
is drawn in the view-port,the bend is applied, and the move is calculated.
Simple, right? But letХs consider a more advanced implication.
- 1. Create a box that has a length of 200
units, and a width and height of 80 units each.
- 2. Rotate the object 45 degrees in the Z
axis. Note the bounding box corner markers are still tight around
the box, indicating that the bounding box has been transformed(rotated)
in world space.
- 3. Now add a Xform modifier to the object.
(Xform is short for a transform in object space.)
- 4. Enter Sub-Object mode and rotate the Xform
gizmo 45 degrees in the Z axis.
This time notice that box has rotated just like before, but the
bounding box has merely expanded to accommodate the rotation. Even
though visually the effect is the same, the two are quite different
in terms of dataflow.
In the first example, the transform happens to the entire box.
This means the creation parameters, pivot point, and bounding box
information has all been reoriented. In other words, the entire
object was transformed in world space.
In the second example, the bounding box orientation information
is the same, but the box has been reoriented locally, within the
stack. In other words, it has been transformed in object space.
So when do I use one or the other? That depends; in
some situations, only one method is possible. There may be times
when you want to correct the orientation of objects in your scene,
and the only way to do this is to adjust the transform. On the other
hand, if you are doing any file exporting, you must certainly consider
using the Xform modifier to transform an object. This is because,
in many export formats, world transformations do not export; and
even when they do, each 3D program interprets transforms, especially
rotation, differently, so the results are unreliable.
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© 2000, Frol (selection,
edition, publication)
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