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Mastering 3D Studio MAX R3

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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.


TIP You can cycle between sub-object levels by pressing the Insert key.

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. You’ll find the methods that work best for you.


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.

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? It’s 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 don’t, 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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