"I start my students in Rhino," says high school teacher Phil Noble, "because they can begin producing models in a fraction of the time that it takes them to do the same thing in other programs." His students then export their models and pull them into 3ds max or Lightwave 3D for animation or rendering.
By default, the Rhino screen opens onto four viewports-Top, Front, Right, and Perspective. A right-click on any viewport name brings up the most complete context menu we've seen, letting you set most major viewport features. In Rhino, the majority of tools and buttons have both a left-click and a right-click command. It's no surprise, then, that you can move around any viewport just by dragging with your right mouse button.
Each viewport has its "construction plane," the base that is represented by the grid of that viewport. By default, the Perspective-viewport construction plane is the same as the Top viewport's plane. The construction plane is a viewport-dependent base for drawing and building your model's geometry. The cursor always moves on the construction plane, although you can force all viewports to assume the same construction plane as your active viewport.
You can place a background image in a viewport to aid with layout or scale. Although Rhino will not render background bitmaps, you can create a rectangular plane and assign a bitmap to that plane, which then will render. You can move and resize viewports, create new ones, rename them, or recall a viewport you've previously defined.
Rhino represents all lines, circles, and free-form curves as NURBS curves. NURBS surfaces, then, are smooth surface patches between those curves, instead of polygon meshes.
Rhino offers many ways to construct those surfaces. You can create a surface from three or four points or from the curves that form the sides of a surface (as in the roof of a dwelling), or by lathing (revolving a profile curve about an axis to create a wine glass), extruding a curve, or sweeping a curve along a rail. Rail Revolve creates a surface by sweeping one end of a profile curve along a shaping curve (as in lathing), while keeping the other end fixed.
Loft "with straight sections" creates a surface with creases (for an accordion), while Loft "normal" creates a smooth surface. Rhino can "loft" between curves that have different numbers of points. Or it can create a surface based on grayscale values of the colors in an image file, where lighter colors make mountains and the darker ones valleys.
Most 3D solids, including primitives, are actually polysurfaces that enclose a volume. So Rhino's primitives include the usual box, cone, and cylinder, plus a paraboloid (satellite dish), pipe, or torus (life preserver). You can extrude any of them (to make a torus into a pipe), or combine solids—using Boolean logic—to join them, by adding or by subtracting one shape from another, accepting or rejecting their intersections. You can create two or three-dimensional text from TrueType fonts in the form of curves, surfaces, or solids.