[CAD note] NURBS in ACAD2011(!)
As I can see Autodesk are trying to insert all engineering tools into an AutoCAD (inc. NURBS modelling). The Mechanical Desktop has been killed, but I can see some guts from there in the AutoCAD 2011, while most of these tools were realized in the MDT(AutoCAD)14 more than ten (!) years ago. In general I like this tendency, I am just surprised why it was not possible to make it earlier.

http://www.youtube.com/watch?v=4yxGoIwRDdo&feature=relmfu
http://www.youtube.com/watch?v=0hlLIkXxIxk&feature=related

1. Solid Modeling:
3D modeling tools in AutoCAD 2011 have been updated to provide more flexibility and increased ease of use. The EXTRUDE, LOFT, REVOLVE, and SWEEP commands now allow you to select an edge or subobject for using as a profile or curve to create a new surface. You are no longer limited to using planar curves.
The Solid ribbon tab provides access to new Fillet Edge and Chamfer Edge solid editing tools. Both of these tools provide a preview prior to completing the operation and they support direct manipulation.

2. Surface Modeling:
In addition to 3D solid and mesh objects, AutoCAD 2011 offers two different types of surfaces: procedural and NURBS(!) (non‐uniform rational b‐spline). Procedural surfaces are associative and have history. NURBS surfaces are not associative and do not have history. Instead, they have control vertices that allow you to sculpt shapes in a way that is closer to how you would operate in the real world. You can use procedural surfaces to take advantage of associative modeling and use NURBS surfaces to take advantage of sculpting with control vertices. A typical surface modeling workflow might be:
- Create a model that combines 3D solids, surfaces, and mesh objects.
- Convert the model to procedural surfaces to take advantage of associative modeling.
- Convert the procedural surfaces to a NURBS model with the CONVTONURBS command to take advantage of NURBS editing.
- Check for imperfections and wrinkles with the surface analysis tools.
- If necessary, rebuild the surfaces to restore smoothness with the CVREBUILD command.

3. Surface Creation Tools:
AutoCAD 2011 enables you to create three new analytic surface types: Blend, Patch, and Network. A blend surface creates a smooth transition between existing surfaces using the new SURFBLEND command. You can specify how the blend surface flows at the edge that meets and touches the other surfaces using the grip menu options.
The new Patch surface tool enables you to close or “patch” an open, closed‐edge object. It generates a new patch surface for any bounding edge that is a closed loop. The new Network tool enables you to create a surface through a set of curves in the U and V directions. It is similar to the LOFT command but more streamlined and flexible. You can even choose a selection of curves that are not connected to one another. If you define the edges of a networked surface using edges from existing surfaces, the newly created surface will have additional grips enabling you to control the continuity condition between the newly created surface and its adjacent surfaces. The offset tool (SURFOFFSET command) is accessible from the Create panel of the Surface ribbon tab. It enables you to easily create a new surface by offsetting an existing surface.
You can turn on Surface Associativity prior to performing a Blend, Patch, or Offset operation, accessible from the Create panel of the Surfaces ribbon tab, to constrain the new surfaces based on the originating surfaces. For example, if surface associativity is enabled when you create an offset surface and a blend between the two surfaces, all three surfaces are associative. If you edit the offset distance, using the Properties palette or grips, the blend surface will update accordingly.

4. Surface Editing Tools:
AutoCAD 2011 offers a set of robust new surface editing tools to fillet, extend, trim, and untrim surfaces. You can create a fillet with a specified radius between two surface edges using the new Fillet tool (SURFFILLET command), available on the Edit panel.The new Trim tool, accessible from the Edit panel, enables you to create complex edges and holes in surfaces. You can use the Untrim tool (UNTRIM command) to untrim a trimmed surface.The new Extend tool (SURFEXTEND command), on the Edit panel, enables you to extend a surface by selecting an edge.The new Sculpt tool (SURFSCULPT command), accessible from the Edit panel, enables you to create a new solid object based on the enclosed volume of multiple intersecting surfaces.
The new Project Geometry tools (PROJECTGEOMETRY command) enable you to project geometry onto a surface creating a new line or spline on top of the surface. Unlike the existing Imprint tool, the projected geometry is not consumed by the surface. You can use the AutoTrim tool to specify whether surfaces are automatically trimmed when you project geometry. All of these tools are available in the Project Geometry panel of the Surface ribbon tab. You can convert from analytic surfaces to NURBS surfaces using the new Convert to NURBS tool(CONVTONURBS command) which is accessible from the Control Vertices panel on the Surface ribbon tab. Once an analytic surface is converted to a NURBS surface you can show/hide the control vertices via the Show CV and Hide CV tools (CVSHOW and CVHIDE commands) and use the gizmo to move the control vertices, reshaping the surface. Additional tools in the Control Vertices panel enable you to rebuild the control vertices (CVREBUILD) or add (CVADD) and remove (CVREMOVE) vertices. The CV Edit Bar, located on the ribbon, is a convenient tool that combines the CVADD, CVHIDE, and CVREMOVE functions.

5. Analysis Tools:
AutoCAD 2011 provides a set of analysis tools to help you understand the continuity between different surfaces that make up a global shape. These tools are available in the Analysis panel of the Surface ribbon tab. The Zebra tool enables you to analyze surface continuity by projecting parallel lines onto the surface. The Curvature tool displays a color gradient on the surface, enabling you to identify high and low areas of curvature. The Draft tool displays a color gradient on the surface, enabling you to determine if a model has adequate draft between a part and its mold. You can control the display and behavior for each of the analysis tools using the Analysis Options dialog box. The Analysis Options dialog box is accessible from the Analysis panel as well as from the 3D Modeling tab of the Options dialog box.

6. Mesh Modeling:
(NOTE: I cannot understand why they are keeping this ancient tool now - because I think this tool is suitable only for 3D MAX, but not for a CAD/CAM/CAE software.)
Mesh modeling functionality has been updated in AutoCAD 2011 to provide you with more flexibility and control. You can access the Mesh modeling tools from the Mesh tab when the 3D Modeling workspace is active.
The new Merge Mesh tool enables you to merge two or more adjacent faces into a single face.
You can use the Close Hole tool to close gaps in mesh objects by selecting the edges of the surrounding mesh edges.
The Collapse Face or Edge tool enables you to force vertices of surrounding mesh faces to converge at the center of a selected edge or face.
The Spin Triangle Face tool modifies the shapes of faces by rotating the edge that joins two triangular mesh faces.

7. Point Clouds
AutoCAD 2011 enables you to attach and display point clouds created from 3D scanning devices. You can access the new Point Cloud tools from the Insert ribbon tab.
You can attach a point cloud file (ISD or PCG) to an AutoCAD drawing in a similar manner to attaching other reference files.
With a point cloud file attached, you can create and edit drawing geometry by snapping to points. Adjust the point density using the Density slider bar in the flyout of the Point Cloud ribbon panel.
- POINTCLOUDDENSITY controls the percentage of points displayed at once for all point clouds in the drawing.
- POINTCLOUDRTDENSITY controls the percentage of points displayed during real‐time zoom, pan, and orbit.
- POINTCLOUDLOCK controls whether the lock property of the point cloud is set to Yes or No when a point cloud is attached.
- POINTCLOUDAUTOUPDATE controls whether point clouds are dynamically updated when transforming the point cloud or after zooming, panning, or orbiting.