Many operations that are allowed on mesh, spline, or shape objects in Autodesk VIZ are not allowed on linked AutoCAD geometry, and other operations behave differently.
The following operations are not allowed on linked geometry:
If you must perform any of these operations, you must either do them in AutoCAD or else bind the drawing data to Autodesk VIZ, which breaks the link back to AutoCAD.
You can apply modifiers to linked AutoCAD geometry and these modifiers will persist when you reload the geometry. This can be a very powerful way to intelligently manage your design intent, but it can also lead to some unexpected results, especially when using topology-dependent modifiers.
“Topology-dependent” simply means that the modifier is relying on the particular arrangement and number of faces and vertices that comprise the mesh representation of the object. It is common, for example, for the modifier to cause an action to be performed on the nth element it encounters, say the “twelfth” face or the “fourth through the twentieth” vertex. It is easy to perform edits on the base object in AutoCAD that would cause the definition of the nth element to change, which would result in the modifier yielding unexpected results when the drawing is reloaded in Autodesk VIZ.
Not all modifiers are topology-dependent. When you attempt to use a topology-dependent modifier on linked AutoCAD geometry, a warning dialog is displayed that gives you an opportunity to continue or abort the operation.
When you use modifiers on linked AutoCAD objects and blocks, remember that the VIZBlock object you see in Autodesk VIZ does not contain any geometry directly; applying modifiers to VIZBlocks will never have any visible effect. Instead, apply modifiers to the component objects below the VIZBlock in the Autodesk VIZ object hierarchy.
You can copy actively linked objects in Autodesk VIZ; the copies are automatically converted to editable mesh objects. If your selection contains several objects that instance another object, the resulting copies also instance the same object.
However, it is recommended that you do not instance or reference actively linked objects, as this can introduce instability to the scene.