Positioning Geometry Actors in 3DVIA Composer

If you’re a veteran CAD designer getting to know 3DVIA Composer, you’ve probably already asked yourself the question, “Why doesn’t this tool let me maintain my CAD assembly constraints?”  There’s actually a very good reason – they’re going to be more hindrance than help.  3DVIA Composer allows you to create and move geometry actors (parts and assemblies), as necessary to show how products are assembled, regardless of how the models were built in the original CAD system.  The way a product is physically built is typically different than how the model was assembled in the CAD system.  Additionally, CAD designers often build assembly constraints into their models for simulation or analysis purposes that have no meaning outside Engineering.  By removing the CAD assembly constraints, users generating animations are able to more clearly communicate their ideas.

The most common question concerning 3DVIA Composer animations is, “How can I get geometry actors to move in a specific direction?”

To get the actors to move is a specified direction 3DVIA Composer gives you three methods, Translation, Rotation, and Free Dragging.  Free Dragging will allow an actor, or a selected group of actors, to move without reference to any other actors.  Translation mode will allow the actor(s) to move in a linear X, Y, or Z direction.  Rotational mode will allow the radial movement of the actor(s) about the same three axes.  The actor’s neutral coordinate system is normally in the center of the actor, so the linear and radial movements are from that set location.  To have the actor move relative to a selected edge or axis, hold down the ALT key.  The ALT key will allow you to select a linear edge to translate along or to use as an axis of rotation.  You can also select a circular or cylindrical edge to move the actors based on the center axis of that edge.  Being able to select edges and axes gives you the ability to create real movement when creating animations. For example, an entire door assembly can be put into a selection group and the selection can be rotated about the hinge axis to show the door’s movement. 

When loading CAD data into 3DVIA Composer, the application will import the 3D geometry with the components in the same exact relative location as they are in the original CAD models.  For example, when a model is imported from CATIA or SolidWorks, the geometry will look exactly the same in 3DVIA Composer.  However other assemblies and parts can be imported into the same file or created from within Composer.  3DVIA Composer will also allow you to create relationships between actors to get them in an exact location.  The object alignment tools on the Navigation menu give you several options to get models into position.  The point to point object alignment tool connects two vertexes of two different geometry actors.  Line (axis) to Line (axis), and Plane to Plane, can both be used to center a bolt to a hole and make the contact faces touch. You can connect other pieces of geometry by using Point to Plane or Line (axis) to Plane commands.  Always select the actor that you want to move first.  3DVIA Composer assumes that the first selection is the actor that needs to be positioned, so it will hold the second actor still while relocating the first actor.  Also note that the alignment tools in 3DVIA Composer only translate the actors to a new position, the tools will not reorient the actors.

Why is losing all the constraints from the CAD model good?

It may take more time to dissect and understand someone else’s CAD assembly constraints than it would to build your own constraints and positions.  Even modifying a solid model that was built by another person can have puzzling results.  Chances are not good that the way a product was designed is necessarily the way that it needs to be assembled or serviced.  So do yourself a favor, let go of your constraints and take advantage of 3DVIA Composer’s tools for positioning geometry actors.  Please contact us if you want help with 3DVIA Composer or any of these concepts.

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This entry was posted on Friday, January 22nd, 2010 at 7:25 am and is filed under Technical Tips, Technical Publishing, 3DVIA Composer. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.