Introduction
Within the CAD world of surface modeling today, exist two traditional approaches to surface creation and modification. Freeform surfacing and parameter driven surfacing or explicit modeling and feature based modeling.
These two approaches have for a number of years been the industry standard for surface modeling, with the parametric (feature based) modeling being the more recent of the two. Each approach has its advantages and its disadvantages.
With free form (explicit) surface modeling, you can quickly generate geometry without the need to maintain any history to how the geometry was created. You have more control over the quality of the results, but modification to the geometry however is usually more cumbersome should the shape require a significant change (e. g. if fillet radii change from 5 mm to 10 mm). In most cases the user is required to start again. With parametric (feature based) surface modeling, you create geometry from a number of inputs and parameters. These inputs can be curves and the parameters are usually components such as a length value or a radius value. The advantage here is that should one of the inputs or parameters require modification, the feature result does not lose its history. Thus rapid changes to geometry specifications can be achieved with minimum effort.
Modification to the aesthetical shape of a surface feature is very difficult in some cases, as it is very difficult to replicate an aesthetical design intent from a stylist through a few parameters. Which is why the explicit modeling approach remains the main solution today in achieving this requirement.
With these two approaches, many companies try to avoid mixing them during their design creation, as although each approach has its benefits, different users skills are required to work within the two worlds. Usually the more aesthetic surface shape creation is performed in the explicit world, and the more engineered surface creation is performed in the parametric world.
ICEM Shape Design introduces a new paradigm shift in surface modeling approaches by bringing these two worlds together by introducing the concept of Feature Modeling.
What do we mean by Feature Modeling?
The 'Feature Modeling' concept within ICEM Shape Design lets you through an interactive method modify the geometric element of the feature, whilst it continues to remain a feature.
You are still able to create and modify the inputs and parameters of a feature result in the usual way, but now with the added advantage of being able to directly modify the geometry by its control points. i. e. explicit modeling.
When you wish to perform 'Feature Modeling' on an existing geometric feature element, the general concept locks or freezes the feature and any pre-defined parameters. Thus allowing you to perform local control point modifications.
Depending upon the feature type, some parameters and manipulators are still offered to allow to continue making parameter driven modifications. When modifications are complete, the feature is stored in the data model (CATPart) in the modified state.
