3D Model Defeaturing

The next release of Open CASCADE Technology (7.3.0) will include the new algorithm intended for removal of the selected features from the model. The features that can be removed include holes, protrusions, gaps, chamfers, fillets etc. The defeaturing algorithm can be very useful in different contexts:

• Model simplification for numeric analysis, display on mobile devices, etc;
• In the direct modeling concept where the history of operations is unavailable;
• Removal of the proprietary details of the model before sharing it with others;
• Fixing the certain defects in the model, e.g. filling the gaps, holes etc.

The removed features are filled by the extension of the adjacent faces, thus no unexpected parts should appear in the result. Here are few examples of how ANC101 model can be “defeatured” with the new tool:

Removing fillets:

Removing the gaps on the left side and on the back:

Removing the top face, so that the back and inclined faces are connected:

Sometimes, it is necessary to work step by step to remove the certain features. For instance, you want to remove the front face and prolong the inclined one to the bottom face:

In this case, the algorithm will be unable to remove the face, because it does not know how to handle the cylindrical holes:

So, the first step here will be to remove these holes, and only then remove the front face:

The algorithm is also able to work on the collection of solids. For example, you have a compsolid consisting of two solids:

What if you need to fill the gap on one of these solids, keeping the compsolid structure? With the new tool this can be accomplished really easy - just select the faces where the gap should be filled and perform defeaturing:

You can actually remove the whole gap if necessary - the shared face will be extended to separate the solids:

The Defeaturing algorithm is protected from incorrect input data. Thus, if you have accidentally selected the wrong faces, the tool will just warn you that the selected feature cannot be removed, and will continue with other features. For instance, it is impossible to remove the left face of the ANC101 model, because the opposite faces adjacent to that face are not going to be intersected:

The Defeaturing algorithm does not modify the input shape, it creates the new shape as the result. It also supports the history of shape modifications. These two factors make the algorithm safe to use and easy to integrate into an application. For the implementation details on the new algorithm and more examples of its usage, please refer the corresponding chapter in the documentation - 3D Model Defeaturing. The development of the new algorithm was supported by Sony Global Manufacturing & Operations Corporation.