# Automated Assessment Tool for 3D Computer-Aided Design Models
## 3 Proposed Approach  
### Comparison Process  
The SolidWorks feature manager is a key window within SolidWorks, a widely used piece of industrial CAD/CAM software (Autodesk Fusion 360). It enables users to manage features and operations applied to a 3D model. Essentially, the feature manager in SolidWorks provides the following features. First, it provides a hierarchical structure for organizing the properties of the model. Users can easily visualize and manage the sequence of operations applied to the model by viewing features in a tree-like structure. It also provides a historical view of the features that have been applied. Each feature is listed chronologically, reflecting the order of their creation. This allows users to track operations and make changes easily. Another important aspect of the feature manager is its interactive nature. By selecting, reordering, or changing the parameters for each feature, users can interact with the model's features. Editing in the feature manager is instantly reflected in the model geometry. The management of relationships between features is also handled by the feature manager. To maintain model consistency during subsequent modifications, it allows users to define geometric relationships, constraints, and parametric relationships. Feature properties such as dimensions, tolerances, and materials are also visible and accessible in the feature manager. This makes it easy to manage and update related information within the model.  
To summarize, the SolidWorks feature manager is a unique window that allows users to visualize, organize, and modify the features of a 3D model in a hierarchical manner. Its intuitive approach simplifies the process of designing and modifying models by facilitating feature operations and property management. Thus the authors think it is possible to benefit from this feature manager as it can access the needed data [36].  
The main idea of this paper is to help teachers evaluate their students during CAD courses in an objective manner. Therefore, the feature manager will be useful to access both the student CAD model and the reference CAD model data. Then, the comparison process begins, which is mainly divided into four main steps, as mentioned in the flowchart shown in Figure 1.  
1. General comparison: As a first step, a general evaluation of the model is performed. An overview of the model's general properties is necessary to decide whether the model is correct or needs some corrections. If the model being evaluated is identical to the reference model, then the mass and the center of gravity must be the same. At the second stage, the material properties and the model parameters (if they exist) must also be identical.
2. Feature-based comparison: The feature data of both models have to be retrieved. The extracted features will then be compared in a two-by-two manner. Two identical features must have the same size, orientations, dimensions, and proprieties.
3. Geometry- and topology-based comparison: to decide about the similarity of two models a geometrical and topological comparison must be done. Two identical model have the same coordinate system, same faces, edges and vertexes.
4. Checking relationships and dependencies: Actually, two models can have the same topology, geometry, and features but never coincide because of a wrong constraint or a missed relationship. That is why the dependencies, relationships, and constraints must be carefully verified.