# Automated Assessment Tool for 3D Computer-Aided Design Models
## 3 Proposed Approach
### Evaluation Method  
CAD model evaluation methods involve various techniques to assess the correctness and consistency of the model, including its geometry and topology. One the existing approaches is to compute the geometric properties of the model's NURBS surfaces, such as inverse evaluation to determine a 3D query point's corresponding UV parameter values [37]. There is also a method that involves the use of Model-Based Definition (MBD) and a Multi-Dimensional Attributed Adjacency Matrix (MDAAM) to identify and evaluate the local features of 3D CAD models, considering topological structure, shape, size, tolerance, and surface roughness [38]. Additionally, another paper describes an attempt to address the automatized evaluation of student 3D CAD models. The proposed solution involves using a feature-based design (FBD) approach. The evaluation is based on rules created by the teacher, specifying which elements of the FBD model must be present in the student model and assigning marks based on the conditions met [31]. The evaluation engine reads the CAD module data and generates a student report based on the evaluation results, providing a systematic and automated way to assess student models. Therefore, the evaluation of student CAD models is common practice in mechanical engineering education. This process helps assess the quality of a student's work and provides valuable feedback for improvement. To properly evaluate a given model, it is essential to establish clear criteria that will be used to assess the student's CAD model. So, creating a checklist of items or features that need to be present in the CAD model is a critical step. These items should be based  
Figure 1: General comparison process flowchart. on the reference model and project requirements, such as specific shapes, dimensions, assembly constraints, etc. Then starts the technical accuracy evaluation of the student CAD model. This includes checking the model's dimensions, tolerances, material properties, and whether it meets the functional requirements of the project or not. It is also important to evaluate the use of color, texture, and how well the model mimics the object's real-world appearance. If the given work involves assemblies, evaluating how well the student's model fits together is important to verify whether it shows a clear understanding of assembly principles. Ones the checklist is prepared the student's model can be compared to the reference model, item by item, using the pre-defined assessment checklist. Based on the comparison report generated while applying the proposed comparison process in this paper, the checklist that can be used will be mainly composed of the following questions:  
* Are the part's weight and overall dimensions (length, width, height) correct? * Are the part's shape and geometry (with precise angles, specific parameters) accurate according to the reference model? * Does the part look realistic (e.g., finish, color, texture)? * Is the material selection correct and are the material properties (e.g., density, modulus of elasticity) correct? * Are all necessary features (holes, fillets, chamfers, etc.) according to reference model? * Are the dimensions and positions of the features accurate and in agreement with the reference model? * Is the part correctly fitted and aligned with other components in the assembly (if applicable)? * Are all required assembly constraints or relationships correctly defined and used? * Are there any problems with interference or collision with other components in the system? The previously detailed checklist also needs to be translated into a concert evaluation method (Figure 2).