1. Surface quality requirements for 3D models of reconstructed products: Surface quality is mainly divided into A-class surfaces, B-class surfaces and other surfaces with lower requirements; A-class surfaces require that the transition between surfaces must be continuous in curvature, which is mainly used for products with high appearance requirements, such as automobile body outer panels and household appliances outer surfaces. Class B surfaces require tangent continuity, which can generally meet the requirements of most products for contours, such as automobile interior parts and automobile chassis sheet metal parts. Other surfaces with lower requirements are mostly used for error analysis.

2. It meets the functional requirements of the product. Functional requirements are the basic requirements of products. Before reverse design, designers need to analyze the mechanism and structure of products according to their own experience or related product information, so as to know ourselves and ourselves.

3. The product meets the requirements. Reverse engineering is a design process, and the designed sample product is only a part of the whole machine, and there will be a matching relationship with its matching parts. Therefore, the structural design of the joint between reverse product and existing peripheral parts will affect the success or failure of a reverse design. Therefore, in the process of reverse design, the precision of mating surface must be ensured to meet the assembly requirements.

4. Process requirements of products. Design and processing are two closely linked links. Each product has its own production technology, and the designed products may not meet the requirements of the processing technology, so designers should have a certain understanding of the production technology. Reverse design process can better understand and absorb the processing technology of product samples, and avoid the failure of model reconstruction caused by missing details.