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Mesh vs. CAD

When it comes to 3D digital models, it can be a bit confusing to know which model or file type you need. The two primary types of models you will encounter are meshes and CAD files. In this article, we’ll break down the difference between both model types and explain how they are made and how they look and function. 

Mesh

3d-scanning-mesh-detailAppearance & Features

A mesh is a 3D model that is made up entirely of triangles that often number in the thousands or millions to create a complete model. These triangles are made by connecting data points that have been rendered on Cartesian coordinates (X, Y, and Z planes). The points serve as vertices, and once they have all been connected to their immediate neighbor, a full model is formed. For the mesh to work properly, it cannot be self-intersecting, meaning that no line, or edge, can pierce the face of another triangle. This type of model does not distinguish between different features, such as faces or holes, which is one reason why editing a mesh parametrically is very difficult compared to CAD. This model may also be referred to as a polygonal model.

How It’s Made

When a part is 3D scanned, the scanner records measurements in the form of thousands or millions of data points, called a point cloud. These data points become the vertices of the triangles once the software is told to convert the point cloud into a mesh by connecting the dots. A mesh may also be created manually, but this method is tedious and ineffective because an average low-resolution mesh will still have hundreds or thousands of data points.

Applications

Meshes can be used for several different purposes, including the following: 

  1. Reverse engineering – Meshes serve as a template for engineers to draw usable CAD of the scanned part. This is used to replace lost CAD, create CAD for legacy parts, and more. 
  2. Dimensional analysis