Customizing Computer-Aided Design

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MIT researchers have devised a technique that “reverse engineers” complex 3-D computer-aided design (CAD) models, making them far easier for users to customize for manufacturing and 3-D printing applications.

Nearly all commercial products start as a CAD file, a 2-D or 3-D model with the product’s design specifications. One method that’s widely used to represent today’s 3-D models is constructive solid geometry (CSG), a technique where numerous basic shapes, or “primitives,” with a few adjustable parameters can be assembled in various ways to form a single object. When finalized, the compiled digital object is converted to a mesh of 3-D triangles that defines the object’s shape. These meshes are used as input for many applications, including 3-D printing and virtual simulation.

Customizing that mesh, however, is no easy task. For example, adjusting the radius in one portion of the object requires individually tweaking the vertices and edges of each affected triangle. With complex models comprising thousands of triangles, customization becomes daunting and time consuming. Traditional techniques to convert triangle meshes back into shapes don’t scale well to complex models or work accurately on low-resolution, noisy files.

In a paper presented at the recent AMC SIGGRAPH Asia conference, MIT researchers describe a system that applies a technique called “program synthesis” to break down CAD models into their primitive shapes, such as spheres and cuboids. Program synthesis automatically constructs computer programs based on a set of instructions.

MIT researchers have devised a technique that “reverse engineers” complex 3-D computer-aided design (CAD) models, making them far easier for users to customize for manufacturing and 3-D printing applications.

Nearly all commercial products start as a CAD file, a 2-D or 3-D model with the product’s design specifications. One method that’s widely used to represent today’s 3-D models is constructive solid geometry (CSG), a technique where numerous basic shapes, or “primitives,” with a few adjustable parameters can be assembled in various ways to form a single object. When finalized, the compiled digital object is converted to a mesh of 3-D triangles that defines the object’s shape. These meshes are used as input for many applications, including 3-D printing and virtual simulation.

Customizing that mesh, however, is no easy task. For example, adjusting the radius in one portion of the object requires individually tweaking the vertices and edges of each affected triangle. With complex models comprising thousands of triangles, customization becomes daunting and time consuming. Traditional techniques to convert triangle meshes back into shapes don’t scale well to complex models or work accurately on low-resolution, noisy files.

In a paper presented at the recent AMC SIGGRAPH Asia conference, MIT researchers describe a system that applies a technique called “program synthesis” to break down CAD models into their primitive shapes, such as spheres and cuboids. Program synthesis automatically constructs computer programs based on a set of instructions.