Definition of Rendering in Autocad

by Nancy Fulton

Autodesk's AutoCAD is the world's leading computer aided design application, with more than a 50 percent market share in the U.S. and higher rates of use worldwide. Designers use AutoCAD to create 3-D models of objects and environments and to produce images based on that 3-D geometry.
The process of generating a shaded image of how geometry might look under a given set of lighting conditions, and based on a given set of materials, is called "rendering." Architects frequently provide rendered images of buildings to their customers as part of the design process. Mechanical designers often provide rendered images of components prior to producing them. The tools and techniques used to create rendered images vary from version to version of AutoCAD, as does the quality of the images rendered, but there are some general principles that always apply.

Creating 3-D Geometry

AutoCAD features many tools for creating 3-D geometry. Some tools let you convert 2-D geometry into 3-D geometry. For example, you can change the 2-D lines that define walls in an architectural floor plan into 3-D walls simply by changing the "thickness" property of the walls. Other tools, like REVSURF and EDGESURF, let you define the skin of a 3-D object. By combining these thin surfaces you can define almost any object in 3-D. AutoCAD's solid modeling tools let you define objects with mass. This is most appropriate when you want to construct a mechanical object you plan to build. The 3-D modeling tools designers use in AutoCAD vary from project to project and designer to designer.

Applying Materials

Once you create a 3-D model, you must apply materials to it to specify what it will look like when you render images of it. In some cases, you may elect to assign a white plastic or steel material to your objects so the geometry is easy to see. This is most common for mechanical applications. In other cases you may elect to use scanned images of brick or stone to create photorealistic materials. This is commonly done by architects and interior designers. All recent versions of AutoCAD come with material libraries and allow you to create your own materials if desired.

Lights and Cameras

Once you've created a 3-D object or environment, then assigned materials to it, you need to illuminate it by specifying the location from which its rendered image will be generated. AutoCAD provides several illumination options. Early versions of the application offer users omni and spotlights. Omni lights cast light in every direction. Spotlights can be aimed like flashlights. Later versions of AutoCAD let users select a date, latitude and longitude to create a sun system in the drawing. This allowed designers to render an architectural environment based on a given day and time during the year. Most recently, Autodesk has added the ability to create indirect, diffuse lighting in drawings. This, when rendered, looks most photorealistic in most cases. Once the lights are placed, you usually position a camera or create a camera view from which you render the scene. This will create an image you can import into a document file as part of a proposal or place on a website as part of your marketing efforts.

Right Tool for the Job

Image rendered from 3ds Max. Sourced from the Complete Support website.

AutoCAD provides fairly rudimentary rendering tools. If you need to create truly photorealistic images and animations of your objects and environments, consider looking at Autodesk's other products, like Inventor and 3ds Max.

Learning More about Rendering

The Autodesk website provides a host of tutorials and resources that can help you learn to render in AutoCAD and in other applications. The site even provides trial versions of the software to experiment with. Taking time to master AutoCAD's 3-D modeling and rendering tools is a great investment for most designers. It makes them easier to employ and more effective at presenting their work to their peers, employers and customers.

Support for Older Versions of AutoCAD

If, like many AutoCAD users, you are not using the latest version of the application, you may have to look for guidance on how to use AutoCAD's 3-D modeling and rendering tools online. Amazon.com is a great resource for books and training materials that support older AutoCAD releases.

Hands-on Training

If you find learning AutoCAD's 3-D modeling and rendering tools too difficult on your own, you will find many local colleges, universities and trade schools offer courses in 3-D modeling and rendering as part of their curricula. AutoCAD user groups also provide guidance, and may provide consultants, who can help you through your first projects.

About the Author

Nancy Fulton is a professional writer with more than 20 years experience writing articles, books, business plans, marketing materials, website content and training products for schools and fortune 500 firms. She has also taught for UCLA and produced multiple films. As a serial entreprenuer she has worked in many industries and with a variety of government agencies.

Photo Credits

  • photo_camera A rendered table created in AutoCAD. Sourced from the Complete Support website.