Computer-Aided Design Software: What Are They?

Computer aided design

Every discipline of engineering relies on a variety of software products to assist them with design, evaluation, and management tasks. Computer-aided design (CAD) software is one of the most commonly used engineering program categories and is used in nearly all branches of the engineering profession.

History of Computer-Aided Design Software

At its roots, CAD software was a direct analog of drafting functions: to create two-dimensional design prints. The output prints were essentially identical to those previously created by draftsmen. The proliferation of desktop personal computers in the 1980s allowed companies such as Autodesk to develop CAD software and market directly to engineering companies.

AutoCAD was first released by Autodesk in 1982, and rapidly became the most widely used CAD software package in the world. Even today, AutoCAD is still the primary 2D design program, used by engineers and architects.

Evolution of Computer-Aided Design Software

CAD software has evolved as computing power has increased since the 1980s. The expanding processing power has allowed software developers to include more functionality and performance in their products. The greatest leaps in CAD software evolution can be grouped into two categories:

  • Integration with Other Functions – While the early CAD software packages were basically computerized drafting, today’s CAD programs seamlessly integrate with a variety of other engineering functions, including computer-aided manufacturing (CAM), finite element analysis (FEA), product lifecycle management (PLM), and many other functions. The CAD software is now just the center of a network of design functionality.
  • Migration from 2D to 3D Design – The second significant evolution in CAD software was the development of 3D design software systems, led by Parametric Technology Corporation’s (PTC) release of Pro/ENGINEER in 1988. Pro/ENGINEER was the first parametric feature-based solid modeling software and allowed engineers to more easily design components and complete systems. Today, several 3D CAD programs are available. The 2D CAD software is still widely used in some industries, such as architecture.

In addition to these primary evolutions, the overall system performance and inherent functionality of CAD software have increased as general computer technology has improved. Current CAD software can create mechanism animations and realistic surfacing, among other features.

The cost of individual seats of CAD software has also decreased significantly. In the 1980s and 1990s, CAD software licenses were often so expensive that only larger companies could afford to invest in the seats and the continual upgrades. Software developers have created “light” versions of many of their products that are more affordable to smaller businesses and engineers who don’t need the full functionality of the complete versions or do not have the budget to purchase the full version.

The CAD software is one of the tools that is used by just about all engineers across all disciplines of the engineering profession

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Popular Computer Aided Design Software: The Top CAD Programs Used by Engineers

Top CAD design software

Engineers use computer-aided design (CAD) software to perform many of their design and optimization tasks. A variety of CAD packages are available with different functions and target users.

2D CAD Packages

The original CAD software packages developed as analogs to the physical draftsman’s table. The two packages that dominate this market include:

  • AutoCAD – Autodesk’s AutoCAD is the grandfather of all commercial CAD packages. First released in 1982, AutoCAD is the premier 2D digital drafting package, although 3D modeling functionality was added with the AutoCAD 2007 release. The latest version of AutoCAD includes parametric modeling capabilities as well as mesh modeling. The file format for drawings used by AutoCAD, DWG, has become the standard file format for CAD system interoperability. While pure 3D packages are gaining market share in many areas, AutoCAD is still the preferred package for architects.
  • TurboCAD – TurboCAD, currently owned by IMSI/Design LLC, was originally created as a low-cost competitor to AutoCAD when released in the US in 1986 with a price of $99. TurboCAD was popular with computer resellers and educational channels. TurboCAD added 3D functionality in 1995. TurboCAD supports a variety of third-party plugins for specialized functionality.

Several other smaller packages are still available, and many others have been discontinued over the years as AutoCAD has thrived.

3D CAD Packages

The development of 3D CAD systems has revolutionized engineering design. The top 3D CAD packages include:

  • Autodesk Inventor – Autodesk entered the 3D modeling system market in 1999 with its Inventor package. Inventor is a 3D parametric history-based modeling program, whose functionality Autodesk calls “virtual prototyping”. Inventor includes specialized environments, such as sheet metal, frame generation, tube and pipe, and cable and harness.
  • Pro/ENGINEER – PTC’s Pro/ENGINEER was the first 3D parametric modeling solution available to the engineering market, released in 1987. Pro/ENGINEER is an integrated application, including CAD, computer-aided manufacturing (CAM), and computer-aided engineering (CAE) functions. A wide range of modules is available for a different design, manufacturing, and industry needs. Pro/ENGINEER supports the design of individual components and complete complex systems of components.
  • Solid Edge – Solid Edge, currently owned by Siemens PLM Solutions, was originally developed in 1996 by Intergraph. Solid Edge competes for market share with Pro/ENGINEER, Solidworks, and Autodesk Inventor. The system can integrate with Sharepoint to provide product lifecycle management (PLM).
  • Solidworks – Solidworks, now owned by Dassault Systemes, was first released in 1995 as a low-cost competitor to PTC’s Pro/ENGINEER package. Solidworks employs a top-down engineering approach, allowing users to start with a 2D or 3D sketch and refine the design, as an engineer would do on paper. Solidworks supports a variety of toolboxes and modules for a variety of specialized functions, such as simulation and product validation, as well as product data management (PDM).

Other commercial and company proprietary packages do exist, but these software systems dominate the 2D and 3D CAD markets.

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Photoshop Elements Image Size and Resolution: How Adobe Uses Dimension Pixels and DPI in Print and Screen Photos

Photoshop elements

When using functionally-rich image editing software such as Adobe Photoshop Elements, it is important to understand the principles of resolution (dpi) and size (dimension) as well as how these relate to print, web and screen images. This will help avoid confusion when, for example, images are printed too small or huge photographs are displayed on the screen.

What is the DPI of an Image?

DPI is a fundamental concept in dealing with images both online and in print. DPI stands for Dots Per Inch and is an approximate measure of the resolution of an image. The key ideas can be explained simply as follows:

  • Imagine a square one inch long. The dpi measurement would be the number of dots that fit along the edge of the square. It is possible to draw the edge of the square with many or few dots and still recognize the edge.
  • Imagine an image printed on stretchy material. The actual image will stay the same, whether the material is stretched or not, but the density or resolution of the image will change. If the image was printed on loose material and then the material was stretched a long, long way, then the quality (resolution) of the image would decrease as it would be harder to see the details. On the other hand, if an image is printed onto a stretched-out piece of material and then the material is released, the resolution of the image would be higher and quality would look the same or improved.
  • On a computer screen, everything is displayed at 72 dpi – that means that for every inch on the screen there are 72 dots making up the image.
  • High-quality printing typically takes place at 300 dpi. So for every inch, 300 dots are printed.

A photograph, which may be scanned into a computer at 300 dpi, ready for printing will display on a 72 dpi screen much larger than the real-life photograph. Similarly, when creating an image in Photoshop Elements at 72 dpi, it may display at an expected size on the screen, but when printed at 300 dpi it will look much smaller on paper. This is due to a resolution.

Dimension (Length) Measured in Inches, cm, mm and Pixels

An image can have fixed dimensions such as length, width or height. For example, 10cm, 100mm or 8 inches.

Photoshop Elements allows all images to be manipulated based on both dimension (lengths such as mm, cm or pixels) and resolution (dpi).

The dpi dot is often referred to as the pixel and images can also be set to a length of a certain number of pixels. 

Changing Image Size

A common requirement is to change the size of an image and in Photoshop Elements this can happen in a number of ways.

An understanding of the resolution and dimension of an image are important when completing many tasks in Photoshop Elements. A typical task could be taking a high quality photograph and then displaying it on a web page. The photograph may have been taken on a digital camera and stored on the computer at 300 dpi (or more) and be too large for a web page. All screens display at 72 dpi so there is no point having a huge, high quality file on the web page. The resolution needs to be set to 72 dpi and the picture dimensions need to be reduced to fit the design of the web page.

In Photoshop Elements 6.0, once the file has been opened and the photograph is displayed, the following selections should be made:

  • From the menu, ‘Image’
  • ‘Resize’
  • ‘Image size’

The resolution should then be set to 72 pixels/inch – the dimension of the image (in pixels) will be automatically updated to keep the dimension the same. The dimensions can be changed if required, either by changing the number of pixels or by changing the length in cm, mm, etc.

If a change to a photograph has resulted in the image on screen looking much larger or much smaller than expected, it is probably due to the incorrect resolution being used.

An understanding of image size in terms of resolution and dimension will help users to exploit Adobe Photoshop Elements functionality.

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