AutoCAD LT 2005: The Defining Difference

AutoCAD LT is one of the better deals around — a shining example of the old 80/20 rule: roughly 80 percent of the capabilities of AutoCAD for roughly 20 percent of the money. Like AutoCAD, AutoCAD LT runs on mainstream Windows computers and doesn't require any additional hardware devices. With AutoCAD LT, you can be a "player" in the world of AutoCAD, the world's leading CAD program, for a comparatively low starting cost.

AutoCAD LT is a close cousin to AutoCAD. Autodesk, the company that makes the two programs, created AutoCAD LT by starting with the AutoCAD program, taking out a few features to make the program a little simpler to use (and to justify a lower price), adding a couple of features to enhance ease of use compared to full AutoCAD, and then testing the result.

AutoCAD LT 2005 is almost identical to AutoCAD 2005 in the way it looks and works. The opening screen and menus of the two programs are nearly indistinguishable, with LT missing a small number of the commands found in the AutoCAD 2005 menus.

In fact, the major difference between the programs has nothing to do with the programs themselves. The major difference is that AutoCAD LT lacks support for several programming languages that software developers and even some advanced users employ to create utilities and industry-specific applications for AutoCAD. AutoCAD supports add-ons written in Microsoft's Visual Basic for Applications (VBA), in a specialized AutoCAD programming language called AutoLISP, and in a specialized version of the C programming language called the AutoCAD Runtime Extension (ARX).

Software developers, including Autodesk's own programmers, use AutoCAD's support for these programming languages to develop add-on programs that work with AutoCAD. For example, AutoCAD includes a set of handy utility commands called the Express Tools, and Autodesk used AutoLISP and other AutoCAD programming languages to create them. Other software developers create specialized applications for architectural drafting or other industry-specific needs.

AutoCAD LT doesn't support any of these programming languages, so most of the utilities and applications developed for AutoCAD don't work with LT. AutoCAD LT does include the same menu and script customization features that AutoCAD has. As a result, a few very simple AutoCAD add-ons do work with LT. For example, you can purchase or download block libraries — collections of drafting symbols — that work with LT.

AutoCAD LT also has only limited 3D support. You can view and edit 3D objects in AutoCAD LT, so you can work with drawings created in AutoCAD that contain 3D objects. You also can extrude a 2D object, which gives you a limited ability to create 3D models. (CAD people call this ability "2-1/2 D" because it's limited to giving 2D objects depth in one direction.) However, you cannot create 3D surfaces or solids.

The lack of 3D object creation in LT is not as big of a limitation for many people as you may think. Most companies use CAD to create 2D drawings most of the time. Although 3D modeling can be effective for some kinds of work, it requires a lot more skill and sophistication on the part of the user. It also begs for more computing power. A reasonably current, no-frills computer that runs AutoCAD LT quite respectably is brought to its knees if you try to do real 3D modeling and rendering with AutoCAD on it.

Although you may hear claims that AutoCAD LT is easier to master and use than AutoCAD, the truth is that they're about equally difficult (or easy, depending on your nerd IQ). The LT learning curve doesn't differ significantly from that of AutoCAD. AutoCAD was originally designed for maximum power and then modified somewhat to improve ease of use. AutoCAD LT shares this same heritage. The most notable example of this penchant for power over ease of use is the command line (that text area lurking at the bottom of the AutoCAD LT screen).

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