What is a TD?

A TD is a Technical Director. But I've always wondered why they're called Technical Directors. What do they direct? How did this term come about? Depending on which company you are at, sometimes they're called Lighters.

Even at some other companies, TDs often do the compositing as well! So what is a TD? I asked some TDs, and here are their responses.

Wikipedia states:

The technical director is usually the senior technical person within a single business unit of a company. This person usually possesses the highest level of competence in a specific technical field and may be recognized as an expert in that industry. The technical director provides technical direction on business decisions and in the execution of specific projects. He or she may be assigned to a single project, or may oversee a number of projects with related technologies. This position is often similar to that of chief scientist or chief engineer, but perhaps more involved in business decisions. Technical directors and chief scientists often report to the chief technology officer of the company.

Howard writes:

The term comes from ancient Mayan I think. The TD, in Mayan culture, is the most revered of their gods. Worshipped for bringing light to the world. Often in battle with his nemesis "comper, the trickster".

Alan says:

The TD title is on it's way out. It doesn't in any way describe the role of people who have the title. If you look at recent credit lists, the people we call TDs here are actually credited as lighters.

Ultimately, the most accurate description of a TD is here, http://www.3drender.com/jobs/TD.htm, written by Jeremy Birn.

The work that many TD's do in lighting and rendering is similar to the work of the "Director of Photography" (or DP) in live-action film production. Otherwise, the name TD can be a bit misleading, and some studios don't even use the term. At some companies, the person lighting a shot would be called a Lighting Animator or simply a Lighter, instead of a Lighting TD. People rigging characters are sometimes called a Rigger, Puppeteer, Physiquer, Technical Animator, or other titles instead of Character TD. Because of this, some companies will never list a help-wanted ad for TD's. A TD by any other name is still a TD, though, and they still need to hire people with similar skills for any computer graphics production.