Just a simple straight forward question.

Obviously, with the transition from SD to HD, we are jumping up 3 times in resolution terms from 480 to 1080.  What implications will this have for films with special effects?  Do some films need to re-render the CGI effects for HD or are the effects simply rendered at such a high resolution at source, there is no problem with the transition.

I was thinking about the potential release of Star Wars Phantom Menace etc.  These films were done some time ago and although the visuals were done by ILM and were probably done at superbly high resolutions, I do recall that extra work was done for their DVD release.  And obviously the consumer wants the best quality visuals, especially for these films, and seein as texture quality as well as model build quality is more noticeable at a much higher resolution than SD.  Will there be some extra work involved.

Maybe I picked the wrong example seeing as the Star Wars films have always had cutting edge visuals, but what about a slightly older film that uses CGI for it's effects....will this be an issue?

See:
35mm vs HD


How many pixels in 35mm

In terms of films shot on 35mm or 16mm cameras no!

SD footage or features would probably just be upscaled, no extra work needed.

Its worth noting that filmmakers/directors shoot films on different mediums to get different image results to suit the film.

Blair Witch remastered or remade into HD wouldn't have the same effect.

In regards to CGI rendering, this would typically be done to match the original source material. An exception might be films getting a straight to DVD release.

In the early days of CGI their was an air of caution in how to use it properly. Famously James Cameron filmed The Abyss in NON-ANAMORPHIC widescreen so he could match the CGI elements without having to un-squeeze the image.