I've got as much details as you unfortunately. Official site doesn't provide any info beyond what's in the trailer description.
This movie contains a heavy amount of CGI so they most likely rerendered the whole thing from scratch, assuming they still have the source files for that stuff.
Edit: I looked around a little bit and while I didn't find anything official I saw some suggestions this might just be an anniversary screening of the Japanese release from few years ago. Let's hope we'll get some more info on that.
...dreamworks published the DVD without english subtitles, instead providing only descriptive closed captions...
...it's an amazing film but the closed captions were a terribly compromised viewing experience, poor enough to tank DVD sales and put the film into distribution purgatory under the terms of dreamworks' original contract...