And no, it's not really possible to re-render the CGI at HD resolutions either. For one, the meshes and textures they created back then would never hold up under HD resolutions unmodified - instead making apparent low polygon counts, seams, UV mapping flaws and the like - and secondly, archiving for these digital assets is usually not done as diligently as with film negatives. The files are most likely largely lost to time, with companies involved having gone out of business, etc.
So they'd have to redo the CGI from scratch. As I've said a couple of times in this thread when this topic came up (it's always fun how these long threads keep circling the same issues as people move in and out of them), I'm happy they went with reusing the original model photography for TNG-R instead of going CGI, but the one advantage of doing the latter would have been ramping up a CGI pipeline they're eventually going to need for DS9 and Voyager. But then again I don't want them to train on TNG.
I'm fairly hopeful that in 5 years or so when they'd start remastering DS9 it will be cost-effective to do the CGI work though.
So they'd have to redo the CGI from scratch. As I've said a couple of times in this thread when this topic came up (it's always fun how these long threads keep circling the same issues as people move in and out of them), I'm happy they went with reusing the original model photography for TNG-R instead of going CGI, but the one advantage of doing the latter would have been ramping up a CGI pipeline they're eventually going to need for DS9 and Voyager. But then again I don't want them to train on TNG.
I'm fairly hopeful that in 5 years or so when they'd start remastering DS9 it will be cost-effective to do the CGI work though.