How did they remaster this remake?

[Kadu]

REmake released originally to the Gamecube, and in 2014 when Capcom released this remaster, i was shocked to how better it looks, but i still have many questions.
The pre-rendered backgrounds still look very compressed and low res, so many would think that they didn't have the original 3D files used to render the backgrounds and they couldn't render it again, and it resulted in Capcom just using the same low res backgrounds used in the gamecube version.
BUT, when i used an emulator to see how the old backgrounds looked in 1080p, i was surprised to see that they look even more compressed and low res. The new backgrounds have many small details that weren't visible in the original, everything is much sharper and even the pre-rendered cutscenes look better in the PC remaster.
Now here is my question:
If they didn't render the BC again, how did they made them look so much better?
And if they actually had the original 3D files and they've rendered them again, why didn't they render in high quality?

None of that makes sense to me, and i couldn't find any info on the internet.
I would love answers and chatting with people who know about this more than me.

[James.Havoc]

They didn't have the 3D files anymore. In some cases they had rebuild the entire room build it in the same RE0 does it. (as a movie file instead of static picture). The crypt where you have to put the four masks in the right place is one of those rooms
Its either that they run all the existing BG through multiple filters to polish them up, or they had access to the raw, uncompressed BGs from 2002, which looked better then the BGs from the Gamecube but are still done in 2002, where the common resolution was 1024x768 to 1280x1024.

[Kadu]

Holy s h i t thanks, that makes a lot of sense, rebuilding *some* of the envoriments makes sense considering the game actually have the modeled envoriments because it uses a lower poly version of them to serve as hitboxes as well as casting lights and shadows. That would explain why some textures seem a bit different in this remaster.
And the raw file theory is the one i believe to be the method they've most used, because if they had actually re-rendered ALL envoriments, they would use a higher res to the BG.
Idk if you've watched this, but i love this video: https://www.youtube.com/watch?v=j0L5Y_T502U

[James.Havoc]

No, that video is new to me. Kinda interesting...and a shame how much details they "hide" in darkness.

[Kadu]

I wonder: if the envoriments are actually modeled and rendered in real time, couldn't they just texture them and make it completely real time? They are already being rendered in real time anyway.
Actually, i was thinking about trying to rip some envoriments and add textures to them in Blender.
I think that if i did this, it would be the very first time we would be able to see in full 3D how the mansion actually looks in this game, but i couldn't do it because NinjaRipper isn't able to boot steam games, and i don't know how am i going to use it to extract the models.
But if i get it working, i'll definetivelly add textures and effects to at least one room (probably the dinning hall) and then render it in cycles with ray tracing.