Re-rendering Toy Story with a global illumination lighting model would make a huge difference though, even if the geometry and textures remain the same.
It would look horrible, because the lighting was done assuming no global illumination.
Besides destroying artistic intent, the no-longer-missing indirect lighting effects would double up with all the "cheats" and clever techniques the artists had placed to make up for them.
Obviously all shader code and lighting would have to be redesigned. I wasn't trying to suggest that they could just multiply a GI render pass on top of the old shader output, or something like that.
It's not a matter of code (though that, too, would be an enormous job). It would clash with what the artists have done.
Here's a random image from TS1: [1]
Look at Buzz's butt-- he has some yellowish up-lighting. That's because an artist placed a yellow light underneath him to fake the indirect light from the bedspread. If you turned on GI, the bedspread would cast its own yellow light, and it would look wrong because now his butt is glowing.
Not to mention that ambient occlusion would likely darken lots of things that weren't supposed to be dark in the original composition. Really, it would look totally broken and destroy the artistry.
As I said, lighting would have to be redesigned. We're not disagreeing.
I don't think it's something that Disney should ever do. I was just replying to the person who suggested that limitations in geometry and bitmap assets mean there's nothing that could be done to upgrade the look.
Ops point was that old movies could just be rerendered and quality would improve dramatically, and i disagreed. Of course, if you put in a lot of work and rework the entire lighting model and other things, you can improve quality a lot, but that wasn't the point.
