system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can 20 year old movies like Jurassic Park and Terminator 2 have really convincing special effects, whilst the CGI in newer films looks completely unrealistic?
gpt
Well to be honest there are some movies that are just one big special effect ( Gravity or Life of Pi ) that look extremely realistic.

CGI is basically an art form you can think about it like painting a picture. If you rush an artist and only pay him little money your picture will look stupid even with the newest tools like Photoshop.

With CGI this problem is even bigger you need to perfectly fit to the movie scene (shadows, color, size, clipping, ...). And that isn't even enough to make effects look right you need to know about physics and construction to make your imaginary effects look like they could be real.

If you want a realistic dinosaur your artist needs to learn the anatomy of a dinosaur, he needs to learn how dinosaurs move and he needs to make very detailed model (every pump in the skin has to be there to make it look real). And you usually need additional footage from the movie scene to make any reflections perfect. So basically you get what you pay for.