@Rich-O-Brien Thanks Rich. The first one I used D5 Render's AI enhancer. I did notice the other day that it completely warbled th chain so I have to look out for those results. The rest is just downscaling from 4K to a 2K image and sharpening in my ancient Photoshop. I'm also trying new lighting effect in D5. It's a lot of dials, bells and whistles. The D5 decals are easy to create by using one of their decals and just dragging and dropping any new textures from Explorer from say Quixel Bridge. My graphics card is by now an old Asus ROG RTX 3060. The 4080 is still too expensive.
I managed to get the model down to 26.5 MB by create a D5 model of the railroad tracks and consolidating SU components. If an item is symmetrical I just split it in half and crate a component out of one half. The emergency light for example is made up of 4 components. The trucks are split in two where symmetrical like the wheels, tubing, frame and brakes.
