I use decimation, but non-destructively (as in 20-30% reduction). Leaving some pieces still upwards in the 1 million poly mark. Without render instancing, the model is about 40 million polys, with a single toe alone taking up 800k. This is a huge problem in production, but seeing as I have the ram and processing power to handle it, I work with models as I see fit.
I was beta testing the new zbrush features weeks before they came out, but sadly I wouldn't have been able to use them without causing problems.
I have no knowledge of 3D whatsoever, but that looks amazingly impressive! Just quick question; is it just me or are certain parts of the gattling guns (on either sides of the mech) missing? E.g.: the 2e picture on top - I can't seem to see the end of the gattling gun on the left, and the first picture down bellow seems to be missing half of the gattling gun on the right...Is that just a rendering glitch, am I misinterpreting things, or am I hallucinating? Either way, marvelous job!
It's the subtle IOR in the glass, giving the illusion of light bending, the same as you see in a physical glass. It's sort of inaccurate to a degree (for this sort of thing), actually 0.6% off, but looked better than straight up transparency with no distortion for most angles. The guns however, remain where they should be.
I see not many the problems in the environment! It is also very detailed. I think perhaps the textures of materials in the back might use some improvement, but that is all from my eye. The lights too Could be very more real in another way, but that is another story for another render.