The subtleties of the human walk... In short: walking on green/ blue screen always looks floaty. Walking on different grounds results in different foot rolling, pelvis rotation etc.. - walking in soft grass is different than walking in sand, even if the ground is level. Your muscles, bones and tendons will on an unconscious level compensate for compression, canting, direction etc. and that in turn ripples up to your spine, affecting whole body posture. Since we see people every day, we simply see this and if it doesn't fall within what we consider to be "normal" based on our experience, it looks wrong. The eternal bane of 3D character animators. And yes, of course som effects are hard to add later on. Depending on how fine or crude the pebbles in the tarmac are, shadow casting as well as the overall saturation would also look different and might be harder to match...
Thanks for the great feedback. yes, I see what you mean now. I think maybe what we will do is paint a fake tarred road in the studio. Considering that both the studio surface and a road surface are hard it should not be noticeable. I think we will be able to texture the paint to look more like asphalt. the walking/gait of the actor on the studio floor should be pretty much what the human eye would expect to see if he were walking on a real road.
What do you think?