2 Replies Latest reply on Jul 28, 2010 10:57 PM by synapsemedia

    to walk on virtual ground or real ground?

    synapsemedia Level 1

      Hi everyone


      I am in the middle of planning a short film that will involve a lot of green screen work. Over the years I have watched a number of making ofs of big budget hollywood films some of them involving a lot of green screen work as well. I noticed that whenever a shot included peoples feet on the ground, they were never walking on a green screen. the ground, be it a desert, or road or whatever was always reproduced in the studio. why exactly is this? is it not possible to just have them walk on a green screen and replace the ground with whatever you want. on the other hand I suppose that if the ground were very bumpy and their would be mounds of dirt or grass covering parts of the actors feet that would be very difficult to recreate in post/compositing. Is my thinking correct here?


      My shortfilm in particular involves an actor walking on a tarred road (asphalt) could I get away with the actor walking on a green screen and then later on putting the road under him? or would there be undesirable artifacts/results that I am not aware of? Are smooth surfaces ok/doable on a green screen and its just bumpy sirfaces that need the "real thing"?


      Thanks in advance for any advice





        • 1. Re: to walk on virtual ground or real ground?
          Mylenium Most Valuable Participant

          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...



          • 2. Re: to walk on virtual ground or real ground?
            synapsemedia Level 1

            Hey Mylenium


            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?