offbeat idea for video..

[Fred588]

This is a reply to Robert's most recent comment below. I am posting it without the quote to avoid making things too complex to follow.

To make a scene in which the model can be seen covered in mud and then not as the mud is washed off, at least by the green screen or keying effect would be quite difficult. First, the model would have to be covered in something green that woul not come off between applying the mud and having it washed off. Since the green does have to be washed off eventually that is a fairly tall order. Possibly a full body layer of green pigmented latex could be employed. Second, the green screen technique requires that whatever is green be evenly-enough illuminated that the keying filter software can distinguish between the colors to be removed and those to be left. The software does not work the way human vision does so this is n ot a simple task. With water flying around this would be complicated further. Third, when the green on th model is rendered transparent, whatever video layer is behin d it will show through. If what shows through does not blend in with its surroundings then there will be an "edge" outlining the model where the pixel pattern changes. This might be accepted as a "partially" invisible person but it would be visible as such. There is a technique by which a separately-filmed shot of the same scene but without the model is used as the background layer but this would require either a completely static camera throughout the clip or use of some very expensive tracking gear so that all camera movement in the two layers is identical frame by frame.

This is not a project I would undertake except as an experimental custom assignment, as I am dubious of its success given what is practical for use.

[Robert]

This is a reply to Robert's most recent comment below. I am posting it without the quote to avoid making things too complex to follow.

To make a scene in which the model can be seen covered in mud and then not as the mud is washed off, at least by the green screen or keying effect would be quite difficult. First, the model would have to be covered in something green that woul not come off between applying the mud and having it washed off. Since the green does have to be washed off eventually that is a fairly tall order. Possibly a full body layer of green pigmented latex could be employed. Second, the green screen technique requires that whatever is green be evenly-enough illuminated that the keying filter software can distinguish between the colors to be removed and those to be left. The software does not work the way human vision does so this is n ot a simple task. With water flying around this would be complicated further. Third, when the green on th model is rendered transparent, whatever video layer is behin d it will show through. If what shows through does not blend in with its surroundings then there will be an "edge" outlining the model where the pixel pattern changes. This might be accepted as a "partially" invisible person but it would be visible as such. There is a technique by which a separately-filmed shot of the same scene but without the model is used as the background layer but this would require either a completely static camera throughout the clip or use of some very expensive tracking gear so that all camera movement in the two layers is identical frame by frame.

This is not a project I would undertake except as an experimental custom assignment, as I am dubious of its success given what is practical for use.

Well, at the risk of repeating myself... I did say it would not be easy, specially using the programs and camera's that most producers here currently use. It would take research, and the time and place to do it.