Chroma Key vs masking

[LucaM]

I would like to change the background in a simple scene (a few seconds long, no movement of the actor, a diffuse neutral soft light to match the one in the final background) . I would like the camera to turn 180 degrees around the actor to show what he Is looking at without (at least visible) cuts (i don’t remember how this shot Is called, sorry: semi arc shot?)how would you suggest go do It? A green screen or rotoscoping and masking? The first option seems simpler to me but i think it would require more planning in pre production in terms of set and lights planning, the second is more immediate but masking and rotoscoping require a lot of work in post and i’d avoid it if possible. Any advice? Thanks!

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[dmullenasc]

Either way you are designing a shot that requires the creation of a traveling matte — a chroma key / color difference key (using a green or blue screen usually) is the simplest post method compared to rotoscoping. Now if the actor became a near silhouette against the new background, you can sometimes get away with a white screen and pulling a luminance key rather than a chroma key, but even that may take some clean-up work.

Generally it’s better to take the time in shooting to get something that works well for post than to hand footage to post that needs a lot of work, especially if you don’t know how good your vfx people are or what sort of budget/time constraints they will be under.

Or put the actor in front of a big LED screen where the screen image itself rotates from the old to the new and spin the actor on a platform…

[LucaM]

Thanks David, you’re always very kind! Your knowledge and experience are always precious!

I’m going for the green screen, i think It will allow me more freedom for the camera movement and It seems the simplest solution. To achieve the 180 degrees movement I still have to figure If It’s simpler to work with a green screen with maybe 3 sides around the actor or edit two shots and “hide” the cut, but the rotating platform could really be a great idea!

[Author]

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