Mind blown - how is this done?

[PistolPete]

http://www.bbc.co.uk/news/uk-politics-17920260

I understand the principles of chroma keying, but how do they manage to move the camera around without any obvious signs of tracking markers and how do they get the graphics to appear in front of the presenter - is that a simple overlay? Again, how do they track it??

 

[PistolPete]

Ah, never thought of that.

 

[PistolPete]

When they first remove the graphics and show the green floor, you can see a rectangle painted across the map of the UK. He knows that when he stands behind that box that the graphic overlay is in front of him and that when he stands in front of it, the overlay is behind him. Simply a case of positioning the overlay properly on screen.

Clever use of technology really.

So you do..... however the tracking bit is still very clever.