Using 'Green Screen' whilst filming

We decided we wanted to use the 'Green screening' to shoot a few of our shots. This is because we wanted a shot of our spy girl fighting someone on the top of a skyscraper building or something along those lines. We also needed a guy on computer in a high class office, and we needed pictures of our main protagonist as if she is stood on top of a city.The only way to achieve these things was to use 'Green Screen'.
'Green Screening' is where you electronically 'cut out' a subject shot against a coloured screen. Once the subject has been removed from the background colour, you can then place it on an upper track, which then allows you to place it on a different background. This creates good visual effects.
We have choose the backgrounds based on our brand image as we are trying to carry out the same brand image the whole way through.

These are our backgrounds below.

These are the backgrounds we decided to use. The picture of the lights at night time is a primary image which we took of Blackburn at the top of a hill. The images of the office and the bricks were found on google images as we thought these fit in well with our film and were from the right perspective. We got them from google as it would have been very difficult to get these as primary images. We thought the original image of the construction site looked a bit too bright and happy for our teaser trailer so we made it look more bleak and gloomy by using the software Photoshop.

These are some images which we decided not to use: