We shot these blank scenes during filming so we could add the actress later in post. We couldn't get her to come as often during the filming dates, so we shot these empty and then when we had her come for other scenes we took photos of her matching the shot of the scenes and angles in mind.
Then on photoshop mask her out and add her to the footage we want. The I track motion the video and transfered the tracked frames to the girl so she moves with the camera and seem like she actually in the shot at the time, but the lighting was not perfect. To match the lighting with the video, had to use curves and match the colour and contrast so fits perfectly and not seem like it was jammed in the shot.
(RVJ sketch idea of photoshop the girl in another scene which she was not in at the time)
The video below is one of the cuts/video I used to the story to make it longer and makes sense. I needed a wide angle shot and a beautiful background location. We had shot some tests few weeks before and that day there was snow everywhere still havent cleared out. It looked awkward using these in the story as the rest of the scenes were in sunny day and this is in middle scene with snow. Still thought they were good scenes to use, We could not go to reshoot the scenes because we had to time left and we went over our timeline dates. It was in the week where we should be working in post. I just had to use the videos we had at the time.