Using Photoshop and Timelapse to make an empty version of Paris

Recently posted to Reddit, is Mathieu Stern’s intriguing short film project “Alone in Paris“.  While Mathieu promises that a Behind The Scenes video is coming in a week or so, it’s always fun to speculate how things like this can be created.

Some of the theories have already been shot down over on the Reddit post as the actual techniques used in this instance, but many of them are quite valid, and we’re going to have a quick look at a couple of them here.

When shooting stills of cities in an attempt to remove people from the scene, neutral density filters are often stacked quite highly in order to give exposures of maybe a minute or more (I’ve seen old film images shot this way that had exposures of several hours), allowing the moving people to have very minimal impact on the photograph while the static scene behind is exposed over time.

Unless you have an extraordinary amount of time on your hands, such a technique is difficult for timelapse, especially when you want to combine the timelapse with realtime footage.

There are no obvious signs throughout the video to suggest which method was used, but we can theorise.

One method that immediately springs to my mind is a process similar to this, but instead of using the images to composite multiple people into an area to make it look more populated, you composite empty spaces to create a deserted scene devoid of people.

While the actual process is slightly more involved when dealing with timelapse, the principle is the same.  It’s simply a case of layering and masking images from your sequence shot at different times, uncovering the entire scene between them, and then adding the moving parts of the image that you wish to keep (flowing rivers, moving clouds, etc.) back in.

You do need to be mindful of the moving light source in the sky (ie, the Sun), and on very heavily populated days, the time it takes to get enough shots to cover every part of your scene without people can make things very difficult, but it’s definitely a good way to go, especially if your cuts are relatively short.

Here’s a demonstration of how the above technique can be applied to timelapse footage using Photoshop and After Effects, with a tutorial video from a post we made in 2012 about the Empty America project.

Mathieu went the extra step beyond the video above in order to incorporate realtime video footage with his timelapse sequences, which adds yet one more layer of complexity to the project.

Exactly which techniques Mathieu used shall remain a mystery until he unleashes his behind the scenes tutorial on the world in a week or so, but I’m sure looking forward to finding out.

How would you tackle a problem like this?  Let us know in the comments.