Step 4: A) Stopmotion
Therefore, you need:
A camera - Or even an iPhone. There are some stopmotion apps where you have the movie right on your device already.
A tripod - The heavier, the better. A infrared trigger for the camera guarantees a still image.
A background - That doesn’t move. Sky does move. And natural light changes quickly.
A video editing software - Or Photoshop.
The camera has to make all images with the same settings, so find the optimal settings and turn white balance and auto focus off.
Then mark the spots where the objects are on the underground, you can either animate only one object or a few at once. They just can’t do exactly the same motion then, the closest would be one animation phase of difference.
Then, don’t ever touch the camera again and make your shots. After each shot, replace the current object with the next one.
When you are done, make a quick preview with scrolling through the images on your camera. Sometimes there are little movements in the background that you could not notice.
When everything is fine, transfer them onto your PC and place them in sequence into your video editing software, every picture showing up for one frame.
Photoshop has an animation feature, which allows you to animate the frames when you have them in different layers. The advantage would be that you can equate tiny movements of the camera through moving the layers a bit with the cursor keys. When you set the blending mode to Difference, you have a great overview of the shift. This tutorial shows you how to generate a GIF out of the frames: http://creativetechs.com/tipsblog/build-animated-gifs-in-photoshop/