NASA’s Curiosity Rover snapped photographs at 5 frames per second as it descended onto the face of Mars a few weeks ago. The footage that results when the images are combined into a 15 frame per second HD video is pretty amazing, but apparently not amazing enough for a YouTube user named hahahaspam. He spent four straight days taking the 5 fps footage and interpolating it to 25 frames per second. This means that instead of a video showing the choppy landing at 3 times the actual speed, his video shows the landing smoothly and in real time!
Video interpolation, also called “inbetweening” or “tweening”, involves creating the intermediate frames in between the real frames in order to give the illusion of a faster frame rate and smoother footage. In the case of this rover landing footage, hahahaspam had to create 4 “transition” photos for each of the original photographs.
Here’s a comparison between the original video and the new interpolated version:
Here’s his explanation on how he did it, posted over on Reddit:
I downloaded the 1648x1200px pictures from here and imported them into After Effects as an image sequence. Then I stretched the image sequence to run at 25 fps which resulted in a legit frame being copied 4 times until the next real frame came. At this point, I went to the original image sequence and started oding manual motion tracking, watching a crater here or there. I made sure I always had at least two data points at any given time so that I could reposition and rotate for fluid motion.
Well, this wasn’t quite enough because I needed the difference in movement between frames, not motion overall, so I coded for position and rotation with After Effect Expressions [...]
This gave me a pretty good approximation for the main duration of the descent. Near the end I had to start accounting for changes in scale, and I went in a manually had fun with the heat shield for the first couple seconds of its descent. That’s why it looks extra smooth for the first bit.
Interpolation is how programs like Twixtor can take ordinary camera footage and turn it into what appears to be slow motion footage captured with a high speed camera.
Last week we shared an experiment Gizmodo did in which they captured 5K footage by stringing together 14fps still photos shot using a Canon 1D X DSLR. Someone should try taking that 14fps footage and boosting it past the flicker fusion threshold using interpolation…