Line scan sensors are basically just scanners, heck people make em out of scanners .

Usually the issue is they need rather still subjects, but in this case rather than the sensor doing a scanning sweep they're just capturing the subject as it moves by, keeping the background pixels static.

Thanks, I added a section called "Principle of operation" to explain how it works.

You use a single vertical line of sensors and resample "continuously". When doing this with film, the aperture is a vertical slit and you continuously advance the film during the exposure.

For "finish line" cameras, the slit is located at the finish line and you start pulling film when the horses approach. Since the exposure is continuous, you never miss the exact moment of the finish.

Imagine a camera that only takes pictures one pixel wide. Now make it take a picture, for example, 60 times a second and append every pixel-wide image together in order. This is what's happening here, it's a bunch of one pixel wide images ordered by time. The background stays still as it's always the same area captured by that one pixel, resulting in the lines, but moving objects end up looking correct as they're spread out over time.

At first, I thought this explanation would make sense, but then I read back what I just wrote and I'm not sure it really does. Sorry about that.

The video [https://www.magyaradam.com/wp/?page_id=806] blew my mind. I can only image he reconstructed the video by first reconstructing one frame's worth of slits — then shifting them over by one column and adding the next slit data.