Okay I was stumped about how this works because it's not explained, as far as I can tell. But I guess the sensor array has its long axis perpendicular to the direction the train is traveling.
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You can also get close in software. Record some video while walking past a row of shops. Use ffmpeg to explode the video into individual frames. Extract column 0 from every frame, and combine them into a single image, appending each extracted column to the right-hand-side of your output image. You'll end up with something far less accurate than the images in this post, but still fun. Also interesting to try scenes from movies. This technique maps time onto space in interesting ways.