Panoramas From a Train
Panoramas From a Train
I got the train home on a slightly different route the other day. The train was mostly empty so I was able to get a good window seat. The different route was a slower path through some of the largest train yards and junctions in North West London so I though it might be interesting to experiment with an idea which had been in my head for a while waiting for the right moment.
If you've ever used panorama mode on your phone you'll know the concept of standing in a location while slowly scanning a scene my sweeping your phone in an arc around your static location to capture a wider than usual view. Panoramic images certainly have a lot of impact whether in the city or out in a spectacular landscape.
I wanted to try changing the "body rotation" concept by pressing the phone against the window of the train and using the linear motion of the train to scan the passing environment. Like a giant flat bed scanner. And so on the half hour journey between Shepards Bush and Harrow & Wealdstone I took several panoramas (or perhaps they should be called scanoramas!!)
So how did they work out and what were the quirks. Well they worked very well but there were a couple of issues. First is to make sure the scanorama is going to scan in the correct direction. On the iPhone the direction can be changed by tapping on the big white arrow which shows on the screen when you start a new panorama. The second issue was speed. The camera can only figure out what is going on if the movement isn't too fast. By that I don't necessarily mean how fast the train was going. It was more about how fast the objects in the scene were passing by. If the train was quick then bushes and overhead gantries got a bit corrupted in the final images. Things in the distance worked better at higher speeds. At slower speeds closer objects worked great.
Another issue was passing through short tunnels and bridges. The contrast between a sunny scene and the shadow under a bridge was too great for the camera to handle.
Lastly, and something which surprised me a bit was that things in the distance came out a bit odd at times. Mostly clouds in the scanoramas got quite smeared. I think it might be because of the way the camera builds the image. I think it must add a vertical column of pixels from somewhere just back from the leading edge of the camera sensor to the panorama as it builds it up to the final image. The cloud is so far in the distance that it doesn't shift very much in relation to objects in the foreground. Parallax comes into play. The reason I think the Pano mode on the iPhone adds a column of pixels from somewhere back from the leading edge of the sensor is that at either end of the cloud streaks is an area of normal looking clouds which are kind of book ended on to the ends of the Pano.
So what did I learn. Well it was great fun to try something new and figure out what was happening. For a first attempt the results are not bad at all and in fact I quite like the glitches and errors caused by the "issues". I'll definitely be trying again next time an opportunity presents itself.
Not going too fast and the trees came out quite well but look at those streaky clouds.
Bit of a glitch on the bridge with this one but I love how a train passing in the other direction got compressed into a few meters.
A slower train leaving Wembley Central allowed for a much smoother image even with close up scenery
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