Capturing side view whilst on a train


#1

I’ll be taking a long train journey from middle of England to north of Scotland next month (min 10 hr train journey) and was wondering if there’s any value in capturing images from the side window of the train. What information can Mapillary get out of such images to enrich the base maps?

As a test, I mounted the phone to a side window of my car and found that almost every image captured was blurred. Trying to phone to point 45 deg forward was difficult due to the size of the phone and the mount (I got sent from Mapillary).

So, any suggestions welcome.

Thanks.


#2

use webcamera + GPStracker

sample 45 degree


#3

Some phones just don’t have the shutter rate to handle fast side movement. Action cameras would be better. That said, with rolling shutter (on either phone or action camera), you will notice either jittery lines from vibration or simply diagonal stretching (see https://www.mapillary.com/app/?focus=photo&lat=41.943499990736086&lng=12.510251160742882&z=17&pKey=KHL-n1q_tJ_J_QnarJojxQ). I still think it can be nice to have those photos, though.


#4

A few thoughts

  • If you have a choice pick the down sun side of the train. More light, higher shutter speed
  • Glue a temporary angled mirror in front of the lens for the 45deg situation and preprocess images. (internal glass reflection will be a problem though)
  • Anchor the phone more firmly to the window (in case blur is from shake not pan)
  • Widest angle view (no telephoto)
  • Test at different resolutions (there may be a shutter speed difference)
  • If you have raster based slant something like imagemagick may be able to correct. Most of the train journey might be at a steady speed making that easy. (GPS speed could be used though!
  • Clean the window

Cheers


#5

Thanks everyone for your suggestions.

The devices I have in my possession are:
iPhone 6
iPhone 6+
iPhone X
Nokia 8
Nexus 4
Yi Action Cam

Not sure what’s the fastest shutter speed or the type of shutter (rolling or otherwise) on these devices, but I’ll have a go at trying out a few of the suggestions.


#6

I recorded on the way back to Ohio from California. I found that when it got dark, with no head lights, it was not worth recording.
I mounted the phone at about a 45 degree angle pointing back the way the train had come.
The only blurry shots were when the train tracks passed close to buildings and Bridges.
I’m not sure how much value there is in this recording.


#7

Thanks @JBTheMilker. Yes, that was my question too to Mapillary developers. Is there any value in recording side views of a train journey.


#8

The photo I linked to was with a Yi Action camera. I also have a Nexus 4, and the camera is pretty lousy. I would guess that any of the other phones would probably be fine, because I know some of the modern ones have pretty good cameras, but I don’t know how they would compare to the Yi.


#9

ive been wondering the same thing as well. i had a quick look around the map (in ireland) and found these sequences. the image quality is not great though and they dont last long enough to tell whether you would capture that many interesting things



the last time i was on a train i held my phone up for a bit as well to see what it was like and photos were similar enough to the above sequences. slightly blurry and not much to look at apart from fields and trees but you might have better luck if you are going through a lot of towns and cities

ive got a gopro since though s next time ill see whether that does any better for shutter speed

having the camera in the drivers cabin would be ideal… but then you worry about haggling with the driver to let you leave your phone in there or whether you want to trust the driver not to be looking through your txt’s :smiley:


#10

Thanks for the sample images. Yeah, they don’t look very interesting. Of course, it would be ideal to be able to mount the camera in the driver’s cabin, but not sure if they’d be happy for me to do that.

My wife and I will be travelling to Fort William in Scotland from West Midlands and from Fort Williams we’ll be travelling on a special scenic rail service (that runs only twice a year) going over the famous Glennfinnan viaduct (made famous from Harry Potter films https://bit.ly/2Wtkkwc) and other Scottish Highlands.

I’ll ask the train company if they wouldn’t mind sticking my phone in the cabin of the driver.


#11

Hi

I tried in canada, and it was not worth doing so (toronto-Montreal).
While in europe sometimes it was worth the try, it works mostly with open windows and 45 alike degree ahead or backwards.
If possible, I go to the end of the train and use the window showing back and take that view (e.g. ennstal in austria). Thats quite fine, just need a mobile holder :slight_smile:

echelon


#12

As you’ve seen, it will depend on the camera and the lighting. It sounds like you’re looking for humans. For me, I’m not so worried about that as just raw data that could be useful for generating data.

Anyway, here’s one from The Skyway in Jacksonville. On a sunny day it works great.


#13

What would likely be of interest, both to Mapillary and to OpenStreetMap contributors, are shots of roads and parts of towns and villages which can otherwise not be seen from the tracks : your photos may well tie various elements in other photos together.


#14

thats a great idea!