[Talk-GB] Comparing current OSM tiles to historic ones

[George Honeywood]

Hi,

I've made something I think a few of you will find interesting. After 
seeing a couple of posts on the OSM subreddit about historical data, I 
figured it would be nice to be able to what changes have been recently 
(-ish) made in my area.

I followed a method fairly similar to the one in this post 
(https://hackmd.io/XfrY334rS7CV0tnPzx8Wvw), however after filtering the 
history file to the time I wanted I imported it into Postgres instead 
(using osm2psgl).

Once I everything in Postgres I first tried to use Mapnik and the nik4 
tool, which worked well enough but it was difficult to see the changes 
on a larger scale, as I had to manually create each image. It also 
wasn't great for comparing it to the current map, as I had to switch 
between images awkwardly.

Therefore I decided that it'd be best to just create a full on slippy 
map, using the normal stack, a-la switch2osm. I took some inspiration 
from OSM Then and Now as to the adjustable overlay, and followed an 
example on the Mapbox website.

You can see the result at https://maps.honeyfox.uk/. Bear in mind it is 
hosted on my home PC so don't expect it to be particularly performant or 
reliable, and it is limited to the UK.

Ideally you be able to adjust the time period the map shows, but I 
cannot see a way of achieving that without dropping the database and 
importing everything again, which is too demanding to be done on the fly.

Let me know if you have any thoughts or ideas :)

Cheers
George