survivaldeficit
Jan AdriaenssensUsing GPS in the year 1565
There’s a wonderful web app (“Allmaps Here”) that shows your GPS location on old maps. I love it.
https://www.verbeeld.be/2024/11/17/using-gps-in-the-year-1565/
Using GPS on old city maps 🗺️
There used to be a canal where this big white office building is now. I’ve taken this photo from the location of the pink dot on the map.
How to place your GPS location on an old map near you: https://www.verbeeld.be/2024/11/17/using-gps-in-the-year-1565/
This specific map of Antwerp can be found here: https://here.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmaps%2Fc3cc246df5ba4455
✅ Evert Albers
Martin Rundkvist@verbeeld Let me tell you, it's some serious work rectifying those old maps to modern real-world coordinates. A colleague and I have a paper coming up about the oldest known street network of Stockholm's suburbs.
@mrundkvist But so much fun too! I've learned so much about my own city by georeferencing these old maps I found online…
Josh Justice
Avi Rappoport (avirr)@verbeeld That looks fabulous!
Martin Jambon 🌍🌎🌏@verbeeld here's my location. The authors of the map didn't specify a publication date but it's ok because it's "correct".
https://here.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmaps%2F6fe39b2f7d71ae12
https://here.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmaps%2F6fe39b2f7d71ae12
Here's an early map of our area in 1866. Palo Alto didn't exist yet.
https://here.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmaps%2Fac78651595c7cc97
Palo Alto was founded in 1894. By 1926, the modern streets and schools were already there.
https://here.allmaps.org/?url=https%3A%2F%2Fannotations.allmaps.org%2Fmaps%2F410aa7f618181e9b
@mjambon Great thread, thanks! Cool maps too!
@mjambon You can always make the georeferencing of these "correct" maps even more correct, by using this editor: https://editor.allmaps.org/#/
(It's a rabbit hole… I'm spending way too much time there georeferencing and correcting old (local) maps…)
@verbeeld I'll give it a try when I'm at my desk. I'm curious about how it works:
- the wiki aspect: how are plain mistakes and vandalism undone?
- the precision and distortion aspects: what's the algorithm to map user-entered geographic coordinates to image coordinates using reference points?
- the wiki aspect: how are plain mistakes and vandalism undone?
- the precision and distortion aspects: what's the algorithm to map user-entered geographic coordinates to image coordinates using reference points?
@mjambon These things I don't know — I'm only a fan of the site, but I'm not maintaining it, sorry…
@verbeeld I'll investigate
@mjambon I have a similar project at https://onamap.me/
For the lat/lon to pixels algorithm, I use a triangulation of the reference points to interpolate u,v pixel coords based on pixel coords of nearby reference points
https://turfjs.org/docs/api/tin
@tim_fan cool. I don't have any need for it but I'm curious about dealing with bad data in practice and in theory. I.e. if one point is inconsistent with the majority, there should be a way to detect it and flag it. In practice, I suppose it depends on the application (e.g. are coordinates entered by a human who can make typos?).
@mjambon yeah I'm sure for my maps I make mistakes. All I do for error checking is to perform the forwards warping onto satellite imagery in QGIS, then visually check for discrepancies between the two. With this I can catch gross errors. E.g. overlay:
https://www.facebook.com/photo/?fbid=315155968310211
Beyond that, perhaps you could, on a per point basis, leave the point out of the referencing process, then see where it gets mapped to. If it is mapped far away from its reference location, perhaps the reference is wrong.
@tim_fan I suppose we could compare the Delaunay triangulations in both coordinate spaces and flag neighborhoods that are not preserved by the mapping.
Colin Haynes@verbeeld this is UK only but quite fun too. Best on a big screen rather than a phone.
Jerry van Kooten
Ken Fallon (PA7KEN, G5KEN)@verbeeld hi, very cool!
Wanted to share I've been doing something very similar since the start of last year.
I started doing this reverse geo referencing for hand-drawn tourist maps of towns, but also found it worked well for historical maps.
If anyone is in the UK, I've set up maps for London in 1561, Cambridge in 1575, and Oxford in 1605:
https://onamap.me/maps/London1561/
https://onamap.me/maps/Cambridge1575/
https://onamap.me/maps/Oxford1605/
I've been posting project updates on a facbook page:
https://www.facebook.com/me.onamap
Kasper Jordaens@verbeeld
Living on the edge of the map here, no surprise.But what a nice tool...
Living on the edge of the map here, no surprise.But what a nice tool...