Old Insurance Maps – Georeferencing Sanborn Fire Insurance Maps on Modern Maps

Posted by lapetitejort 7 days ago

Old Insurance Maps – Georeferencing Sanborn Fire Insurance Maps on Modern Maps(oldinsurancemaps.net)

74 points | 22 comments

okok3857 7 hours ago|

I developed and maintain this site so I am both very happy to see it get posted here and also watching htop intently...

I wanted to point out it is a crowdsourcing project, so every overlaid page you see has been placed there by a person, often through large institutional efforts at universities, but also individuals just looking to learn about their hometown through these old maps. Thanks for the interest!

_fs 2 hours ago||

Funny how this pops up on hacker news today. I have been working on an off and on again project in the same vein. But instead of sanford maps, I have been ripping and downloading GLO surveys. I now have about 3TB worth of 200k+ mid 1800 surveys done by the USGS (GLO at the time). My next step was to create a method of presenting this data. Do you think that your OHMG would help me here?

Its a similar problem that you faced, stripping off the extra image data from the map, then overlaying them on a base map. I might have a slightly easier time, since these surveys mostly line up to existing township/ranges of the PLSS, not at individual house/street level like the sanborn maps. I've manually done the process many times, most in ArcGIS, but have used a few others (like oldmapsonline). Your site was new to me, and the presentation looks great.

Here's an example of the type of survey I'm working with. https://www.oldmapsonline.org/en/maps/06317a09-5426-41e0-aa8...

okok3857 1 hour ago||

Thanks! Frankly the presentation side of the site needs a lot of work, and it's more about doing the georeferencing work, which sounds like you've already done. But you should get in touch I'd love to discuss further! I've done demo projects with old plat maps like you are working with.

jdmichal 2 hours ago|||

Something seems broken with the Tampa, FL map. I get an unauthorized page:

https://oldinsurancemaps.net/map/YK41FR

And this shows no volumes available:

https://oldinsurancemaps.net/viewer/tampa-fl/#/center/-84.77...

Same thing for Key West, FL.

okok3857 2 hours ago||

Yes, some maps in the site are hidden as they are part of an ongoing research project, just happens that Tampa and Key West are both examples of that. If you follow the blog/newsletter I'll surely announce when those are available.

garciansmith 6 hours ago|||

Thanks for making this, I look at Sanborns all the time doing historic preservation-related work.

Is there a way to quickly search for a specific address or select a point and then see the relevant map? Larger cities have Sanborns covering many volumes, and I see I can use sliders to turn them on and off to find the relevant one, but I wanted to make sure I wasn't missing a quicker way of finding a specific address.

okok3857 6 hours ago||

Great question: no. I've spent a lot more time making the georeferencing side of things work well than improving search and discovery, and even presentation (like the /viewer/ pages), of the maps on the site. It's something I hope to spend a lot more time on in the coming months. I know, dealing with those sliders is pretty cumbersome in big cities with many volumes (like SF).

garciansmith 5 hours ago||

Gotcha, no problem, just wanted to make sure I wasn't missing some obvious way. Still a super useful tool, thanks again.

bduhan 3 hours ago|||

Great work! I started georeferencing old plat maps and aerial photographs from my area in QGIS and realized quickly it would be hard to ask other for help without a platform like this.

I’ll try running my own and see about importing existing work. Have you thought about extending the public site scope beyond insurance maps?

okok3857 2 hours ago|||

Yes, at certain points, like when I made that ohmg.dev website, I have looked at this as a re-deployable platform that anyone could self-host. It still technically is, but I've slowed down a lot on that idea (no one really showed up with interest). There are other good places to georeference maps on the web, like mapwarper.net and allmaps.org. That said, I do hope to expand to handle import of other atlases, not only Sanborns, and if you have something particular in mind you can mention it here: https://github.com/ohmg-dev/OldInsuranceMaps/issues/266

lapetitejort 3 hours ago|||

> Have you thought about extending the public site scope beyond insurance maps?

The maintainer is generalizing outside of Sanborn maps [0].

[0]: https://www.ohmg.dev/

dmd 5 hours ago|||

Do you use IIIF for this? Do you know about https://allmaps.org/ ?

okok3857 4 hours ago||

No (or, not yet...) and yes, I know the Allmaps team well--it is an excellent project. There are a lot of similarities, but I would say two high-level differences are 1) OIM is built around server-side processing that immediately produces downloadable files and web services (geotiffs) while Allmaps applies a client-side transformation to non-geo IIIF tiles, and 2) OIM is designed around the creation of mosaics from many different pages to a greater extent than Allmaps is. This year I do see bringing more IIIF/Allmaps tooling into OIM though, so stay tuned!

selimthegrim 6 hours ago||

Hi Adam! Adam runs really fun events where you get to help him annotate the maps if you’re ever in the New Orleans area

okok3857 6 hours ago||

Hi! I added a page about "georeference-a-thons" recently here: https://oldinsurancemaps.net/community-georeferencing/

lapetitejort 7 days ago||

Sanborn Fire Insurance maps document cities in extreme detail. Not only are the positions and shapes of buildings accurately mapped, but also rough outlines of the rooms, their construction materials, and even small details like if the building hired a night watchman. See downtown San Fracisco for example: https://oldinsurancemaps.net/viewer/san-francisco-ca/?sanbor...

devilbunny 7 hours ago||

Also a major plot point in Peng Shepherd's novel The Cartographers. Not a marvelous novel (though it's far better than anything I could write), but entertaining enough and an easy read.

Forgeties79 8 hours ago||

They’re super fun to look at if you have live in an historic home.

jojohack 6 hours ago||

Thanks for sharing. I went through a similar process recently, manually stitching together fire insurance maps from my hometown. A large part of the business district burned down in 1916, but maps from a couple of years earlier survived. It worked, but it was tedious. This would have saved a lot of time. Here's the link if anyone wants to check it out: https://fire.gorch.com/

okok3857 1 hour ago|

Thanks for sharing, this is really nice. I've added it to the list of other projects I have on the site [0]. Feel free to get in touch if you want to use OIM for other years of Paris, TX.

[0] https://oldinsurancemaps.net/more-about-sanborn-maps/

chiffre01 6 hours ago|

Clicking on a lot of the maps gives me this ? I'm logged in as well

Unauthorized: You do not have access to this item.

okok3857 6 hours ago|

Yes, there are a number of maps (the FHA ones and also one Sanborn) that are part of a research project that is still in the works, so they are hidden for now.