Project Idea: Geo-referencing historic maps

[cityhubla]

Develop a workshop on Historic Maps such as the Sanborn maps from the Los Angeles Public Library and how to geo-reference them. Also offer resources and links to other map collections

[MtnBiker]

@cityhubla I have a bunch of kmz files that I must have got from you labeled "1888vol1.sanborn_geotiff.omaru." But they aren't the same 1888 maps that LAPL has. They don't seem to be 1894 either. They do load into Google Earth. But won't load into QGIS. Do you remember what these files are?

[MtnBiker]

Need

Putting scanned maps (originally of multiple sheets or pages) on a web page with location information. These are usually old (or otherwise they would be digital), but sometimes the map isn’t geolocated, that is, it may have coordinates on the map, but the computer can’t know about that information
Often multiple pages, for example, topographic maps, map guides such as Sanborn Insurance Thomas Brothers and Rand McNally. (I would expand on use cases and examples in an intro)
MaptimeLA Project ? Facilitate getting historical maps of LA tiles hosted. Sanborn—multiple editions (1888, 1894–1900, 1906-1950), Baist 1921, Thomas Bros., interesting tourist maps, bird's eye maps. [Note to self—check OSM historical]

Basic steps

1. Scan map(s) (this has already been done for many maps)
2. Georeference the scans so that the software knows the latitude-longitude of the maps (a few have already been done)
3. Create tiles and put them on a server (not aware of any of these). How are irregularly shaped originals made into tiles?
   Tiles is the standard method for putting maps on webpages

Challenges

1. no coordinates or other geo location information on the map.
2. geometrically inaccurate (even an very accurate old map may not be accurate enough for some uses today) or a copying distortion or wrinkling or shrinkage of paper maps.
3. Some streets realigned (Bunker Hill) or renamed.
4. most maps or scans have borders or other information (indexes, ads, logos, etc) that would cover or be unneeded on web page map (there may be an underlying map (OSM eg) that is either available making the scanned map more transparent or it is desirable to see the underlying map when the scanned map ends.
5. the problems described in item 3 are even more important when the web page is comprised of many pages or scans and the extraneous material overlaps the neighboring map,

Example project

1894 Sanborn maps for Los Angeles on a layered webpage. Here's an example of an an old scanned map: https://secure-shore-68966.herokuapp.com/map (page usually has to be refreshed to show the map).

Demo

Could add a layer(s) to The Oldest Surviving Los Angeles Restaurants project

Resources

1. LAPL among others has scans available on line. They have borders and in some cases a page has several pieces that represent different areas of the city, Requires a free account. None are georeferenced.
2. UCLA among others has georeferenced scans of some of these the Sanborn maps via the ProQuest Geo Edition. Only some are georeferenced because it seemed for about ⅓ of them only a jpg was available. Need to confirm if this was just a temporary server problem or something else). Omar has kml of these. Anyone can use at the library and students (alumni ?) can use online.
3. Mapbox for hosting tiles
4. Heroku and others for hosting web sites
5. QGIS georeferencing. Tutorial 1 and tutorial. Mapwarper can also be used for georeferencing, but since we're going to use QGIS in the next step we don't use it. But here's the info anyway MapWarper for georeferencing/georectifying, a [tutorial] and (http://history2016.doingdh.org/map-warper-tutorial/) and tile serving of the georeferenced map
6. QGIS tile making using QTiles.

[MtnBiker]

Should I upload the maps I've downloaded somewhere, so they can be linked to. Do we have such place? I'd also like to make a list of these resources. I have about 3 to 5GB concentrated around DTLA including Baist; 1888, 1894, 1906–1950 Sanborns; and other miscellaneous old maps. Some are georeferenced, but almost none are trimmed (or had the collars removed). Or do we just concern ourselves with the eventual tiles?

[techlady]

I recently talked to the reference librarian in Santa Monica. She is putting together historic geographical databases of SM residents based on several socioeconomic factors. She just found out about Maptime and wants to put her data "on the map."

[MtnBiker]

@techlady What kind of data and what kind of database?

[techlady]

Actually, I don't know. I just know that she is compiling historical data about people who lived in Santa Monica and linking it to addresses. She said she would be interested in coming to a Maptime meeting.

[MtnBiker]

Tiled-Historical-Maps project on GitHub

[techlady]

Greg, Interesting project, but you didn't say how one would go about georeferencing these maps. Charlotte At 12:00 PM 1/14/2017, you wrote:

<https://github.com/maptimeLA/Tiled-Historical-Maps>Tiled-Historical-Maps ­ You are receiving this because you were mentioned. Reply to this email directly, <#20 (comment)>view it on GitHub, or <https://github.com/notifications/unsubscribe-auth/ACWrdoGh9ut_4N5aqRaSBuvcWfz_3-iwks5rSSlBgaJpZM4KfJlz>mute the thread.

Charlotte Wolter 927 18th Street Suite A Santa Monica, California 90403 +1-310-597-4040 [email protected] Skype: thetechlady

[MtnBiker]

@techlady Georeferencing single sheet maps is fairly straightforward. In a program like QGIS you overlay the map on a current map and pick points that match on each. Look at Resources items 5 and 6. An finished example here. You may have to reload the page.

The problem that Omar is going to solve is how you take multi-page maps and put them together so they can be served as tiles. Omar is proposing after we work out the details we'll show the group how it's done and we hope interest them to work on other maps or projects using the maps we make available. There are many useful and nice looking maps that can be used.

[techlady]

Greg, Your link led to a Github page that had just a paragraph about the idea. No instructions on how to do it. By the way, where are the "Resources" that you mention? I see no link. Charlotte At 06:13 PM 1/14/2017, you wrote:

***@***.*** Georeferencing single sheet maps is fairly straightforward. In a program like QGIS you overlay the map on a current map and pick points that match on each. Look at Resources items 5 and 6. An finished example <https://secure-shore-68966.herokuapp.com/map>here. You may have to reload the page. The problem that Omar is going to solve is how you take multi-page maps and put them together so they can be served as tiles. ­ You are receiving this because you were mentioned. Reply to this email directly, <#20 (comment)>view it on GitHub, or <https://github.com/notifications/unsubscribe-auth/ACWrdn2SaZxnypRopxatfPqD2vonLXyjks5rSYDhgaJpZM4KfJlz>mute the thread.

Charlotte Wolter 927 18th Street Suite A Santa Monica, California 90403 +1-310-597-4040 [email protected] Skype: thetechlady

[MtnBiker]

Charlotte
Midway up the page (the third item) on GitHub is a long item by me that's summarizes what I know about the Project.
Sorry about the confusion.
If you're not seeing what I'm seeing what let me know.