Wednesday, August 07, 2013

What would Google Maps for Toronto look like in 1858?

It amuses me to present the following zoomable, scrollable online version of the 1858 Boulton Atlas of the City of Toronto and Vicinity, surveyed and compiled by W.S. and H.C. Boulton.

Scroll around, and zoom in & out using your mouse—just like you would in Google maps!

View the map in full page mode here.

I’m not sure how useful this is as a historical tool, but it merits at least 30 seconds’ worth of hey this is neat. Try your scroll wheel! (Sorry iPad users; this demo requires a full featured browser)

Thanks go to Carrie Martin for volunteering to help stitch this together and putting up with my nattering edits.

[Note: if you’re into historical maps, you might want to check out my larger projects:

Update: Media Coverage

This post generated a fair amount of online discussion and coverage. Here’s a sample of the chatter:
and a mention on the CBC Metro Morning show:

The Background Story

Earlier this spring, I made an online gallery of the Boulton Atlas, a set of 30 detailed map plates of Toronto created in 1858 by WS Boulton.

But I wasn’t entirely satisfied with the way it was presented. Although I created a key map to help users, I still found it awkward to look up an individual plate.

I wanted to make a composite version of the Atlas—that is, to stitch together all of the plates to form a super-map of the entire city.

Of course I’m not the first person to have this notion. In 2009 E.R.A. Architects created a huge wall-map version for their Harbourfront exhibit, Found Toronto.

I asked the kind folks at E.R.A. if they still possessed the original file from the exhibit, and if I could acquire it to put online. They were extremely helpful, and graciously took the time to search for it, but unfortunately, all they had left on their system was a low resolution copy.

Similarly, a composite was done for the book Historical Atlas of Toronto by Derek Hayes, but the resolution was scaled down (as it only needed to fit in a coffee-table size book) and all the useful detail was lost.

So, I decided to recreate my own stitched-together-version. Lacking a computer with sufficient horsepower, I inveigled my friend Carrie to help me out — she actually did the labour. Thanks again Carrie! [A small nod also goes to the several others who volunteered to assist]

The resulting image is modestly hefty—24,108 x 11,405 (about 275 megapixels) in size.


There were some unavoidable issues and compromises.

The Boulton maps are each lithographed onto separate physical plates. Although they are ostensibly all drawn at the same scale, they are not exactly so (at least not with modern precision in mind). As well, the physical plates have aged differently depending on their individual exposure to light and air, resulting in colour contrasts between plates. Finally, the digital scans to which I had access were not all at the same scale (major pain in the neck!).

As a result, the stitching is far from seamless. Imagine putting together a puzzle where the pieces don’t actually fit together.

We tried our best to preserve alignments where possible, but (deliberately) sacrificed accurate placement along certain streets/seams. Subtle changes in scan orientation wind up being grossly magnified when trying to stitch together multiple plates.

In my view the sole truly egregious problem is just east of Carlton and Parliament; the street formerly known as Elm gets semi-obliterated; everything else is ‘close enough’. Queen and (the modern) College St., being the two horizontal seams, suffer the most. Meanwhile several north/south streets (e.g. Yonge) are allowed to wax and wane in width (to a degree that some may find disturbing) in order to force neighbouring streets to align correctly.

I’m comfortable with the minor distortions introduced; it’s a lot harder than it looks! If you think you can do a better job, you’re welcome to download the plates and try it yourself. Anyway, please blame Carrie for any errors (haha).

The scan images are courtesy of the Toronto Public Library: 912.71354 B594 1858.


[personal aside to any geographers / cartographers out there: Yes, I know this should properly be done as some kind of layer in ArcGIS, then re-made into new map tiles, for browsing via open street maps or whatever, which would allow all kinds of interesting data overlays etc. You are cordially invited to invest the effort to do so. I’ll probably get around to it, if and when ceases working.]