Some weeks ago an old friend of mine, Karim Homayoun, let me know of an event being held at swisstopo – the Swiss Federal Office of Topography in Bern – that was being organised as part of the European Heritage Days.
While Switzerland isn’t formally part of the EU, it is part of the Council of Europe, and so participates extensively in this important activity. There have been many such events throughout the country over the weekend.
There were two guided tours of swisstopo being organised – one in French in the morning and one in German in the afternoon – for 30 people each. I signed up for the morning session, and so took the train early on Friday morning to Bern’s Hauptbahnhof.
From there it’s a few minutes by tram to swisstopo’s main building in Wabern.
I was there a little early, so took a picture of the morning sun casting my shadow near a mural with silhouettes of people participating in various topography-related activities.
After everyone was assembled, we headed up for an introductory lecture by Karim.
Aside from the introduction, the tour had three parts, visiting the collections of instruments, photography and maps. We split into smaller groups, and my group went first with Karim to see the instruments.
The first display case was focused on measurement. Some of the brass instruments were simply gorgeous.
There were marine-oriented instruments, too, although unless they were used on lakes I don’t quite see how they were used within Switzerland. (A question that it didn’t occur to me to ask, at the time!)
Many of these devices had to be portable, as surveying has always needed to be “in the field”.
Which in the case of Switzerland, could also mean “on top of a mountain”.
It was interesting to see an image of the first triangulation network of Switzerland, made between 1825 and 1837. This would have been made using brass instruments measuring heights and distances of points on the top of mountains. One of the early reference points was apparently the Chasseral – in the foothills of the Jura, just north of Neuchatel – because it had already been measured by the French.
Being a big fan of stereoscopy in all its forms (from View-Masters to VR), I was happy to see it had been used here, too.
There was a section devoted to calculation, whether manual or electronic:
Later on photogrammetry – and specifically via aeriel photography – was used to capture the Swiss terrain more efficiently.
An American survey of the European continent was undertaken in 1946, and this included Switzerland. The generated dataset is available online, and is really interesting to see.
Somewhat more modern equipment was also included, including this Leica GPS unit from the turn of the millenium:
Another area of the exhibition focused on the tools for map production. From 1841 to 2000, some manner of engraving was used to create Swiss maps. It probably goes without saying, but each engraving had to be a negative, as it was then used to print on paper.
The first generation – used from 1841 to 1953 – was via engraving on copper plates, one for each colour.
The next generation went from using metal to using stone (which is very interesting in itself!). From 1866 to 1953, lithographic limestone was used for some maps, while copper plates were still used for others. Again, each colour was engraved on a separate block, allowing multi-colour printing via chromolithography.
From 1953 to 2000, resin-coated glass was used instead of metal or stone.
In around 1960, airbrushing was introduced as a technique to better render 3D information in maps (previously this had been done using either hatching or contour-lines and numeric altitude markers).
In 1925, offset printing was introduced as a mechanism for generating the physical paper maps.
After seeing the instruments used to capture the topography and to generate maps, we then spent time looking more closely at map generation approaches.
There were other, more local, maps on display, too.
The first, complete map of Switzerland is the “Dufour Map”, and was published between 1845 and 1865 (when modern Switzerland was founded).
Here are some separate limestone blocks used to print a map via chromolithography. This is the primary map, which would have been in black.
The waterways were a separate layer printed in blue, naturally enough.
The third layer was for rendering 3D, in a kind of pink:
Here’s the map that resulted from this process:
From here we went to a much cooler, humidity-controlled room that was focused on map restoration and storage. We were exposed to a litany of crimes committed against historic maps, over the years (glue, tape and staples are all bad news, for instance).
There were some really beautiful old maps mounted on the wall, here.
The last stop on the tour focused on the restoration and storage of photographic negatives, particularly from aeriel photography. The most problematic material here is celluloid, although care must also be taken with negatives on glass.
The bottom-right negative you see below was captured by an infrared-sensitive camera.
We were exposed to some celluloid that was degrading… the smell of vinegar was overpowering. Apparently they have to be very careful to detect damage that’s happening: much like with rotten fruit, it can spread very quickly within (or between) boxes of stored negatives.
Overall it was a fascinating morning. I learned a lot, and found the content of the session to be excellent. Many thanks to Karim and the whole team at swisstopo for all their hard work.
I went and captured a sequence of images of the map of my region of Switzerland from 1845 to 2018. It was fun to use another web app with a timeline (other than Dasher 360) for once! The sequence is very interesting, as it shows both the development of the region and the changes in mapping techniques, over the years.
Neuchatel is at an annex between mapping regions: it actually has four converging nearby, but the left and right maps always seem to get updated at the same time. The below animation shows that some years we have updates happening to the north (or the south) that are out of step. Which is also pretty interesting.
I’ve squished the resolution of the above animation, but you can download a larger 40MB version or a much larger 128MB version (I had to zip this latter one due to size limitations for GIF files on my blogging infrastructure). It’s also pretty cool to see the 2D map draped across the 3D topography – do check it out!
There’s a lot of activity being performed by swisstopo that wasn’t covered in this event, mainly because of the event’s focus on heritage rather than on more modern techniques that are used for reality capture and visualisation. I’m looking forward to learning more about their activities in these spaces, at some point!