By Gaetan Boisson
We often say that all good things come to an end, but when the end loomed over our most popular Digital Scholarship (DS) project, our DS Team members put their minds together to save it!
Historical Maps of Singapore (found on libmaps.nus.edu.sg) is a project done in collaboration with the Department of Geography. 31 historical maps were digitised and georeferenced by a team of specialists, and a user interface was built to allow users to explore this collection. It is frequently used in classes, projects, featured at the URA gallery and even in the media!
To keep the project running required a dedicated server, close to 400GB of storage space, specialised software and an operating system.
However, we were informed that the operating system had reached its end-of-life, and the server would have to be decommissioned.
On hearing this, the DS Team immediately started exploring ways to preserve the facility and make it more sustainable. Thorough research led us down the rabbit hole of geospatial raster data, where images aren’t what they seem. While many would consider online maps as being mere images, GIS data is in fact much more subtle than this, as the integration of proper geospatial information needs to be accounted for! This usually leads to very heavy technical requirements and the need for specialised software on the server side – something we wanted to avoid as we were committed to building sustainable projects.
Thankfully, geographers have been working on this issue as well, and we discovered a simpler solution was already created – Cloud Optimised Geotiffs. With some clever engineering and data preparation, we will be moving from a dedicated server with specialised software requiring 400GB of space to a very simple website hosted on a standard web server. Best of all, this solution only requires less than 3GB of space in total, a reduction of over 99% of the original size!
But wait, there’s more! In the process of transforming this data and gaining a better understanding of GIS raster data, we managed to correct some of the issues we had on the previous platform.
We will now have more consistent colors on our maps, in particular those made of several sheets.
Before: Old maps with inconsistent colour
After: New maps with better colour grading
And, some areas that appeared wrongly as transparent will now be showing their actual original color!
Before: Some pixels are wrongly rendered as transparent
After: These areas now appear as a clean sheet!
Cloud Optimised Geotiffs enables more efficient workflows on the cloud, translating to greater ease in management and storage on our end, and faster display for end users. We are now in the midst of rebuilding the interface and we can’t wait to unveil the completed works in the coming months!
