Making Open Geospatial Data Useful
Spatial Talks and Network #21, November 2025
If you can’t see the screen, slides are at
letstalkspatial2025.diagramchasing.fun
My background
What is ‘useful’ open geospatial data?
What is geospatial data?
There are many geospatial portals
There is lots of geospatial data
Sometimes there is too much data
What is open geospatial data?
- Available for free
- Downloadable
- Reusable
Some people may have more specific definitions of ‘open’ geospatial data.
Example: OpenStreetMap
Free, downloadable, reusable
Use however you want
Visualize however you want
Extend however you want
Transform however you want
Bonus with OpenStreetMap: Contribute whatever you want
How is this different from Google Maps?
Google Maps cannot be inspected like OpenStreetMap can.
Google Maps cannot be controlled like OpenStreetMap can.
What is ‘useful’ open geospatial data?
able to be used for a practical purpose or in several ways
Is it not ‘useful’ already?
How would I use this geospatial data for a practical purpose?
Can it be used to solve a problem in my daily life?
Problem 1
Flooding in Bengaluru
Which areas are prone to flooding?
Which areas are prone to flooding?
Start with a Google Search
First link has a a dataset with Flooding Locations
Second link has an image that is tough to orient myself on
3 years ago, the wisdom of Reddit suggested the same image
Do some more research
find out about topographic maps
It would be nice to overlay the Flooding Locations on an inverted topographic map
The topographic map site has an Elevation API
But you have to pay for it!
As someone who has worked with GIS, I know I can get a DEM file in a GIS software like QGIS
But that is a high friction and technical process for the average person
Anyone should be able to easily view Flooding Locations on an interactive map
- On a mobile device
- Without having to install any app
- Without needing to know how to use DEM files
Technical Details
- DEM (Copernicus GLO-30 DEM)
- WhiteboxTools for hydrological processing
- PMTiles for vector tiles
- MapLibre for the map
- SvelteKit for the website
- Netlify for the cloud hosting
Problem 2
or Problem 1 (Part 2)
Governance in Bengaluru
Which agency dug up this road?
Why is BWSSB(?) not fixing the flooding in my area?
Who is my local MLA?
What police station jurisdiction do I come under?
(Hopefully GBA will simplify or make these questions less important)
What police station jurisdiction do I come under?
What police station jurisdiction do I come under?
Bharathi Nagar Police Station?
None of the results are relevant to the query
City Police website has no spatial or map component to it, but does have contact details of police stations
KGIS Portal claims to have dozens of map layers, but none of them seem to be clickable
Neither City Police website nor KGIS Portal were “useful” for the query
And this is not unique to City Police.
- BBMP/GBA
- BWSSB
- BESCOM
- Revenue Department
- Elected Representatives
It would be nice to have a map with jurisdiction boundaries for all of them
As someone who frequently uses government websites and geospatial portals, I know how I can get the data I need
But that is a high friction and technical process for the average person
Anyone should be able to easily find their local government information on a map
- On a mobile device
- Without having to install any app
- Without needing to know how to extract data from a geospatial portal
Technical Details
- GeoJSONs for each Department sourced from different sources
- Combined into single TopoJSON
- MapLibre for the map
- SvelteKit for the website
- Cloudflare for the cloud hosting
Problem 3
or Problem 1 (Part 3)
Getting around in Bengaluru
Suppose:
- I don’t want to mentally and physically drain myself navigating traffic
- On a single day, I need to go to multiple places in the city
- I don’t want to spend 1000s of rupees on autos/cab ride
Solution: Use public transport
Easier said than done
Much deeper problem that won’t be solved unless there is a fundamental mindset shift in how the city and government thinks about mobility
How can I simplify my public transport commute for now?
How can I simplify my public transport commute for now?
Transit direction with multiple destinations are not supported
No live tracking
Official app for BMTC
Not very user friendly
In an ideal world, BMTC would be spending their limited resources on their core competence, not on apps
If the data and live tracking was publicly available, this would be a non-issue
And this is not unique to BMTC
Luckily there are already open source tools that handle the tech
How to build such a tool for Bengaluru?
- Fork BusRouter SG
- Add in BMTC data
Technical Details
- Scraped BMTC data and generated GTFS feed
- Cloudflare Pages Functions as middleware to fetch live tracking information from the BMTC API
No technical knowledge needed to build such a tool for any city
It’s already open source and free
Problem 4
or Problem 1 (Part 4)
History of Bengaluru
How urbanized was my area in 1920?
How urbanized was my area in 1920?
Finding old maps of any place in India is a challenge
Ironically, the oldest government department of India is the department that makes maps
The biggest challenge is finding and sourcing the maps
Once you find them, they can easily be made accessible on a map
Technical Details
- PNG/TIFF digital scans sourced from multiple places
- Georeferenced and saved as GeoTIFF using QGIS
- MapLibre for the map
- SvelteKit for the website
- Cloudflare R2 for storing the tiles
Closing Notes
Flooding in Bengaluru
Without DEM data and Flooding Locations, there is no BLR Water Log
BLR Water Log can be recreated anywhere if data is available
Flooding in Bengaluru Flooding
Without DEM data and Flooding Locations, there is no BLR Water Log
BLR Water Log can be recreated anywhere if data is available
Governance in Bengaluru
Without administration jurisdiction boundaries, there is no BLR City Officials
BLR City Officials can be recreated anywhere if data is available
Governance in Bengaluru Governance
Without administration jurisdiction boundaries, there is no BLR City Officials
BLR City Officials can be recreated anywhere if data is available
Governance in Bengaluru Governance
Without administration jurisdiction boundaries, there is no BLR City Officials
BLR City Officials can be recreated anywhere if data is available
Public Transport in Bengaluru
Without public transport data, there is no TransitRouter
TransitRouter can be recreated anywhere if data is available
Public Transport in Bengaluru Public Transport
Without public transport data, there is no TransitRouter
TransitRouter can be recreated anywhere if data is available
Public Transport in Bengaluru Public Transport
Without public transport data, there is no TransitRouter
TransitRouter can be recreated anywhere if data is available
History in Bengaluru
Without old maps being available, there is no BLR Yesterday
BLR Yesterday can be recreated for any city if maps are available
History in Bengaluru History
Without old maps being available, there is no BLR Yesterday
BLR Yesterday can be recreated for any city if maps are available
History in Bengaluru History
Without old maps being available, there is no BLR Yesterday
BLR Yesterday can be recreated for any city if maps are available
All 4 of these sites were built in the past 365 days
If data is available, all 4 of them can be built for a new city in a week
Thanks for listening!
osm.org/user/Vonter
diagramchasing.fun