Buildings · vector
Every building in Iberia: 14.9 million of them.
The outline of nearly every building in Spain and Portugal, from the VIDA Open Buildings dataset (built from Google, Microsoft and OpenStreetMap). The file is 3.8 gigabytes, the kind of dataset that crashes a server that tries to load it all. TerraServe just doesn't.
The approach
Read only what you look at.
Windowed reading
Most servers open a file by loading all of it into memory. That's impossible here. TerraServe instead keeps a tiny index of where each building sits, and when you look at a neighbourhood it jumps straight to just those buildings and reads only them. Opening the whole 3.8 GB file costs 4 megabytes of memory. A zoomed-in tile draws in 0.085 seconds, at full detail.
Bake the wide views, draw the close ones live
Zoom all the way out and a single tile suddenly touches millions of buildings. That's slow and heavy for anyone. So the wide, zoomed-out views are baked ahead of time into a compact archive (a zoomed-out tile that took 40 seconds live now serves in 0.42 seconds). Zoom in, where a tile only touches a few thousand buildings, and TerraServe draws it live on the spot.
How it's served
The exact command.
The real command behind the live demo. Notice how much shorter it is than cos2023: windowed reading means none of the memory-fitting flags are needed.
terraserve serve # 14.9M Iberia buildings, vector tiles --vector /data/IBERIA.fgb --vec-style /data/vida.sld --name vida --mvt-style /data/vida.mvt-style.json --pmtiles /data/IBERIA.pmtiles # the baked zoomed-out views (z0 to 10) --mvt-cache 512 --wms-cache 512 --max-inflight 8 --public-url https://terraserve.io/demo/vida/wms
| --vector | The data file: a FlatGeoBuf of 14.9 million building outlines. This format carries a built-in index, which is what makes windowed reading possible. |
| --vec-style | How to colour the buildings: an SLD style (here, coloured by which source each building came from). |
| --mvt-style | The matching style for the vector-tile view a browser draws itself. |
| --pmtiles | Trick 2. The pre-baked archive of the zoomed-out views (zoom 0 to 10), served straight off disk. It's read-only here, so no write-back flag is needed. |
| --mvt-cache 512 | Remember recently-drawn zoomed-in tiles (up to 512 MB) so revisiting a neighbourhood is free. |
| --wms-cache 512 | Same idea for the picture (WMS) view. |
| --max-inflight 8 | Draw at most 8 tiles at once, one per core, so a busy moment can't blow up memory. |
| --public-url | The public address to advertise to GIS clients, since it runs behind a web proxy. |
Measured: opening the 3.8 GB / 14.9 M-shape file uses 4 MB of memory; a zoomed-in tile renders in 0.085 s at full detail; a zoomed-out tile that took 40 s to draw live now serves from the archive in 0.42 s. This is the demo that would sink a load-everything server. Here, it runs on a small box.
Source. VIDA: Google-Microsoft-Open-Buildings, Iberia subset. Building footprints combined from Google Open Buildings, Microsoft Global ML Buildings, and OpenStreetMap.
In action
From all of Iberia down to a single building.
