Preparing venue maps
How a floor plan or site drawing becomes a georeferenced, offline-capable map layer.
The site plans on the SCAD Maps map are not photographs or hand-drawn overlays. They are your own CAD drawings, converted into georeferenced map layers that line up with the real world to the centimetre and can be downloaded for offline use. This page explains how a drawing becomes a layer, what an operator has to put on the server, and how the same layers reach phones with no signal.
From drawing to layer#
- Draw. The site plan lives in CAD in a known coordinate system. The Dutch national grid (RD, EPSG:28992) and the Belgian Lambert 72 grid (EPSG:31370) are supported; a layer without an explicit system is read as RD.
- Plot. The drawing area is plotted to four picture quadrants together with the map coordinates of their corners. Splitting into quadrants keeps the images at a size the tools can handle, and all four are shown as one layer.
- Tile. Each picture is cut into a pyramid of small WebP tiles, from wide overview levels down to zoom 22. Tiles that would be empty are left out, and the server answers a request for one with a transparent tile.
- Package. The tiles are bundled into a single archive per quadrant, in PMTiles format. SCAD Maps reads it directly, so no tile server and no unpacking is needed.
- Publish. The archive goes onto the instance, either by an administrator in the dashboard or by the operator on the server.
The plan keeps the name of the drawing. Layers appear in Map Layers in the dashboard where you set their order, opacity, default visibility and audience; see Map layers and views.
Publish from the dashboard#
The easy route is the Upload SCAD Map button in Map Layers. A .scadmap file is a tile archive with the map bounds and coordinate system written into it, so it needs no separate bounds list. Only a full Admin can upload, files may be up to 2 GB, and the server checks the bounds before publishing. It never overwrites an existing layer of the same name: rename the file first. The layer is new for everyone the moment it is published, and people see it after a reload.
Publish on the server#
Operators with server access can place files directly. The tiles folder of the instance holds:
| What | Where | Purpose |
|---|---|---|
| Live archives | pmtiles/, one .pmtiles or .scadmap file per quadrant | What the map streams. The layer list picks them up on the next request; no restart. |
| Loose tiles | tiles1024/<name>/<z>/<x>/<y>.webp | The fallback for layers without an archive, and the source for the offline packs. |
| Bounds list | image_bounds.csv in the images folder | Only for archives that do not carry their own bounds. Semicolon-separated rows of image name, bottom-left corner, top-right corner and coordinate system. A last number sets the default stacking, high for site plans and 0 for underlays. |
| Offline packs | tiles_z18.zip to tiles_z21.zip | What phones download for offline use. |
Quadrants are grouped into one layer by their name: a trailing _r0c0, _r0c1, _r1c0 or _r1c1 is ignored when the layer name is worked out. A layer's name in the list is the drawing name without it.
Who may see a layer#
Every layer can be limited to certain custom roles or people. The restriction is enforced where the tiles are served: someone who is not allowed to see a plan cannot fetch its tiles, whichever address they try. Offline packs contain every layer, so they are only granted to people who may see all of them. Everyone else downloads the maps they are allowed, one layer at a time.
Offline packs#
An offline pack is a plain archive of the loose tiles up to a zoom limit. Each pack contains everything below its limit, so the larger ones include the smaller ones.
| Pack | Quality shown in the app | Detail |
|---|---|---|
| Zoom 18 | Very low | Overview only. |
| Zoom 19 | Low | Streets and large structures. |
| Zoom 20 | Medium | The default. Good enough for most site work. |
| Zoom 21 | High | Fine detail. The largest of the packs, up to a few hundred megabytes for a big site. |
| Full | Full offline map | Every zoom level, straight from the PMTiles archives. Only offered when the instance has them. |
Packs are rebuilt on the server after new tiles arrive. Rebuilding is fast there because the tiles are already on local disk, and it is far slower to do on a laptop, so packing is best left to the server. Devices that already downloaded a venue see the new version and replace the old one on their next download. How people install and use the packs is described in Mobile use and offline.
Check the result#
- Open the layer list. The new plan should be listed with the right name and tag, and appear where you expect it on the map.
- Zoom in to the highest level around a known corner. A layer that sits a few metres off has the wrong coordinate system or swapped corners in its bounds row.
- Sign in as a person who should not see it and confirm it is absent.
- On a phone, download the venue and switch on the offline-only mode to confirm nothing is left blank.
Layer display can also be tuned per instance; see Instance configuration.