OpenStreetMap Tile Server (OTS)

OTS is a server that loads OpenStreetMap data file (*.osm.pbf) into memory then generates map tiles for HTTP requests.

Compile & Packaging

• checkout source codes

$ git clone https://github.com/OutOfBedlam/ots.git

$ cd ots

• compiled executable binary will be created in ./tmp

$ make

Start OTS as tile-rendering-server and OSM data-server in a process

You need to download osm.pbf file from OpenStreetMap sites
https://wiki.openstreetmap.org/wiki/Planet.osm#Country_and_area_extracts

Current version of OTS loads whole map data into memory, so make sure your osm.pbf file is size enough to fit system memory.

./tmp/ots server -p 1918 -i ./tmp/my-area.osm.pbf 

sequenceDiagram
autonumber
   Note over Browser, OTS: HTTP (ex: leaflet.js)
   Browser ->>+ OTS : http://server_addr/tiles/{z}/{x}/{y}.png
   OTS->>OTS: Convert coords
   OTS->>OTS: Retrieve map data
   OTS->>OTS: Gen image
   OTS ->>- Browser: .png

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Start tile-rendering-server and data-server

• start a process as a data-server

./tmp/ots server -p 1918 -i ./tmp/my-area.osm.pbf 

• start tile-rendering-server

Specify the endpoint of data-server instead of *.osm.pbf file with -i

./tmp/ots server -p 1919 -i tcp://127.0.0.1:1918

• then web browser can retrieve map tiles as following flow

Web browser --> 127.0.0.1:1919 (rendering server) --> 127.0.0.1:1918 (data server)

sequenceDiagram
autonumber
   Note over Browser, Render-Server: HTTP (ex: leaflet.js)
   Browser ->>+ Render-Server : http://server_addr/tiles/{z}/{x}/{y}.png
   Render-Server->>Render-Server: Convert coords
   Render-Server ->>+ Data-Server : request map data with lat/lon bounds
   Note over Render-Server, Data-Server: GRPC
   Data-Server ->>- Render-Server: map data (osm features)
   Render-Server->>Render-Server: Gen image
   Render-Server ->>- Browser: .png

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Configuration file

edit and copy server-config-sample.hcl, keep file extension as *.hcl. then apply the path with -c argument.

./tmp/ots server -c <config_file.hcl>

config file items

item	desc	ex
pname	process instance name	"ots01"
osm-data-source	data file or data server address	"./data.osm.pbf" "tcp://localhost:1918"
bind	listening address	"127.0.0.1"
port	listening port	1919
grpc.max-recv-msg-size	grpc limit (MB)	100
grpc.max-send-msg-size	grpc limit (MB)	100
log.console	log output to console	true false
log.filename	log file path
log.default-prefix-width		10
log.default-level	log level	"TRACE"
http.console-color	colored http log	true false
http.debug-mode	debug http log	true false
httplog.console
httplog.filename
httplog.default-prefix-width
httplog.default-level

rendering server only items

item	desc	ex
cache-size	size of lru cache	2000
show-watermark	watermark (tile coordinates) on tiles	true false
show-labels	enable labels	true false

All items in config file can be override by command line arguments. the name of argument is same as config item with double dash --. For example, to override port number ots -c my-config.hcl --port=2929, port number 2929 will be applied.

Where to download *.osm.pbf files

ex) Download south korean osm.pbf file

• https://download.geofabrik.de/asia/south-korea.html

• OSM data up to 2022-04-17T20:21:54Z. File size: 148 MB;

• https://wiki.openstreetmap.org/wiki/Planet.osm#Country_and_area_extracts

References about osm.pbf files

• https://wiki.openstreetmap.org/wiki/Elements

• https://wiki.openstreetmap.org/wiki/PBF_Format

• Nodes : https://wiki.openstreetmap.org/wiki/Node

• Ways : https://wiki.openstreetmap.org/wiki/Way

• Relations : https://wiki.openstreetmap.org/wiki/Relation