Osm label server

Tool for serving OpenstreetMap (osm) points with a description label independet of the map tiles. The main purpose is serving the labels for rotation independent labeling of osm maps. It relies the data and api provided by the runtime_datastructure project. Datasets have to be provided in its format to be accesses by the osm label server.

Functions

The tool stats a server and answers requests at default at /label/<endpoint> with a geojson of the requested points. The request contains a bounding box and additional parameter for a selection of points to include. Example request (which requests all labels with t_min larger than 0.1):

GET http://localhost:8080/label/citynames?x_min=0&x_max=180&y_min=0&y_max=180&t_min=0.1

Endpoint parameters

The current parameters allow the setting of the bounding box and a filtering t value. The ordering as displayed in the example has to be used.

• x_min, x_max, y_min and y_max define the bounding box
• t_min allows only points with a t value larger than the given value

Response

The response is in the Geojson format. An example with one label is provided below:

{"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Point","coordinates":[8.7422973,53.051944500000005]},"properties":{"lbl_fac":26,"name":"Huchting","osm":30349113,"prio":121,"t":0.7067380674933035}}],"crs":{"type":"name","properties":{"name":"urn:ogc:def:crs:OGC:1.3:CRS84"}}}

Installation

For installation via building it yourself you will need a correctly configured go setup:

go get -u github.com/trump-fmi/osm_label_server

A precompiled binary is available under the current release. After extracting the tar.gz the server can be immediately started by using the start.sh as a default configuration and a default label file is included.

For correct startup the binary needs access to the shared library. So you need the following calls for startup:

LD_LIBRARY_PATH=LD_LIBRARY_PATH:$GOPATH/src/github.com/trump-fmi/osm_label_server/lib/
export LD_LIBRARY_PATH
./osm_label_server

Alternatively you can use the start.sh script located in the root directory of the project.

The server instance now runs and can be terminated by Control+C.

Configuration

The startup can be configured with parameters flags.

Flags

Flags can be set by "-flag value" or "-flag=value". If you want to keep the defaults, you do not have to supply anything.

Flag	Default value	Explanation
-endpoints	default.json	Path to the file with the endpoint configurations.
-port	8080	Port where the socket is opened.
-root	label	Root endpoint for the label providing endpoints.

Configuration file

The endpoint configuration is stored as json. For each endpoint the name and a path to a file is stored. The file contains the labels which should be provided at the endpoint.