dynamic-tiling

README

Dynamic Tiling

Precomputed mapbox vector tiles (MVT) come with size limitations or can impacted performance when trying to load too many points or complex polygons. In addition, it becomes difficult to make your geospatial data highly filterable when points have been dropped to meet tile size limitations. The goal of this project is to solve that by dynamically querying the data and serving up the tiles at varying levels of detail depending on zoom level.

Requirements

• postgres (tested using postgres@14)
  • extensions
    • postgis
    • h3 / h3_postgis (used to reduce points at higher zoom levels)

Optional

• redis-server

Environment Variables

Optionally can use .env file

# Required
POSTGRES_USER=[database host]
POSTGRES_USER=[database username]
POSTGRES_PASS=[database password]
POSTGRES_DB_NAME=[database name]

# Optional
POSTGRES_SSL_MODE=[database disable/require ssl] (default: require)
DEBUG=[enable/disable debug level logs] (default: false)
PORT=[port that dynamic-tiling service should listen on] (default: 8095)
REDIS_URL=[redis url] # i.e. redis://localhost:6379 
REDIS_CACHE_DURATION=[redis cache expiration] (default: 1h) # accepts anything that golang time.ParseDuration can parse 
ALLOWED_ORIGINS=[CORS space separated origins] (default: https://* http://*)
CACHE_CONTROL_HEADER=[Cache control header value] (default: private, max-age=300)
DISABLE_GZIP=[Disables gzip compression] (default: false)

Getting Startup

go build
./dynamic-tiling

There is also an optional parameter if you like to manage multiple .env files for different environments

./dynamic-tiling -env=staging 
# uses .env.staging file to load environment variables  

Usage

GET /mvt/{x}/{y}/{z}

Parameters

name	type	data type	description
x	required	integer	cartesian coordinate
y	required	integer	cartesian coordinate
z	required	integer	zoom level

Query Parameters

name	type	data type	description
query	required	string	SQL query for geospatial data
geoCol	required	string	Name of geospatial column (must be included in the final select of the SQL query)
srid	optional	integer	SRID for the geospatial column (default: 4326)

Responses

http code	content-type	response
200	application/x-protobuf	MVT protobuf binary

Usage Example

DeckGL Layer:

 const mvtLayer = new MVTLayer({
            id: 'walmartLayer',
            data: [
                'http://localhost:8095/mvt/{x}/{y}/{z}?query=SELECT id, name, location FROM my_geospatial_data&geoCol=location',
            ],
            minZoom: 0,
            maxZoom: 24,
            getFillColor: [255, 0, 0],
            getLineWidth: 1,
            pointRadiusUnits: 'pixels',
            getPointRadius: 5,
            stroked: true,
            getLineColor: [0, 0, 255],
            pickable: true
        }
    )