https://github.com/fogleman/density
Render millions of points on a map.
https://github.com/fogleman/density
Last synced: 11 months ago
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Render millions of points on a map.
- Host: GitHub
- URL: https://github.com/fogleman/density
- Owner: fogleman
- License: mit
- Created: 2016-04-07T19:21:15.000Z (almost 10 years ago)
- Default Branch: master
- Last Pushed: 2019-12-28T16:30:12.000Z (about 6 years ago)
- Last Synced: 2025-04-01T20:12:13.489Z (12 months ago)
- Language: Go
- Homepage: https://www.michaelfogleman.com/static/density/
- Size: 20.5 KB
- Stars: 147
- Watchers: 6
- Forks: 14
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# High-density Point Maps
Render millions of points on a map.
### Demo Site
This demo shows 77 million taxi pickups in NYC - from January to June 2015.
https://www.michaelfogleman.com/static/density/
### Dependencies
- Go
- Cassandra
### Download
go get github.com/fogleman/density
### Loading Data
Cassandra is used to store large amounts of data. Data is clustered by `(zoom, x, y)` so
that all of the points inside of a tile can quickly be fetched for rendering, even
faster than PostGIS with an index.
First, create a new keyspace and table to house the data.
create keyspace density
with replication = {
'class': 'SimpleStrategy',
'replication_factor': 1
}
and durable_writes = false;
create table points (
zoom int,
x int,
y int,
lat double,
lng double,
primary key ((zoom, x, y), lat, lng)
);
Next, load points into the database from a CSV file using the loader script.
go run loader/main.go < input.csv
Several command line options are available:
| Flag | Default | Description |
| --- | --- | --- |
| -keyspace | density | Cassandra keyspace to load into |
| -table | points | Cassandra table to load into |
| -lat | 0 | CSV column index of latitude values |
| -lng | 1 | CSV column index of longitude values |
| -zoom | 18 | Zoom level to use for binning points |
Just run the loader whenever you need to insert more data.
### Serving Tiles
Once the data is loaded into Cassandra, the tile server can be run for rendering tiles on the fly.
go run server/main.go
| Flag | Default | Description |
| --- | --- | --- |
| -keyspace | density | Cassandra keyspace to load from |
| -table | points | Cassandra table to load from |
| -zoom | 18 | Zoom level that was used for binning points |
| -port | 5000 | Tile server port number |
| -cache | cache | Directory for caching tile images |
### Serving Maps
A simple Leaflet map is provided to display a base map with the point tiles on top in a separate layer.
cd web
python -m SimpleHTTPServer
Then visit [http://localhost:8000/](http://localhost:8000/) in your browser!
### TODO
- tile rendering options
- multiple layers