Mapping Brunei
Presented at Brunei Geek Meet
So there was this data hack day we had last month....
I <3 Buses
I Got Invested
Until....
Firdaus reminds me...
Survey Dept
Them Data!
Why Mukim and Kampong data?
Where am I?
Mukims
The Data
Wait what is this data?!?!?
What is this?
Take me to 4.535277,114.727669
The Rabbit Hole Begins
Danger
Acronyms and head aching words ahead!
What is this?
EPSG 29873
EPSG: European Petroleum Survey Group
- Scientific organization with ties to the European petroleum
- Compiled and disseminated the EPSG Geodetic Parameter Set, a widely used database of
- Earth ellipsoids
- Geodetic datums
- Geographic and projected coordinate systems
- Units of measurement
- etc
World Geodetic System (WGS)
Standard in cartography, geodesy, navigation including by GPS
Standard coordinate system for the Earth
Latest revision is WGS 84 (aka WGS 1984, EPSG:4326), established in 1984 and last revised in 2004
WGS 84 is the reference coordinate system used by the Global Positioning System
WGS 84
Web Mercator
a.k.a Google Web Mercator, Spherical Mercator, WGS 84 Web Mercator or WGS 84/Pseudo-Mercator
De facto standard for Web mapping applications. It rose to prominence when used in the first Google Maps in 2005.
Official EPSG identifier is EPSG:3857
WGS 84 Web Mercator
WGS 84 Web Mercator
sr-org projection 7483
epsg projection 3857
WGS 84
epsg projection 4326
Geographic coordinate systems (lat/long) are based on a spheroidal surface that approximates the surface of the earth
A datum typically defines the surface and the position of the surface relative to the center of the earth
A projection is a series of transformations which
- converts the location of points on a curved surface (the reference surface or datum)
- to locations on flat plane (i.e. transforms coordinates from one coordinate reference system to another)
http://gis.stackexchange.com/questions/664/whats-the-difference-between-a-projection-and-a-datum
What's the difference between a projection and a datum?
Two components of a Coordinate System
1. A Geographic Coordinate System or GCS
GCS is used to define your real world points on a 3 dimensional digital surface
WGS84 falls under a GCS
2. Projected Coordinate System or PCS
PCS takes points defined with your GCS and translate them to a 2-dimensional surface
This is what people commonly refer to as a "projection"
http://gis.stackexchange.com/questions/149749/is-wgs84-a-coordinate-system-or-projection-system
Is WGS84 a Coordinate system or projection system?
- Google Earth: geographic coordinate system. wgs84 datum. (EPSG: 4326)
- Google Maps: projected coordinate system. wgs84 datum. (EPSG 3857)
- Open Street Map database: geographic coordinate system with units decimal degrees & datum of wgs84. (EPSG: 4326)
- Open Street Map tiles and WMS webservice: are in the projected coordinate system that is based on the wgs84 datum. (EPSG 3857)
-
Further confusing:
- often map is in Web Mercator(EPSG: 3857)
- actual coordinates used are in lat-long (EPSG: 4326).
EPSG 3857 or 4326 for GoogleMaps, OpenStreetMap and Leaflet
Even More formats
degrees minutes seconds: 40° 26′ 46″ N 79° 58′ 56″ W
degrees decimal minutes: 40° 26.767′ N 79° 58.933′ W
decimal degrees: 40.446° N 79.982° W
EPSG 29873: Survey Dept
EPSG: 3857 WGS 84 Web Mercator
EPSG: 4326 WGS 84
Transform Fail
Proj4js
JavaScript library to transform coordinates from one coordinate system to another, including datum transformations
WKT: Well-known text
-
Markup language for representing vector geometry objects on a map, spatial reference systems of spatial objects and transformations between spatial reference systems
-
WKB: well-known binary
-
A binary equivalent of WKT.
-
For databases: PostGIS, Microsoft SQL Server, DB2
-
-
Formats defined by the Open Geospatial Consortium(OGC)
+proj=omerc +lat_0=4 +lonc=115 +alpha=53.31582047222222 +k=0.99984
+x_0=590476.87 +y_0=442857.65 +ellps=evrstSS +units=m +no_defs
PROJCS["Timbalai 1948 / RSO Borneo (m)",
GEOGCS["Timbalai 1948",
DATUM["Timbalai_1948",
SPHEROID["Everest 1830 (1967 Definition)",6377298.556,300.8017,
AUTHORITY["EPSG","7016"]],
AUTHORITY["EPSG","6298"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4298"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
PROJECTION["Hotine_Oblique_Mercator"],
PARAMETER["latitude_of_center",4],
PARAMETER["longitude_of_center",115],
PARAMETER["azimuth",53.31582047222222],
PARAMETER["rectified_grid_angle",53.13010236111111],
PARAMETER["scale_factor",0.99984],
PARAMETER["false_easting",590476.87],
PARAMETER["false_northing",442857.65],
AUTHORITY["EPSG","29873"],
AXIS["Easting",EAST],
AXIS["Northing",NORTH]]
Human-Readable OGC WKT
Proj4
coord = [114.71360430047, 4.6084126066456]
// based on place on map at http://spatialreference.org/ref/epsg/29873/
console.log("Input Coordinates :"+
" 114.71360430047 , 4.6084126066456");
console.log("Output Coordinates :"+
" 558706.105088 , 510127.869649");
console.log("-----------------------------------------------------"+
"----------------------------------------");
// http://openlayers.org/en/master/examples/scaleline-indiana-east.html
// http://spatialreference.org/ref/epsg/29873/prettywkt/
proj4.defs('BN',
'PROJCS["Timbalai 1948 / RSO Borneo (m)",'+
'GEOGCS["Timbalai 1948",'+
'DATUM["Timbalai_1948",'+
'SPHEROID["Everest 1830 (1967 Definition)",6377298.556,300.8017,
'+'AUTHORITY["EPSG","7016"]],'+
'AUTHORITY["EPSG","6298"]],'+
'PRIMEM["Greenwich",0,'+ 'AUTHORITY["EPSG","8901"]],'+
'UNIT["degree",0.01745329251994328,'+'AUTHORITY["EPSG","9122"]],'+
'AUTHORITY["EPSG","4298"]],'+
'UNIT["metre",1,'+'AUTHORITY["EPSG","9001"]],'+
'PROJECTION["Hotine_Oblique_Mercator"],'+
'PARAMETER["latitude_of_center",4],'+'PARAMETER["longitude_of_center",115],'+
'PARAMETER["azimuth",53.31582047222222],'+
'PARAMETER["rectified_grid_angle",53.13010236111111],'+
'PARAMETER["scale_factor",0.99984],'+
'PARAMETER["false_easting",590476.87],'+'PARAMETER["false_northing",442857.65],'+
'AUTHORITY["EPSG","29873"],'+
'AXIS["Easting",EAST],'+'AXIS["Northing",NORTH]]'+
'');
console.log("ol.proj.fromLonLat(coord, 'BN') : " +
printArray(ol.proj.fromLonLat(coord, 'BN'), " "));
// http://openlayers.org/en/master/examples/reprojection-image.html
proj4.defs('EPSG:29873', "+proj=omerc +lat_0=4 +lonc=115 +alpha=53.31582047222222 "+
"+k=0.99984 +x_0=590476.87 +y_0=442857.65 " +
"+ellps=evrstSS +units=m +no_defs");
console.log("ol.proj.transform(coord, 'EPSG:4326', 'EPSG:29873') : " +
printArray(ol.proj.transform(coord, 'EPSG:4326', 'EPSG:29873'), " "));
console.log("ol.proj.fromLonLat(coord, 'EPSG:29873') : " +
printArray(ol.proj.fromLonLat(coord, 'EPSG:29873'), " "));
function printArray(arr, space1){ return arr[0] + space1 + ", " + arr[1]; }
Input Coordinates : 114.71360430047 , 4.6084126066456
Output Coordinates : 558706.105088 , 510127.869649
---------------------------------------------------------------------------------------------
ol.proj.fromLonLat(coord, 'BN') : 558706.0937005071 , 510098.552281862
ol.proj.transform( coord, 'EPSG:4326','EPSG:29873') : 558706.0937005071 , 510098.552281862
ol.proj.fromLonLat(coord, 'EPSG:29873') : 558706.0937005071 , 510098.552281862
Output
NOPE!
Though most likely me?
Back to the Drawing Board
Curl it up
Mukims
Kampongs
Buses!!!!!
Route Signboard
GeoJSON in Github
Tools!
- Mapping Libraries
- https://developers.google.com/maps/documentation/: the 'default'?
- http://leafletjs.com/: mobile friendly
- http://openlayers.org/: complex but powerful
- http://www.openstreetmap.org/
- GUI
Google My Maps
- Points, Lines, Polygons, Layers
- Sharing
- Driving routes (auto lay out lines)
- Photos on markers
- So hard to find it exists
GeoJSON.io
- Points, Lines, Polygons
- Custom data/attributes
- Layers somehow
- Techie
- No direct collaboration
- Github Integration is nice
MapBox
- Points, Lines, Polygons, Layers
- No sharing / Photos
- Modern looking
- Errors everywhere...
Mappit
- Points, Lines, Polygons, Photos
- No layers?
- Collaborative
- Clunky
CartoDB
- Points, Lines, Polygons
- Focus on data and visualisations (clustering)
- Not Collaborative?
Any to share?
Mapping Brunei
By Timothy Lim
Mapping Brunei
- 2,118