2D Open Street Map Data Representation in Meters

Question

I am in the process of converting OSM data into an open source Minecraft port (written in javascript - voxel.js). The javascript rendition is written such that each voxel (arbitrarily defined as a cubic meter) is created as a relation from a single point of origin (x,y,z)(0,0,0).

As an example, if one wanted to create a cubic chunk of voxels, one would simply generate voxels as a relation to the origin (0,0,0) : [(0,0,0),(1,0,0), (0,1,0)...].

My question is this: I've exported OSM data, and the standard XML output (.osm) plots nodes in latitude and longitude. My initial thought is that I can create a map by calculating the distance of each node from an arbitrary point of origin (0,0,0) = (37.77559, -122.41392) using the Haversine formula, convert the distance to meters, find the bearing, and plot it as a relation to (0,0,0).

I've noticed, however, that there are a number of other export formats available: (.osm.pbf, .osm2pgsql, .imposm). I'm assuming they plot nodes in a similar fashion (lat, lng), but some of them have the ability to import directly into a database (e.g. PostgreSQL).

I've heard of people using PG add-ons like PostGIS, but (as this is my first dive into GIS) I'm unfamiliar with their capabilities and whether something like PostGIS would help me in plotting OSM data into a 2D voxel grid.

Are there functions within add-ons like PostGIS that would enable me to dynamically calculate the distance between two Lat/Lng points, and plot them in an x,y fashion?

I guess, fundamentally, my question is: if I create a script that plots OSM data into an x,y grid would I be reinventing the wheel, or is there a more efficient way to do this?

Mirco Mirco · Accepted Answer · 2013-02-11T14:57:51

You need to transform from the spherical coordinates (LatLon, using WGS84) to cartesian coordinates, like googles spherical mercator.

In pseudo code

    transform(double lat, double lon) {

double wgs84radius = 6378137;
double shift = PI * wgs84radius;
double x = lon * shift / 180;
double y = log(tan((90+lat)*PI/360)/ (PI/180);
return {x,y}
}

This is the simplest way. Keep in mind that Lat/Lon are angles, while x and y are distances from (0/0)

2D Open Street Map Data Representation in Meters

2 Answers