OSM data slightly distorted (flat projection)

Question

I've imported some OSM data into a 3D application, but the coordinates seem to be slightly distorted in the longitude axis compared to the map rendering on the OSM website.

OSM Screenshot 3D App Screenshot

I've "translated" the Latitude and Longitude values into X/Z coordinates as is. Is there some special value that I need to multiply with the longitude value to get rid of the stretch?

scai · Accepted Answer · 2014-09-02 06:37:58Z

4

You didn't mention how you "translated" lat/lon into x/y but I guess you are just using a different projection.

Raw OSM data is projected in EPSG:4326 aka WGS84. OSM's slippy map uses EPSG:3857 aka Web Mercator projection. The slippy map tilenames wiki page provides some additional information.

answered Sep 2, 2014 at 6:37

scai

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Niklas R Over a year ago

Thanks for your answer. From what I gathered and with a little trial&error I figured dividing the longitude by PI / 2 yields pretty accurate results.

darkfrei · Accepted Answer · 2025-02-20 18:00:09Z

0

Thanks to scai!

The code to make Mercator projection from OpenStreetMaps:

local function mercatorY(lat)
    local radLat = math.rad(lat)
    return math.deg(math.log (math.tan(radLat) + 1/math.cos(radLat)))
end

Map: https://osm.org/go/0JAeZ7oTQ

answered Feb 20 at 18:00

darkfrei

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