I have added a online tile source in the 'XYZ Tiles' option, and added it as a layer, which works fine. But im trying to understand where the extents shown in the layer properties is coming from? When I just loaded a simple JPEG as a raster background, my coord system and extents was just the pixels of the background, and origin 0,0 in a corner. But now with the tile source the origin is the middle (which is not a big deal) but the extents are like (big, see image) it would seem totally disconnected from the actual image widths, which is throwing out my coord system.
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1 Answer
The coordinates for the zxy tile system are based off of the Web Mercator Projection: 3857. More information on the coordinate system is here:
You bounds are covering the whole world, and the width and height are the size of the world, when approximating a sphere.
40075016 meters is basically the circumference of the earth at the equator: https://en.wikipedia.org/wiki/Earth%27s_circumference
0,0 in the coordinate system is where the prime meridian meets the equator. Sometimes referred to as Null Island: https://en.wikipedia.org/wiki/Null_Island
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Ah ok, makes sense, thanks, is there some way to change this ? Im making a flat fictional game map, so not spherical, and would prefer it say 0-256 for example. Commented Jul 10, 2019 at 23:50