RFC 140 Errata

[jng]

According to the original RFC 140, I wrote the following about the XYZ tile provider

The "XYZ" provider implements tile rendering and access using the XYZ tiling scheme. Coordinate System is always LL84 ...

In further tests, this is proved to be incorrect. The actual Cooordinate System should actually always be WGS84.PseudoMercator

Having a LL84 coordinate system for XYZ tile sets produces tiles with noticeable visual distortion, whereas tiles from XYZ tile sets with a WGS84.PseudoMercator coordinate system have more crisp visual fidelity.

Attached is:

• A visual comparison of two different XYZ tile sets in both LL84 and WGS84.PseudoMercator coordinate systems
• A patch to set the correct coordinate system to WGS84.PseudoMercator instead of LL84

From a client tooling perspective, tile sets should be working against the WGS84.PseudoMercator coordinate system instead of LL84 in terms of tile set extents being set and/or transformed.

[jng]

Fixed r8581