ImageTilesPlugin: Make "planar" display consistent, queryable #1353
Description
Currently there are two methods for displaying image tilesets: "ellipsoid" and "planar". The "ellipsoid" case works well and is easily queryable via lat / lon. However the "planar" case is not and is formatted in a way that makes its display unreliable:
- If using an equirect-style tiled image then the tiles are loaded with a width of 2 instead of 1 (as it does with web-mercator tile sets).
- Converting a latitude / longitude value to a world coordinate on the plane is not possibly currently. This is in part due to a lack of exposed API, inconsistent world scale of the tile set, and differing map projections.
- Multiple overlays are not possible with planar display since they rely on deriving the lat / lon from world coordinates.
Some possible solutions:
- Normalize all "planar" data to be in the range [0, 1]. The user can then scale the image based on the aspect ratio.
- Expose functions for converting lat / lon to local planar [0, 1] coordinates.
- Somehow keep the lat / lon coordinates present so the overlay plugin can use them? This may get complicated?
- Automatically convert between projections for consistent world locations on a planar map, which may also become complicated.