I have a set of PNG images downloaded from a service like:
http://tile.openstreetmap.org/{z}/{x}/{y}.png
The images are named:
09_118_180.PNG
09_119_180.PNG
etc.
How can I combine these image in FME and project them correctly?
Solved
How to set reference system for {x},{y},{z} PNG raster images
Best answer by jdh
OSM uses a slippy map.
To go from tile numbers to lat long use the following equations:
n = 2 ^ zoom lon_deg = xtile / n * 360.0 - 180.0
lat_rad = arctan(sinh(π * (1 - 2 * ytile / n)))
lat_deg = lat_rad * 180.0 / πThis returns the NW corner of the image. You can use xtile+0.5 and ytile+0.5 to get the center of the tile
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+37- Contributor
- 2002 replies
- Best Answer
OSM uses a slippy map.
To go from tile numbers to lat long use the following equations:
n = 2 ^ zoom lon_deg = xtile / n * 360.0 - 180.0
lat_rad = arctan(sinh(π * (1 - 2 * ytile / n)))
lat_deg = lat_rad * 180.0 / πThis returns the NW corner of the image. You can use xtile+0.5 and ytile+0.5 to get the center of the tile
+37- Contributor
- 2002 replies
OSM uses a slippy map.
To go from tile numbers to lat long use the following equations:
n = 2 ^ zoom lon_deg = xtile / n * 360.0 - 180.0
lat_rad = arctan(sinh(π * (1 - 2 * ytile / n)))
lat_deg = lat_rad * 180.0 / πThis returns the NW corner of the image. You can use xtile+0.5 and ytile+0.5 to get the center of the tile
Personally I would calculate all four corners and use the RasterGeoreferencer and then the RasterMosaicker, then use a CoordinateSystemSetter to define the projection as EPSG 3857.
OSM uses a slippy map.
To go from tile numbers to lat long use the following equations:
n = 2 ^ zoom lon_deg = xtile / n * 360.0 - 180.0
lat_rad = arctan(sinh(π * (1 - 2 * ytile / n)))
lat_deg = lat_rad * 180.0 / πThis returns the NW corner of the image. You can use xtile+0.5 and ytile+0.5 to get the center of the tile
Works like a charm, thank you!
I ended up not using the RasterMosaicker as it opened too many files which would require to use the Mosaicker in two steps. Instead I vectorized each raster individually and combined the results at the end, which probably also is faster for my scenario.
