###export bounding box for reuse export LON1=-74.259094 export LAT1=40.477398 export LON2=-73.700165 export LAT2=40.91758
###mapbbox.js outputs a .png image using the Web Mercator (EPSG: 3857) projection
./mapbbox.js -h 480 -w 640 \ #dimensions of output image (px)
-b $LON1,$LAT1,$LON2,$LAT2 \ #bounds: lon1,lat1,lon2,lat2
-o NYC.png
gdal_translate georeferences the .png image by creating a GeoTIFF
gdal_translate -of Gtiff -co tfw=yes \ #output geotif file along with tfw (world file)
-a_ullr $LON1 $LAT2 $LON2 $LAT1 \ #bounds: upper left, lower right
-a_srs EPSG:3857 \ #source projection
NYC.png NYC.3857.tif #src dst
##gdalwarp reprojects the georeferenced tiff to World Equidistant Cylindrical (EPSG: 32663*)
gdalwarp -t_srs EPSG:32663 \ #target projection
NYC.3857.tif NYC.32663.tif #src dst
These two images are not identical. Overlaying the source image with the destination demonstrates that the image was reprojected.
######*see also http://spatialreference.org/ref/epsg/wgs-84-plate-carree/ notes:
| EPSG | Common Name(s) | Description |
|---|---|---|
| 4326 | Plate Carre (Geographic) | NOT yet transformed to a projection. Uses a coordinate system the same as a GLOBE (curved surface). |
| 3857 | Web Mercator | Uses a coordinate system the same as a MAP (flat surface). |
| 900913 | Web Mercator | Identical to EPSG 3857. Deprecated. |
Leaflet.js wants non-projected (EPSG 4326) GeoJSON. Leaflet does the projection to Web Mercator for you.
Web mercator NOT == spherical mercator google mercator == Web Mercator (Auxiliary Sphere)
Loading data to Mapbox Studio/TileMill has to be in WGS 84, Mercator EPSG:4326 Once those data gets uploaded, it converts into EPSG:3857 WebMercator