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I am trying to show in leaflet a geotiff raster image that was generated in gvSig. The basemap I am using in leaflet is a wms server with projection EPSG:3857.

Leaflet needs to know the upper right and bottom left corners in latitude and longitude coordinates which I get from the tfw file.

When I add my raster image the south west and north east corners are displayed in the correct position (the ones I specify to leaflet), but the other two are not. And most of the image is not displayed at the correct position either. It seems there is a problem with the projections.

gdalinfo of the raster file shows:

Driver: GTiff/GeoTIFF
Files: ModCombustible.tif
Size is 600, 945
Coordinate System is:
PROJCS["ETRS89 / UTM zone 30N",
    GEOGCS["ETRS89",
        DATUM["European_Terrestrial_Reference_System_1989",
            SPHEROID["GRS 1980",6378137,298.257222101,
                AUTHORITY["EPSG","7019"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6258"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4258"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",-3],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AXIS["Easting",EAST],
    AXIS["Northing",NORTH],
    AUTHORITY["EPSG","25830"]]
Origin = (713179.879402380902320,4381253.375599999912083)
Pixel Size = (5.001750158730428,-5.001750158730441)

I tried to use gdalwarp to reproject the raster in EPSG:3857 with the command: gdalwarp -t_srs EPSG:3857 ModCombustible.tif ModCombustible_3857.tif

but in the tfw file I am getting negative UTM easting coordinates which doesn't make any sense to me.

What should I do to properly show the raster image in leaflet?

EDIT: The negative easting coordinates are correct for the EPSG:3857 if they are west of London. Using the link provided by the user30184 I could translate the coordinates to latitude and longitude and show the image at the correct position.

EDIT2: To clarify basic concepts which were not clear to me: as IvanSanchez mentioned in the comments, UTM (Universal Transverse Mercator) is a system of 60 different projections using false easting and northing. In the other hand Web Mercator (EPSG:3857) is not UTM but uses easting and northing coordinates to define a position. It is the de facto standard for web map applications.

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    If you are west to London then EPSG:3857 eastings are negative epsg.io/… – user30184 Feb 9 '17 at 15:24
  • Thank you! I did not realize that EPSG:3857 can be negative. In the link you provided I could transform to lat long and load the raster in leaflet at the correct position :) – Guillermo Feb 10 '17 at 19:02
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Just to be sure, use the -s_srs option of gdalwarp to force a source SRS for the warping, e.g.:

gdalwarp -s_srs EPSG:25830 -t_srs EPSG:3857 ModCombustible.tif ModCombustible_3857.tif
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  • Thank you. I added the source SRS but I keep getting negative utm coordinates Upper Left ( -57917.696, 4801412.920) ( 0d31'13.02"W, 39d33'16.20"N) Lower Left ( -57917.696, 4795165.270) ( 0d31'13.02"W, 39d30'40.37"N) Upper Right ( -53865.167, 4801412.920) ( 0d29' 1.96"W, 39d33'16.20"N) Lower Right ( -53865.167, 4795165.270) ( 0d29' 1.96"W, 39d30'40.37"N) Center ( -55891.431, 4798289.095) ( 0d30' 7.49"W, 39d31'58.29"N) – Guillermo Feb 10 '17 at 18:42
  • Don't call the UTM coordinates, they are EPSG:3857 (Web Mercator) coordinates, and propably just right. – user30184 Feb 10 '17 at 19:39
  • I am a bit confused with the vocabulary, I thought that UTM was an umbrella term for any Easting Northing projection. But I guess it is a map projection itself and each UTM zone has its own EPSG code. Is that correct? In that case I will edit the question to clarify it. – Guillermo Feb 13 '17 at 10:37
  • No, UTM stands for Universal Transverse Mercator. It has a false easting and false northing, but other projections (such as polar stereographic) also do. UTM is not a projection; UTM is a system of 60 different but obviously similar projections and CRSs. – IvanSanchez Feb 13 '17 at 14:06

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