reprojecting geotiffs to spherical mercator using gdalwarp

Question

I would like to reproject raster images (tiffs+proj+tfw) files too "google's" projection using gdalwarp. From what I understand, google uses epsg:900913/epsg:3785. What I don't know is how to correctly state the source projection. I believe that UTM32N=epsg:32632. If I reproject using gdalwarp -s_srs epsg:32632 -t_srs:epsg:900913, would that be correct? If I open that file in global mapper, how do I adjust project and worldfile then?

This is the content of my .proj file:

PROJCS["AUT-UTM32N",
GEOGCS["GCS_WGS_1984",
DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["false_easting",500000.0],
PARAMETER["false_northing",0.0],
PARAMETER["central_meridian",9.0],
PARAMETER["scale_factor",0.9996],
PARAMETER["latitude_of_origin",0.0],

This is the .tfw file: 2.5000000000
0.0000000000
0.0000000000
-2.5000000000
550001.2500000000
5199998.7500000000
UNIT["Meter",1.0]]

Answer 1

The source projection should be read from the file, so you shouldn't have to state it. Try "gdalinfo" on the source file, and if it returns the proper projection, you are all set!

Answer 2

As Jason Birch pointed out in a recent answer to a similar post, if you want new .tfw files, you can specify a creation option to build new world files. -co "TFW=YES"

If you don't specify this, the output will be a geoTiff and you won't need (or want) the old world files because they will be in the old spatial reference system.

Answer 3

It doesn't look like your proj file is incomplete (or something was lost in pasting). In general if you want to workout an epsg code from a proj file you can go to http://prj2epsg.org/search and either upload the file or paste in the codes.

After some poking around it looks like your input projection might be epsg:32632 http://prj2epsg.org/epsg/32632