[Gdal-dev] gdal_translate Basic Usage / UTM to latlong

[John R.]

Tim Osborn wrote:
> You indicate that the provider says the image is projected in UTM NAD83. 
> EPSG:2860 that you specified is a State Plane Coordinate System projection
> for the Central Zone of Wisconsin. 

Yes...I tried pretty much everything with "Wisconsin" in the name.

> 
> However, the coordinates output by gdalinfo don't look like UTM
> coordinates....they look more like State Plane Coordinates in meters. 

Interesting...is there a way I can confirm this?

> However, the lat long coordinates you say you expect for the center of the
> map would be located in the Wisconsin South State Plane Coordinate Zone.  So
> I would try EPSG:32154 which is NAD83 Wisconsin South Zone SPC, meter.

You are correct...it is South.

With "-a_srs EPSG:32154":

Center      (  661423.106,  351235.369) ( 89d13'8.87"W, 45d 9'30.70"N)

Should be approx:

  West 87d, 59.477 Minutes;  North 43d, 48.340 Minutes;

gdal_translate -a_srs overrides the projection for the output file. 
There doesn't seem to be an option for defining what is on the input 
side.  Is this because UTM is assumed assumed with gdal_translate?  Your 
comment that the coordinates look more like State Plane Coordinates in 
meters and that EPSG:32154 should be used as -a_srs implies that the 
-s_srs defines both the input side and output.

In an email response to by mail, someone else indicated the gdalwarp may 
be more appropriate as both s_srs and the t_srs (source and destination) 
coordinate systems can be overridden.  My attempts and making that work 
were tragic.  Is this a direction I should continue to pursue?

Thanks,

John