[Gdal-dev] scale factor in gdalwarp

Frank Warmerdam warmerdam at pobox.com
Wed Aug 20 11:53:57 EDT 2003

Jeff Jacober wrote:
> Hi.
> Im using GDAL to reproject a Spot Quicklook and I seem to be having a bit 
> of trouble with one of my projection parameters.
> I am using:
> gdalwarp -t_srs "+proj=tmerc +datum=NAD83 +lon_0=-115 +lat_0=0 
> +k_0=0.9992 +x_0=500000 +y_0=0" -tr 120 120 quicklook.vrt out.tif
> The target projection is a custom projection common to Alberta(Canada) 
> that we refer to as '10TM'.
> The trouble I am having is that my scale factor (which I believe I am 
> correct in saying is k_0) doesnt seem to affect the output.  I have tried 
> using +k_0=0.8, +k_0=1.8 and +k_0=2.2 and my output file is always the 
> same and always has a scale factor of 1.


Try +k instead of +k_0.  While I believe +k_0 is a valid parameter for
some projections, it does not appear to be the normal way of indicating scale
factor for TM.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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