[Gdal-dev] GDAL_warp output image sizes vary.... Why?

[Frank Warmerdam]

Sampson, David wrote:
> Hey folks
> 
> I am batching the georef of a bunch of images and find GREAT variances 
> between input and output file sizes….
> 
> As the input file size is pretty consistent, and the same X,Y points are 
> used for GCP's in each image and the outsize option is set for 67%  I 
> would expect a consisent drop in file sizes.
> 
> Why is this not the case? Why do the gdal_warp images maintain their 
> appropriate file sizes?  And how can I add this condition in?
> 
> Note. Images start off as 32 bit and end off at 16bit (there is a 50% 
> drop already).
> 
> I have had cases where the output file is as large as 50 MEGS….
> 
> Why would the output file be larger than the intermediate file?
> 
> Anyone explain this?

Dave,

Can you use the FWTools Shell "tiffinfo" on one of the input files, and one
of the output files?  I suspect the input files are compressed though there
are a few other possible factors.

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    | President OSGeo, http://osgeo.org