[FWTools] NULL or background values during merges/warp

Frank Warmerdam warmerdam at pobox.com
Mon Jan 22 00:27:59 EST 2007

Shaun Kolomeitz wrote:
> Dear FWTools,
> I am wondering if there is a way to specify a NULL value when merging
> images which have those annoying black strips on their edges ?
> In the past I have clipped images to remove this "strip", but when you
> are processing 500+ images this gets way too time intensive.
> Ideally I'd like the merge process to ignore band values of 0,0,0
> (especially around the edge). I realise this is probably going to
> exclude some pixels which are actually "black" as opposed to being
> "NULL", but I can't see any other way around it.
> I can demonstrate this more graphically if required.


The gdalwarp command has the -srcnodata switch which should do that.

gdal_merge.py has a roughly corresponding -n switch.

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

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