[gdal-dev] problems with calculations with very small numbers (nearzero)

[G. Allegri]

Ops, you're right Bob. So the problem is the huge negative value... So the
problem is how to substitute it, maybe with a more treatable value outside
my raster range...

giovanni



2011/10/31 Moskovitz, Bob <Bob.Moskovitz at conservation.ca.gov>

> Hi Giovanni,****
>
> ** **
>
> I’ve seen -3.4028234663852886e+038 (which is a huge negative value.  Your
> minds eye probably saw a “-“ instead of “+”)  as a nodata value.****
>
> ** **
>
> Regards,****
>
> Bob****
>
> ** **
>
> Bob Moskovitz****
>
> Seismic Hazards Mapping Program****
>
> California Geological Survey****
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> *From:* gdal-dev-bounces at lists.osgeo.org [mailto:
> gdal-dev-bounces at lists.osgeo.org] *On Behalf Of *G. Allegri
> *Sent:* Monday, October 31, 2011 11:19 AM
> *To:* gdal-dev at lists.osgeo.org
> *Subject:* [gdal-dev] problems with calculations with very small numbers
> (nearzero)****
>
> ** **
>
> Hi, ****
>
> I'm having some troubles with raster algebra on a raster with very small
> (near zero, but not).****
>
> I'm using numpy (through python gdal) to do a multiplication, eg
> numpy.multiply(rasterarr,2), but I obtain the following raster stats:
> http://pastebin.com/hHiUrWwD.****
>
> ** **
>
> I suppose that -3.4028234663852886e+038 values are causing the problems,
> and I wonder wha'ts the best way to deal with these kind of values... Maybe
> rounding them to zeros?****
>
> I've tried to do it using the LUT tag inside a VRT dataset, but it doesn't
> seem to do the job.****
>
> ** **
>
> giovanni****
>
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